paulson@12196
|
1 |
(* Title : Transcendental.thy
|
paulson@12196
|
2 |
Author : Jacques D. Fleuriot
|
paulson@12196
|
3 |
Copyright : 1998,1999 University of Cambridge
|
paulson@13958
|
4 |
1999,2001 University of Edinburgh
|
paulson@15077
|
5 |
Conversion to Isar and new proofs by Lawrence C Paulson, 2004
|
paulson@12196
|
6 |
*)
|
paulson@12196
|
7 |
|
paulson@15077
|
8 |
header{*Power Series, Transcendental Functions etc.*}
|
paulson@15077
|
9 |
|
nipkow@15131
|
10 |
theory Transcendental
|
haftmann@25600
|
11 |
imports Fact Series Deriv NthRoot
|
nipkow@15131
|
12 |
begin
|
paulson@15077
|
13 |
|
huffman@29164
|
14 |
subsection {* Properties of Power Series *}
|
paulson@15077
|
15 |
|
huffman@23082
|
16 |
lemma lemma_realpow_diff:
|
haftmann@31017
|
17 |
fixes y :: "'a::monoid_mult"
|
huffman@23082
|
18 |
shows "p \<le> n \<Longrightarrow> y ^ (Suc n - p) = (y ^ (n - p)) * y"
|
huffman@23082
|
19 |
proof -
|
huffman@23082
|
20 |
assume "p \<le> n"
|
huffman@23082
|
21 |
hence "Suc n - p = Suc (n - p)" by (rule Suc_diff_le)
|
huffman@30269
|
22 |
thus ?thesis by (simp add: power_commutes)
|
huffman@23082
|
23 |
qed
|
paulson@15077
|
24 |
|
paulson@15077
|
25 |
lemma lemma_realpow_diff_sumr:
|
haftmann@31017
|
26 |
fixes y :: "'a::{comm_semiring_0,monoid_mult}" shows
|
huffman@23082
|
27 |
"(\<Sum>p=0..<Suc n. (x ^ p) * y ^ (Suc n - p)) =
|
huffman@23082
|
28 |
y * (\<Sum>p=0..<Suc n. (x ^ p) * y ^ (n - p))"
|
huffman@29163
|
29 |
by (simp add: setsum_right_distrib lemma_realpow_diff mult_ac
|
huffman@29163
|
30 |
del: setsum_op_ivl_Suc cong: strong_setsum_cong)
|
paulson@15077
|
31 |
|
paulson@15229
|
32 |
lemma lemma_realpow_diff_sumr2:
|
haftmann@31017
|
33 |
fixes y :: "'a::{comm_ring,monoid_mult}" shows
|
paulson@15229
|
34 |
"x ^ (Suc n) - y ^ (Suc n) =
|
huffman@23082
|
35 |
(x - y) * (\<Sum>p=0..<Suc n. (x ^ p) * y ^ (n - p))"
|
huffman@30269
|
36 |
apply (induct n, simp)
|
huffman@30269
|
37 |
apply (simp del: setsum_op_ivl_Suc)
|
nipkow@15561
|
38 |
apply (subst setsum_op_ivl_Suc)
|
huffman@23082
|
39 |
apply (subst lemma_realpow_diff_sumr)
|
huffman@23082
|
40 |
apply (simp add: right_distrib del: setsum_op_ivl_Suc)
|
huffman@23082
|
41 |
apply (subst mult_left_commute [where a="x - y"])
|
huffman@23082
|
42 |
apply (erule subst)
|
huffman@30269
|
43 |
apply (simp add: algebra_simps)
|
paulson@15077
|
44 |
done
|
paulson@15077
|
45 |
|
paulson@15229
|
46 |
lemma lemma_realpow_rev_sumr:
|
nipkow@15539
|
47 |
"(\<Sum>p=0..<Suc n. (x ^ p) * (y ^ (n - p))) =
|
huffman@23082
|
48 |
(\<Sum>p=0..<Suc n. (x ^ (n - p)) * (y ^ p))"
|
huffman@23082
|
49 |
apply (rule setsum_reindex_cong [where f="\<lambda>i. n - i"])
|
huffman@23082
|
50 |
apply (rule inj_onI, simp)
|
huffman@23082
|
51 |
apply auto
|
huffman@23082
|
52 |
apply (rule_tac x="n - x" in image_eqI, simp, simp)
|
paulson@15077
|
53 |
done
|
paulson@15077
|
54 |
|
paulson@15077
|
55 |
text{*Power series has a `circle` of convergence, i.e. if it sums for @{term
|
paulson@15077
|
56 |
x}, then it sums absolutely for @{term z} with @{term "\<bar>z\<bar> < \<bar>x\<bar>"}.*}
|
paulson@15077
|
57 |
|
paulson@15077
|
58 |
lemma powser_insidea:
|
haftmann@31017
|
59 |
fixes x z :: "'a::{real_normed_field,banach}"
|
huffman@20849
|
60 |
assumes 1: "summable (\<lambda>n. f n * x ^ n)"
|
huffman@23082
|
61 |
assumes 2: "norm z < norm x"
|
huffman@23082
|
62 |
shows "summable (\<lambda>n. norm (f n * z ^ n))"
|
huffman@20849
|
63 |
proof -
|
huffman@20849
|
64 |
from 2 have x_neq_0: "x \<noteq> 0" by clarsimp
|
huffman@20849
|
65 |
from 1 have "(\<lambda>n. f n * x ^ n) ----> 0"
|
huffman@20849
|
66 |
by (rule summable_LIMSEQ_zero)
|
huffman@20849
|
67 |
hence "convergent (\<lambda>n. f n * x ^ n)"
|
huffman@20849
|
68 |
by (rule convergentI)
|
huffman@20849
|
69 |
hence "Cauchy (\<lambda>n. f n * x ^ n)"
|
huffman@20849
|
70 |
by (simp add: Cauchy_convergent_iff)
|
huffman@20849
|
71 |
hence "Bseq (\<lambda>n. f n * x ^ n)"
|
huffman@20849
|
72 |
by (rule Cauchy_Bseq)
|
huffman@23082
|
73 |
then obtain K where 3: "0 < K" and 4: "\<forall>n. norm (f n * x ^ n) \<le> K"
|
huffman@20849
|
74 |
by (simp add: Bseq_def, safe)
|
huffman@23082
|
75 |
have "\<exists>N. \<forall>n\<ge>N. norm (norm (f n * z ^ n)) \<le>
|
huffman@23082
|
76 |
K * norm (z ^ n) * inverse (norm (x ^ n))"
|
huffman@20849
|
77 |
proof (intro exI allI impI)
|
huffman@20849
|
78 |
fix n::nat assume "0 \<le> n"
|
huffman@23082
|
79 |
have "norm (norm (f n * z ^ n)) * norm (x ^ n) =
|
huffman@23082
|
80 |
norm (f n * x ^ n) * norm (z ^ n)"
|
huffman@23082
|
81 |
by (simp add: norm_mult abs_mult)
|
huffman@23082
|
82 |
also have "\<dots> \<le> K * norm (z ^ n)"
|
huffman@23082
|
83 |
by (simp only: mult_right_mono 4 norm_ge_zero)
|
huffman@23082
|
84 |
also have "\<dots> = K * norm (z ^ n) * (inverse (norm (x ^ n)) * norm (x ^ n))"
|
huffman@20849
|
85 |
by (simp add: x_neq_0)
|
huffman@23082
|
86 |
also have "\<dots> = K * norm (z ^ n) * inverse (norm (x ^ n)) * norm (x ^ n)"
|
huffman@20849
|
87 |
by (simp only: mult_assoc)
|
huffman@23082
|
88 |
finally show "norm (norm (f n * z ^ n)) \<le>
|
huffman@23082
|
89 |
K * norm (z ^ n) * inverse (norm (x ^ n))"
|
huffman@20849
|
90 |
by (simp add: mult_le_cancel_right x_neq_0)
|
huffman@20849
|
91 |
qed
|
huffman@23082
|
92 |
moreover have "summable (\<lambda>n. K * norm (z ^ n) * inverse (norm (x ^ n)))"
|
huffman@20849
|
93 |
proof -
|
huffman@23082
|
94 |
from 2 have "norm (norm (z * inverse x)) < 1"
|
huffman@23082
|
95 |
using x_neq_0
|
huffman@23082
|
96 |
by (simp add: nonzero_norm_divide divide_inverse [symmetric])
|
huffman@23082
|
97 |
hence "summable (\<lambda>n. norm (z * inverse x) ^ n)"
|
huffman@20849
|
98 |
by (rule summable_geometric)
|
huffman@23082
|
99 |
hence "summable (\<lambda>n. K * norm (z * inverse x) ^ n)"
|
huffman@20849
|
100 |
by (rule summable_mult)
|
huffman@23082
|
101 |
thus "summable (\<lambda>n. K * norm (z ^ n) * inverse (norm (x ^ n)))"
|
huffman@23082
|
102 |
using x_neq_0
|
huffman@23082
|
103 |
by (simp add: norm_mult nonzero_norm_inverse power_mult_distrib
|
huffman@23082
|
104 |
power_inverse norm_power mult_assoc)
|
huffman@20849
|
105 |
qed
|
huffman@23082
|
106 |
ultimately show "summable (\<lambda>n. norm (f n * z ^ n))"
|
huffman@20849
|
107 |
by (rule summable_comparison_test)
|
huffman@20849
|
108 |
qed
|
paulson@15077
|
109 |
|
paulson@15229
|
110 |
lemma powser_inside:
|
haftmann@31017
|
111 |
fixes f :: "nat \<Rightarrow> 'a::{real_normed_field,banach}" shows
|
huffman@23082
|
112 |
"[| summable (%n. f(n) * (x ^ n)); norm z < norm x |]
|
paulson@15077
|
113 |
==> summable (%n. f(n) * (z ^ n))"
|
huffman@23082
|
114 |
by (rule powser_insidea [THEN summable_norm_cancel])
|
paulson@15077
|
115 |
|
hoelzl@29740
|
116 |
lemma sum_split_even_odd: fixes f :: "nat \<Rightarrow> real" shows
|
hoelzl@29740
|
117 |
"(\<Sum> i = 0 ..< 2 * n. if even i then f i else g i) =
|
hoelzl@29740
|
118 |
(\<Sum> i = 0 ..< n. f (2 * i)) + (\<Sum> i = 0 ..< n. g (2 * i + 1))"
|
hoelzl@29740
|
119 |
proof (induct n)
|
hoelzl@29740
|
120 |
case (Suc n)
|
hoelzl@29740
|
121 |
have "(\<Sum> i = 0 ..< 2 * Suc n. if even i then f i else g i) =
|
hoelzl@29740
|
122 |
(\<Sum> i = 0 ..< n. f (2 * i)) + (\<Sum> i = 0 ..< n. g (2 * i + 1)) + (f (2 * n) + g (2 * n + 1))"
|
huffman@30019
|
123 |
using Suc.hyps unfolding One_nat_def by auto
|
hoelzl@29740
|
124 |
also have "\<dots> = (\<Sum> i = 0 ..< Suc n. f (2 * i)) + (\<Sum> i = 0 ..< Suc n. g (2 * i + 1))" by auto
|
hoelzl@29740
|
125 |
finally show ?case .
|
hoelzl@29740
|
126 |
qed auto
|
hoelzl@29740
|
127 |
|
hoelzl@29740
|
128 |
lemma sums_if': fixes g :: "nat \<Rightarrow> real" assumes "g sums x"
|
hoelzl@29740
|
129 |
shows "(\<lambda> n. if even n then 0 else g ((n - 1) div 2)) sums x"
|
hoelzl@29740
|
130 |
unfolding sums_def
|
hoelzl@29740
|
131 |
proof (rule LIMSEQ_I)
|
hoelzl@29740
|
132 |
fix r :: real assume "0 < r"
|
hoelzl@29740
|
133 |
from `g sums x`[unfolded sums_def, THEN LIMSEQ_D, OF this]
|
hoelzl@29740
|
134 |
obtain no where no_eq: "\<And> n. n \<ge> no \<Longrightarrow> (norm (setsum g { 0..<n } - x) < r)" by blast
|
hoelzl@29740
|
135 |
|
hoelzl@29740
|
136 |
let ?SUM = "\<lambda> m. \<Sum> i = 0 ..< m. if even i then 0 else g ((i - 1) div 2)"
|
hoelzl@29740
|
137 |
{ fix m assume "m \<ge> 2 * no" hence "m div 2 \<ge> no" by auto
|
hoelzl@29740
|
138 |
have sum_eq: "?SUM (2 * (m div 2)) = setsum g { 0 ..< m div 2 }"
|
hoelzl@29740
|
139 |
using sum_split_even_odd by auto
|
hoelzl@29740
|
140 |
hence "(norm (?SUM (2 * (m div 2)) - x) < r)" using no_eq unfolding sum_eq using `m div 2 \<ge> no` by auto
|
hoelzl@29740
|
141 |
moreover
|
hoelzl@29740
|
142 |
have "?SUM (2 * (m div 2)) = ?SUM m"
|
hoelzl@29740
|
143 |
proof (cases "even m")
|
hoelzl@29740
|
144 |
case True show ?thesis unfolding even_nat_div_two_times_two[OF True, unfolded numeral_2_eq_2[symmetric]] ..
|
hoelzl@29740
|
145 |
next
|
hoelzl@29740
|
146 |
case False hence "even (Suc m)" by auto
|
hoelzl@29740
|
147 |
from even_nat_div_two_times_two[OF this, unfolded numeral_2_eq_2[symmetric]] odd_nat_plus_one_div_two[OF False, unfolded numeral_2_eq_2[symmetric]]
|
hoelzl@29740
|
148 |
have eq: "Suc (2 * (m div 2)) = m" by auto
|
hoelzl@29740
|
149 |
hence "even (2 * (m div 2))" using `odd m` by auto
|
hoelzl@29740
|
150 |
have "?SUM m = ?SUM (Suc (2 * (m div 2)))" unfolding eq ..
|
hoelzl@29740
|
151 |
also have "\<dots> = ?SUM (2 * (m div 2))" using `even (2 * (m div 2))` by auto
|
hoelzl@29740
|
152 |
finally show ?thesis by auto
|
hoelzl@29740
|
153 |
qed
|
hoelzl@29740
|
154 |
ultimately have "(norm (?SUM m - x) < r)" by auto
|
hoelzl@29740
|
155 |
}
|
hoelzl@29740
|
156 |
thus "\<exists> no. \<forall> m \<ge> no. norm (?SUM m - x) < r" by blast
|
hoelzl@29740
|
157 |
qed
|
hoelzl@29740
|
158 |
|
hoelzl@29740
|
159 |
lemma sums_if: fixes g :: "nat \<Rightarrow> real" assumes "g sums x" and "f sums y"
|
hoelzl@29740
|
160 |
shows "(\<lambda> n. if even n then f (n div 2) else g ((n - 1) div 2)) sums (x + y)"
|
hoelzl@29740
|
161 |
proof -
|
hoelzl@29740
|
162 |
let ?s = "\<lambda> n. if even n then 0 else f ((n - 1) div 2)"
|
hoelzl@29740
|
163 |
{ fix B T E have "(if B then (0 :: real) else E) + (if B then T else 0) = (if B then T else E)"
|
hoelzl@29740
|
164 |
by (cases B) auto } note if_sum = this
|
hoelzl@29740
|
165 |
have g_sums: "(\<lambda> n. if even n then 0 else g ((n - 1) div 2)) sums x" using sums_if'[OF `g sums x`] .
|
hoelzl@29740
|
166 |
{
|
hoelzl@29740
|
167 |
have "?s 0 = 0" by auto
|
hoelzl@29740
|
168 |
have Suc_m1: "\<And> n. Suc n - 1 = n" by auto
|
hoelzl@29740
|
169 |
{ fix B T E have "(if \<not> B then T else E) = (if B then E else T)" by auto } note if_eq = this
|
hoelzl@29740
|
170 |
|
hoelzl@29740
|
171 |
have "?s sums y" using sums_if'[OF `f sums y`] .
|
hoelzl@29740
|
172 |
from this[unfolded sums_def, THEN LIMSEQ_Suc]
|
hoelzl@29740
|
173 |
have "(\<lambda> n. if even n then f (n div 2) else 0) sums y"
|
hoelzl@29740
|
174 |
unfolding sums_def setsum_shift_lb_Suc0_0_upt[where f="?s", OF `?s 0 = 0`, symmetric]
|
hoelzl@29740
|
175 |
image_Suc_atLeastLessThan[symmetric] setsum_reindex[OF inj_Suc, unfolded comp_def]
|
nipkow@31148
|
176 |
even_Suc Suc_m1 if_eq .
|
hoelzl@29740
|
177 |
} from sums_add[OF g_sums this]
|
hoelzl@29740
|
178 |
show ?thesis unfolding if_sum .
|
hoelzl@29740
|
179 |
qed
|
hoelzl@29740
|
180 |
|
hoelzl@29740
|
181 |
subsection {* Alternating series test / Leibniz formula *}
|
hoelzl@29740
|
182 |
|
hoelzl@29740
|
183 |
lemma sums_alternating_upper_lower:
|
hoelzl@29740
|
184 |
fixes a :: "nat \<Rightarrow> real"
|
hoelzl@29740
|
185 |
assumes mono: "\<And>n. a (Suc n) \<le> a n" and a_pos: "\<And>n. 0 \<le> a n" and "a ----> 0"
|
hoelzl@29740
|
186 |
shows "\<exists>l. ((\<forall>n. (\<Sum>i=0..<2*n. -1^i*a i) \<le> l) \<and> (\<lambda> n. \<Sum>i=0..<2*n. -1^i*a i) ----> l) \<and>
|
hoelzl@29740
|
187 |
((\<forall>n. l \<le> (\<Sum>i=0..<2*n + 1. -1^i*a i)) \<and> (\<lambda> n. \<Sum>i=0..<2*n + 1. -1^i*a i) ----> l)"
|
hoelzl@29740
|
188 |
(is "\<exists>l. ((\<forall>n. ?f n \<le> l) \<and> _) \<and> ((\<forall>n. l \<le> ?g n) \<and> _)")
|
hoelzl@29740
|
189 |
proof -
|
huffman@30019
|
190 |
have fg_diff: "\<And>n. ?f n - ?g n = - a (2 * n)" unfolding One_nat_def by auto
|
hoelzl@29740
|
191 |
|
hoelzl@29740
|
192 |
have "\<forall> n. ?f n \<le> ?f (Suc n)"
|
hoelzl@29740
|
193 |
proof fix n show "?f n \<le> ?f (Suc n)" using mono[of "2*n"] by auto qed
|
hoelzl@29740
|
194 |
moreover
|
hoelzl@29740
|
195 |
have "\<forall> n. ?g (Suc n) \<le> ?g n"
|
huffman@30019
|
196 |
proof fix n show "?g (Suc n) \<le> ?g n" using mono[of "Suc (2*n)"]
|
huffman@30019
|
197 |
unfolding One_nat_def by auto qed
|
hoelzl@29740
|
198 |
moreover
|
hoelzl@29740
|
199 |
have "\<forall> n. ?f n \<le> ?g n"
|
huffman@30019
|
200 |
proof fix n show "?f n \<le> ?g n" using fg_diff a_pos
|
huffman@30019
|
201 |
unfolding One_nat_def by auto qed
|
hoelzl@29740
|
202 |
moreover
|
hoelzl@29740
|
203 |
have "(\<lambda> n. ?f n - ?g n) ----> 0" unfolding fg_diff
|
hoelzl@29740
|
204 |
proof (rule LIMSEQ_I)
|
hoelzl@29740
|
205 |
fix r :: real assume "0 < r"
|
hoelzl@29740
|
206 |
with `a ----> 0`[THEN LIMSEQ_D]
|
hoelzl@29740
|
207 |
obtain N where "\<And> n. n \<ge> N \<Longrightarrow> norm (a n - 0) < r" by auto
|
hoelzl@29740
|
208 |
hence "\<forall> n \<ge> N. norm (- a (2 * n) - 0) < r" by auto
|
hoelzl@29740
|
209 |
thus "\<exists> N. \<forall> n \<ge> N. norm (- a (2 * n) - 0) < r" by auto
|
hoelzl@29740
|
210 |
qed
|
hoelzl@29740
|
211 |
ultimately
|
hoelzl@29740
|
212 |
show ?thesis by (rule lemma_nest_unique)
|
hoelzl@29740
|
213 |
qed
|
hoelzl@29740
|
214 |
|
hoelzl@29740
|
215 |
lemma summable_Leibniz': fixes a :: "nat \<Rightarrow> real"
|
hoelzl@29740
|
216 |
assumes a_zero: "a ----> 0" and a_pos: "\<And> n. 0 \<le> a n"
|
hoelzl@29740
|
217 |
and a_monotone: "\<And> n. a (Suc n) \<le> a n"
|
hoelzl@29740
|
218 |
shows summable: "summable (\<lambda> n. (-1)^n * a n)"
|
hoelzl@29740
|
219 |
and "\<And>n. (\<Sum>i=0..<2*n. (-1)^i*a i) \<le> (\<Sum>i. (-1)^i*a i)"
|
hoelzl@29740
|
220 |
and "(\<lambda>n. \<Sum>i=0..<2*n. (-1)^i*a i) ----> (\<Sum>i. (-1)^i*a i)"
|
hoelzl@29740
|
221 |
and "\<And>n. (\<Sum>i. (-1)^i*a i) \<le> (\<Sum>i=0..<2*n+1. (-1)^i*a i)"
|
hoelzl@29740
|
222 |
and "(\<lambda>n. \<Sum>i=0..<2*n+1. (-1)^i*a i) ----> (\<Sum>i. (-1)^i*a i)"
|
hoelzl@29740
|
223 |
proof -
|
hoelzl@29740
|
224 |
let "?S n" = "(-1)^n * a n"
|
hoelzl@29740
|
225 |
let "?P n" = "\<Sum>i=0..<n. ?S i"
|
hoelzl@29740
|
226 |
let "?f n" = "?P (2 * n)"
|
hoelzl@29740
|
227 |
let "?g n" = "?P (2 * n + 1)"
|
hoelzl@29740
|
228 |
obtain l :: real where below_l: "\<forall> n. ?f n \<le> l" and "?f ----> l" and above_l: "\<forall> n. l \<le> ?g n" and "?g ----> l"
|
hoelzl@29740
|
229 |
using sums_alternating_upper_lower[OF a_monotone a_pos a_zero] by blast
|
hoelzl@29740
|
230 |
|
hoelzl@29740
|
231 |
let ?Sa = "\<lambda> m. \<Sum> n = 0..<m. ?S n"
|
hoelzl@29740
|
232 |
have "?Sa ----> l"
|
hoelzl@29740
|
233 |
proof (rule LIMSEQ_I)
|
hoelzl@29740
|
234 |
fix r :: real assume "0 < r"
|
hoelzl@29740
|
235 |
|
hoelzl@29740
|
236 |
with `?f ----> l`[THEN LIMSEQ_D]
|
hoelzl@29740
|
237 |
obtain f_no where f: "\<And> n. n \<ge> f_no \<Longrightarrow> norm (?f n - l) < r" by auto
|
hoelzl@29740
|
238 |
|
hoelzl@29740
|
239 |
from `0 < r` `?g ----> l`[THEN LIMSEQ_D]
|
hoelzl@29740
|
240 |
obtain g_no where g: "\<And> n. n \<ge> g_no \<Longrightarrow> norm (?g n - l) < r" by auto
|
hoelzl@29740
|
241 |
|
hoelzl@29740
|
242 |
{ fix n :: nat
|
hoelzl@29740
|
243 |
assume "n \<ge> (max (2 * f_no) (2 * g_no))" hence "n \<ge> 2 * f_no" and "n \<ge> 2 * g_no" by auto
|
hoelzl@29740
|
244 |
have "norm (?Sa n - l) < r"
|
hoelzl@29740
|
245 |
proof (cases "even n")
|
hoelzl@29740
|
246 |
case True from even_nat_div_two_times_two[OF this]
|
hoelzl@29740
|
247 |
have n_eq: "2 * (n div 2) = n" unfolding numeral_2_eq_2[symmetric] by auto
|
hoelzl@29740
|
248 |
with `n \<ge> 2 * f_no` have "n div 2 \<ge> f_no" by auto
|
hoelzl@29740
|
249 |
from f[OF this]
|
hoelzl@29740
|
250 |
show ?thesis unfolding n_eq atLeastLessThanSuc_atLeastAtMost .
|
hoelzl@29740
|
251 |
next
|
hoelzl@29740
|
252 |
case False hence "even (n - 1)" using even_num_iff odd_pos by auto
|
hoelzl@29740
|
253 |
from even_nat_div_two_times_two[OF this]
|
hoelzl@29740
|
254 |
have n_eq: "2 * ((n - 1) div 2) = n - 1" unfolding numeral_2_eq_2[symmetric] by auto
|
hoelzl@29740
|
255 |
hence range_eq: "n - 1 + 1 = n" using odd_pos[OF False] by auto
|
hoelzl@29740
|
256 |
|
hoelzl@29740
|
257 |
from n_eq `n \<ge> 2 * g_no` have "(n - 1) div 2 \<ge> g_no" by auto
|
hoelzl@29740
|
258 |
from g[OF this]
|
hoelzl@29740
|
259 |
show ?thesis unfolding n_eq atLeastLessThanSuc_atLeastAtMost range_eq .
|
hoelzl@29740
|
260 |
qed
|
hoelzl@29740
|
261 |
}
|
hoelzl@29740
|
262 |
thus "\<exists> no. \<forall> n \<ge> no. norm (?Sa n - l) < r" by blast
|
hoelzl@29740
|
263 |
qed
|
hoelzl@29740
|
264 |
hence sums_l: "(\<lambda>i. (-1)^i * a i) sums l" unfolding sums_def atLeastLessThanSuc_atLeastAtMost[symmetric] .
|
hoelzl@29740
|
265 |
thus "summable ?S" using summable_def by auto
|
hoelzl@29740
|
266 |
|
hoelzl@29740
|
267 |
have "l = suminf ?S" using sums_unique[OF sums_l] .
|
hoelzl@29740
|
268 |
|
hoelzl@29740
|
269 |
{ fix n show "suminf ?S \<le> ?g n" unfolding sums_unique[OF sums_l, symmetric] using above_l by auto }
|
hoelzl@29740
|
270 |
{ fix n show "?f n \<le> suminf ?S" unfolding sums_unique[OF sums_l, symmetric] using below_l by auto }
|
hoelzl@29740
|
271 |
show "?g ----> suminf ?S" using `?g ----> l` `l = suminf ?S` by auto
|
hoelzl@29740
|
272 |
show "?f ----> suminf ?S" using `?f ----> l` `l = suminf ?S` by auto
|
hoelzl@29740
|
273 |
qed
|
hoelzl@29740
|
274 |
|
hoelzl@29740
|
275 |
theorem summable_Leibniz: fixes a :: "nat \<Rightarrow> real"
|
hoelzl@29740
|
276 |
assumes a_zero: "a ----> 0" and "monoseq a"
|
hoelzl@29740
|
277 |
shows "summable (\<lambda> n. (-1)^n * a n)" (is "?summable")
|
hoelzl@29740
|
278 |
and "0 < a 0 \<longrightarrow> (\<forall>n. (\<Sum>i. -1^i*a i) \<in> { \<Sum>i=0..<2*n. -1^i * a i .. \<Sum>i=0..<2*n+1. -1^i * a i})" (is "?pos")
|
hoelzl@29740
|
279 |
and "a 0 < 0 \<longrightarrow> (\<forall>n. (\<Sum>i. -1^i*a i) \<in> { \<Sum>i=0..<2*n+1. -1^i * a i .. \<Sum>i=0..<2*n. -1^i * a i})" (is "?neg")
|
hoelzl@29740
|
280 |
and "(\<lambda>n. \<Sum>i=0..<2*n. -1^i*a i) ----> (\<Sum>i. -1^i*a i)" (is "?f")
|
hoelzl@29740
|
281 |
and "(\<lambda>n. \<Sum>i=0..<2*n+1. -1^i*a i) ----> (\<Sum>i. -1^i*a i)" (is "?g")
|
hoelzl@29740
|
282 |
proof -
|
hoelzl@29740
|
283 |
have "?summable \<and> ?pos \<and> ?neg \<and> ?f \<and> ?g"
|
hoelzl@29740
|
284 |
proof (cases "(\<forall> n. 0 \<le> a n) \<and> (\<forall>m. \<forall>n\<ge>m. a n \<le> a m)")
|
hoelzl@29740
|
285 |
case True
|
hoelzl@29740
|
286 |
hence ord: "\<And>n m. m \<le> n \<Longrightarrow> a n \<le> a m" and ge0: "\<And> n. 0 \<le> a n" by auto
|
hoelzl@29740
|
287 |
{ fix n have "a (Suc n) \<le> a n" using ord[where n="Suc n" and m=n] by auto }
|
hoelzl@29740
|
288 |
note leibniz = summable_Leibniz'[OF `a ----> 0` ge0] and mono = this
|
hoelzl@29740
|
289 |
from leibniz[OF mono]
|
hoelzl@29740
|
290 |
show ?thesis using `0 \<le> a 0` by auto
|
hoelzl@29740
|
291 |
next
|
hoelzl@29740
|
292 |
let ?a = "\<lambda> n. - a n"
|
hoelzl@29740
|
293 |
case False
|
hoelzl@29740
|
294 |
with monoseq_le[OF `monoseq a` `a ----> 0`]
|
hoelzl@29740
|
295 |
have "(\<forall> n. a n \<le> 0) \<and> (\<forall>m. \<forall>n\<ge>m. a m \<le> a n)" by auto
|
hoelzl@29740
|
296 |
hence ord: "\<And>n m. m \<le> n \<Longrightarrow> ?a n \<le> ?a m" and ge0: "\<And> n. 0 \<le> ?a n" by auto
|
hoelzl@29740
|
297 |
{ fix n have "?a (Suc n) \<le> ?a n" using ord[where n="Suc n" and m=n] by auto }
|
hoelzl@29740
|
298 |
note monotone = this
|
hoelzl@29740
|
299 |
note leibniz = summable_Leibniz'[OF _ ge0, of "\<lambda>x. x", OF LIMSEQ_minus[OF `a ----> 0`, unfolded minus_zero] monotone]
|
hoelzl@29740
|
300 |
have "summable (\<lambda> n. (-1)^n * ?a n)" using leibniz(1) by auto
|
hoelzl@29740
|
301 |
then obtain l where "(\<lambda> n. (-1)^n * ?a n) sums l" unfolding summable_def by auto
|
hoelzl@29740
|
302 |
from this[THEN sums_minus]
|
hoelzl@29740
|
303 |
have "(\<lambda> n. (-1)^n * a n) sums -l" by auto
|
hoelzl@29740
|
304 |
hence ?summable unfolding summable_def by auto
|
hoelzl@29740
|
305 |
moreover
|
hoelzl@29740
|
306 |
have "\<And> a b :: real. \<bar> - a - - b \<bar> = \<bar>a - b\<bar>" unfolding minus_diff_minus by auto
|
hoelzl@29740
|
307 |
|
hoelzl@29740
|
308 |
from suminf_minus[OF leibniz(1), unfolded mult_minus_right minus_minus]
|
hoelzl@29740
|
309 |
have move_minus: "(\<Sum>n. - (-1 ^ n * a n)) = - (\<Sum>n. -1 ^ n * a n)" by auto
|
hoelzl@29740
|
310 |
|
hoelzl@29740
|
311 |
have ?pos using `0 \<le> ?a 0` by auto
|
hoelzl@29740
|
312 |
moreover have ?neg using leibniz(2,4) unfolding mult_minus_right setsum_negf move_minus neg_le_iff_le by auto
|
hoelzl@29740
|
313 |
moreover have ?f and ?g using leibniz(3,5)[unfolded mult_minus_right setsum_negf move_minus, THEN LIMSEQ_minus_cancel] by auto
|
hoelzl@29740
|
314 |
ultimately show ?thesis by auto
|
hoelzl@29740
|
315 |
qed
|
hoelzl@29740
|
316 |
from this[THEN conjunct1] this[THEN conjunct2, THEN conjunct1] this[THEN conjunct2, THEN conjunct2, THEN conjunct1] this[THEN conjunct2, THEN conjunct2, THEN conjunct2, THEN conjunct1]
|
hoelzl@29740
|
317 |
this[THEN conjunct2, THEN conjunct2, THEN conjunct2, THEN conjunct2]
|
hoelzl@29740
|
318 |
show ?summable and ?pos and ?neg and ?f and ?g .
|
hoelzl@29740
|
319 |
qed
|
paulson@15077
|
320 |
|
huffman@29164
|
321 |
subsection {* Term-by-Term Differentiability of Power Series *}
|
huffman@23043
|
322 |
|
huffman@23043
|
323 |
definition
|
huffman@23082
|
324 |
diffs :: "(nat => 'a::ring_1) => nat => 'a" where
|
huffman@23082
|
325 |
"diffs c = (%n. of_nat (Suc n) * c(Suc n))"
|
paulson@15077
|
326 |
|
paulson@15077
|
327 |
text{*Lemma about distributing negation over it*}
|
paulson@15077
|
328 |
lemma diffs_minus: "diffs (%n. - c n) = (%n. - diffs c n)"
|
paulson@15077
|
329 |
by (simp add: diffs_def)
|
paulson@15077
|
330 |
|
huffman@29163
|
331 |
lemma sums_Suc_imp:
|
huffman@29163
|
332 |
assumes f: "f 0 = 0"
|
huffman@29163
|
333 |
shows "(\<lambda>n. f (Suc n)) sums s \<Longrightarrow> (\<lambda>n. f n) sums s"
|
huffman@29163
|
334 |
unfolding sums_def
|
huffman@29163
|
335 |
apply (rule LIMSEQ_imp_Suc)
|
huffman@29163
|
336 |
apply (subst setsum_shift_lb_Suc0_0_upt [where f=f, OF f, symmetric])
|
huffman@29163
|
337 |
apply (simp only: setsum_shift_bounds_Suc_ivl)
|
paulson@15077
|
338 |
done
|
paulson@15077
|
339 |
|
paulson@15229
|
340 |
lemma diffs_equiv:
|
paulson@15229
|
341 |
"summable (%n. (diffs c)(n) * (x ^ n)) ==>
|
huffman@23082
|
342 |
(%n. of_nat n * c(n) * (x ^ (n - Suc 0))) sums
|
nipkow@15546
|
343 |
(\<Sum>n. (diffs c)(n) * (x ^ n))"
|
huffman@29163
|
344 |
unfolding diffs_def
|
huffman@29163
|
345 |
apply (drule summable_sums)
|
huffman@29163
|
346 |
apply (rule sums_Suc_imp, simp_all)
|
paulson@15077
|
347 |
done
|
paulson@15077
|
348 |
|
paulson@15077
|
349 |
lemma lemma_termdiff1:
|
haftmann@31017
|
350 |
fixes z :: "'a :: {monoid_mult,comm_ring}" shows
|
nipkow@15539
|
351 |
"(\<Sum>p=0..<m. (((z + h) ^ (m - p)) * (z ^ p)) - (z ^ m)) =
|
huffman@23082
|
352 |
(\<Sum>p=0..<m. (z ^ p) * (((z + h) ^ (m - p)) - (z ^ (m - p))))"
|
nipkow@29667
|
353 |
by(auto simp add: algebra_simps power_add [symmetric] cong: strong_setsum_cong)
|
paulson@15077
|
354 |
|
huffman@23082
|
355 |
lemma sumr_diff_mult_const2:
|
huffman@23082
|
356 |
"setsum f {0..<n} - of_nat n * (r::'a::ring_1) = (\<Sum>i = 0..<n. f i - r)"
|
huffman@23082
|
357 |
by (simp add: setsum_subtractf)
|
huffman@23082
|
358 |
|
huffman@20860
|
359 |
lemma lemma_termdiff2:
|
haftmann@31017
|
360 |
fixes h :: "'a :: {field}"
|
huffman@20860
|
361 |
assumes h: "h \<noteq> 0" shows
|
huffman@23082
|
362 |
"((z + h) ^ n - z ^ n) / h - of_nat n * z ^ (n - Suc 0) =
|
huffman@20860
|
363 |
h * (\<Sum>p=0..< n - Suc 0. \<Sum>q=0..< n - Suc 0 - p.
|
huffman@23082
|
364 |
(z + h) ^ q * z ^ (n - 2 - q))" (is "?lhs = ?rhs")
|
huffman@23082
|
365 |
apply (subgoal_tac "h * ?lhs = h * ?rhs", simp add: h)
|
huffman@20860
|
366 |
apply (simp add: right_diff_distrib diff_divide_distrib h)
|
huffman@20860
|
367 |
apply (simp add: mult_assoc [symmetric])
|
huffman@20860
|
368 |
apply (cases "n", simp)
|
huffman@20860
|
369 |
apply (simp add: lemma_realpow_diff_sumr2 h
|
huffman@20860
|
370 |
right_diff_distrib [symmetric] mult_assoc
|
huffman@30269
|
371 |
del: power_Suc setsum_op_ivl_Suc of_nat_Suc)
|
huffman@20860
|
372 |
apply (subst lemma_realpow_rev_sumr)
|
huffman@23082
|
373 |
apply (subst sumr_diff_mult_const2)
|
huffman@20860
|
374 |
apply simp
|
huffman@20860
|
375 |
apply (simp only: lemma_termdiff1 setsum_right_distrib)
|
huffman@20860
|
376 |
apply (rule setsum_cong [OF refl])
|
huffman@20860
|
377 |
apply (simp add: diff_minus [symmetric] less_iff_Suc_add)
|
huffman@20860
|
378 |
apply (clarify)
|
huffman@20860
|
379 |
apply (simp add: setsum_right_distrib lemma_realpow_diff_sumr2 mult_ac
|
huffman@30269
|
380 |
del: setsum_op_ivl_Suc power_Suc)
|
huffman@20860
|
381 |
apply (subst mult_assoc [symmetric], subst power_add [symmetric])
|
huffman@20860
|
382 |
apply (simp add: mult_ac)
|
huffman@20860
|
383 |
done
|
paulson@15077
|
384 |
|
huffman@20860
|
385 |
lemma real_setsum_nat_ivl_bounded2:
|
huffman@23082
|
386 |
fixes K :: "'a::ordered_semidom"
|
huffman@23082
|
387 |
assumes f: "\<And>p::nat. p < n \<Longrightarrow> f p \<le> K"
|
huffman@23082
|
388 |
assumes K: "0 \<le> K"
|
huffman@23082
|
389 |
shows "setsum f {0..<n-k} \<le> of_nat n * K"
|
huffman@23082
|
390 |
apply (rule order_trans [OF setsum_mono])
|
huffman@23082
|
391 |
apply (rule f, simp)
|
huffman@23082
|
392 |
apply (simp add: mult_right_mono K)
|
paulson@15077
|
393 |
done
|
paulson@15077
|
394 |
|
paulson@15229
|
395 |
lemma lemma_termdiff3:
|
haftmann@31017
|
396 |
fixes h z :: "'a::{real_normed_field}"
|
huffman@20860
|
397 |
assumes 1: "h \<noteq> 0"
|
huffman@23082
|
398 |
assumes 2: "norm z \<le> K"
|
huffman@23082
|
399 |
assumes 3: "norm (z + h) \<le> K"
|
huffman@23082
|
400 |
shows "norm (((z + h) ^ n - z ^ n) / h - of_nat n * z ^ (n - Suc 0))
|
huffman@23082
|
401 |
\<le> of_nat n * of_nat (n - Suc 0) * K ^ (n - 2) * norm h"
|
huffman@20860
|
402 |
proof -
|
huffman@23082
|
403 |
have "norm (((z + h) ^ n - z ^ n) / h - of_nat n * z ^ (n - Suc 0)) =
|
huffman@23082
|
404 |
norm (\<Sum>p = 0..<n - Suc 0. \<Sum>q = 0..<n - Suc 0 - p.
|
huffman@23082
|
405 |
(z + h) ^ q * z ^ (n - 2 - q)) * norm h"
|
huffman@20860
|
406 |
apply (subst lemma_termdiff2 [OF 1])
|
huffman@23082
|
407 |
apply (subst norm_mult)
|
huffman@20860
|
408 |
apply (rule mult_commute)
|
huffman@20860
|
409 |
done
|
huffman@23082
|
410 |
also have "\<dots> \<le> of_nat n * (of_nat (n - Suc 0) * K ^ (n - 2)) * norm h"
|
huffman@23082
|
411 |
proof (rule mult_right_mono [OF _ norm_ge_zero])
|
huffman@23082
|
412 |
from norm_ge_zero 2 have K: "0 \<le> K" by (rule order_trans)
|
huffman@23082
|
413 |
have le_Kn: "\<And>i j n. i + j = n \<Longrightarrow> norm ((z + h) ^ i * z ^ j) \<le> K ^ n"
|
huffman@20860
|
414 |
apply (erule subst)
|
huffman@23082
|
415 |
apply (simp only: norm_mult norm_power power_add)
|
huffman@23082
|
416 |
apply (intro mult_mono power_mono 2 3 norm_ge_zero zero_le_power K)
|
huffman@20860
|
417 |
done
|
huffman@23082
|
418 |
show "norm (\<Sum>p = 0..<n - Suc 0. \<Sum>q = 0..<n - Suc 0 - p.
|
huffman@23082
|
419 |
(z + h) ^ q * z ^ (n - 2 - q))
|
huffman@23082
|
420 |
\<le> of_nat n * (of_nat (n - Suc 0) * K ^ (n - 2))"
|
huffman@20860
|
421 |
apply (intro
|
huffman@23082
|
422 |
order_trans [OF norm_setsum]
|
huffman@20860
|
423 |
real_setsum_nat_ivl_bounded2
|
huffman@20860
|
424 |
mult_nonneg_nonneg
|
huffman@23082
|
425 |
zero_le_imp_of_nat
|
huffman@20860
|
426 |
zero_le_power K)
|
huffman@20860
|
427 |
apply (rule le_Kn, simp)
|
huffman@20860
|
428 |
done
|
huffman@20860
|
429 |
qed
|
huffman@23082
|
430 |
also have "\<dots> = of_nat n * of_nat (n - Suc 0) * K ^ (n - 2) * norm h"
|
huffman@20860
|
431 |
by (simp only: mult_assoc)
|
huffman@20860
|
432 |
finally show ?thesis .
|
huffman@20860
|
433 |
qed
|
paulson@15077
|
434 |
|
huffman@20860
|
435 |
lemma lemma_termdiff4:
|
haftmann@31017
|
436 |
fixes f :: "'a::{real_normed_field} \<Rightarrow>
|
huffman@23082
|
437 |
'b::real_normed_vector"
|
huffman@20860
|
438 |
assumes k: "0 < (k::real)"
|
huffman@23082
|
439 |
assumes le: "\<And>h. \<lbrakk>h \<noteq> 0; norm h < k\<rbrakk> \<Longrightarrow> norm (f h) \<le> K * norm h"
|
huffman@20860
|
440 |
shows "f -- 0 --> 0"
|
huffman@31325
|
441 |
unfolding LIM_eq diff_0_right
|
huffman@29163
|
442 |
proof (safe)
|
huffman@29163
|
443 |
let ?h = "of_real (k / 2)::'a"
|
huffman@29163
|
444 |
have "?h \<noteq> 0" and "norm ?h < k" using k by simp_all
|
huffman@29163
|
445 |
hence "norm (f ?h) \<le> K * norm ?h" by (rule le)
|
huffman@29163
|
446 |
hence "0 \<le> K * norm ?h" by (rule order_trans [OF norm_ge_zero])
|
huffman@29163
|
447 |
hence zero_le_K: "0 \<le> K" using k by (simp add: zero_le_mult_iff)
|
huffman@29163
|
448 |
|
huffman@20860
|
449 |
fix r::real assume r: "0 < r"
|
huffman@23082
|
450 |
show "\<exists>s. 0 < s \<and> (\<forall>x. x \<noteq> 0 \<and> norm x < s \<longrightarrow> norm (f x) < r)"
|
huffman@20860
|
451 |
proof (cases)
|
huffman@20860
|
452 |
assume "K = 0"
|
huffman@23082
|
453 |
with k r le have "0 < k \<and> (\<forall>x. x \<noteq> 0 \<and> norm x < k \<longrightarrow> norm (f x) < r)"
|
huffman@20860
|
454 |
by simp
|
huffman@23082
|
455 |
thus "\<exists>s. 0 < s \<and> (\<forall>x. x \<noteq> 0 \<and> norm x < s \<longrightarrow> norm (f x) < r)" ..
|
huffman@20860
|
456 |
next
|
huffman@20860
|
457 |
assume K_neq_zero: "K \<noteq> 0"
|
huffman@20860
|
458 |
with zero_le_K have K: "0 < K" by simp
|
huffman@23082
|
459 |
show "\<exists>s. 0 < s \<and> (\<forall>x. x \<noteq> 0 \<and> norm x < s \<longrightarrow> norm (f x) < r)"
|
huffman@20860
|
460 |
proof (rule exI, safe)
|
huffman@20860
|
461 |
from k r K show "0 < min k (r * inverse K / 2)"
|
huffman@20860
|
462 |
by (simp add: mult_pos_pos positive_imp_inverse_positive)
|
huffman@20860
|
463 |
next
|
huffman@23082
|
464 |
fix x::'a
|
huffman@23082
|
465 |
assume x1: "x \<noteq> 0" and x2: "norm x < min k (r * inverse K / 2)"
|
huffman@23082
|
466 |
from x2 have x3: "norm x < k" and x4: "norm x < r * inverse K / 2"
|
huffman@20860
|
467 |
by simp_all
|
huffman@23082
|
468 |
from x1 x3 le have "norm (f x) \<le> K * norm x" by simp
|
huffman@23082
|
469 |
also from x4 K have "K * norm x < K * (r * inverse K / 2)"
|
huffman@20860
|
470 |
by (rule mult_strict_left_mono)
|
huffman@20860
|
471 |
also have "\<dots> = r / 2"
|
huffman@20860
|
472 |
using K_neq_zero by simp
|
huffman@20860
|
473 |
also have "r / 2 < r"
|
huffman@20860
|
474 |
using r by simp
|
huffman@23082
|
475 |
finally show "norm (f x) < r" .
|
huffman@20860
|
476 |
qed
|
huffman@20860
|
477 |
qed
|
huffman@20860
|
478 |
qed
|
paulson@15077
|
479 |
|
paulson@15229
|
480 |
lemma lemma_termdiff5:
|
haftmann@31017
|
481 |
fixes g :: "'a::{real_normed_field} \<Rightarrow>
|
huffman@23082
|
482 |
nat \<Rightarrow> 'b::banach"
|
huffman@20860
|
483 |
assumes k: "0 < (k::real)"
|
huffman@20860
|
484 |
assumes f: "summable f"
|
huffman@23082
|
485 |
assumes le: "\<And>h n. \<lbrakk>h \<noteq> 0; norm h < k\<rbrakk> \<Longrightarrow> norm (g h n) \<le> f n * norm h"
|
huffman@20860
|
486 |
shows "(\<lambda>h. suminf (g h)) -- 0 --> 0"
|
huffman@20860
|
487 |
proof (rule lemma_termdiff4 [OF k])
|
huffman@23082
|
488 |
fix h::'a assume "h \<noteq> 0" and "norm h < k"
|
huffman@23082
|
489 |
hence A: "\<forall>n. norm (g h n) \<le> f n * norm h"
|
huffman@20860
|
490 |
by (simp add: le)
|
huffman@23082
|
491 |
hence "\<exists>N. \<forall>n\<ge>N. norm (norm (g h n)) \<le> f n * norm h"
|
huffman@20860
|
492 |
by simp
|
huffman@23082
|
493 |
moreover from f have B: "summable (\<lambda>n. f n * norm h)"
|
huffman@20860
|
494 |
by (rule summable_mult2)
|
huffman@23082
|
495 |
ultimately have C: "summable (\<lambda>n. norm (g h n))"
|
huffman@20860
|
496 |
by (rule summable_comparison_test)
|
huffman@23082
|
497 |
hence "norm (suminf (g h)) \<le> (\<Sum>n. norm (g h n))"
|
huffman@23082
|
498 |
by (rule summable_norm)
|
huffman@23082
|
499 |
also from A C B have "(\<Sum>n. norm (g h n)) \<le> (\<Sum>n. f n * norm h)"
|
huffman@20860
|
500 |
by (rule summable_le)
|
huffman@23082
|
501 |
also from f have "(\<Sum>n. f n * norm h) = suminf f * norm h"
|
huffman@20860
|
502 |
by (rule suminf_mult2 [symmetric])
|
huffman@23082
|
503 |
finally show "norm (suminf (g h)) \<le> suminf f * norm h" .
|
huffman@20860
|
504 |
qed
|
paulson@15077
|
505 |
|
paulson@15077
|
506 |
|
paulson@15077
|
507 |
text{* FIXME: Long proofs*}
|
paulson@15077
|
508 |
|
paulson@15077
|
509 |
lemma termdiffs_aux:
|
haftmann@31017
|
510 |
fixes x :: "'a::{real_normed_field,banach}"
|
huffman@20849
|
511 |
assumes 1: "summable (\<lambda>n. diffs (diffs c) n * K ^ n)"
|
huffman@23082
|
512 |
assumes 2: "norm x < norm K"
|
huffman@20860
|
513 |
shows "(\<lambda>h. \<Sum>n. c n * (((x + h) ^ n - x ^ n) / h
|
huffman@23082
|
514 |
- of_nat n * x ^ (n - Suc 0))) -- 0 --> 0"
|
huffman@20849
|
515 |
proof -
|
huffman@20860
|
516 |
from dense [OF 2]
|
huffman@23082
|
517 |
obtain r where r1: "norm x < r" and r2: "r < norm K" by fast
|
huffman@23082
|
518 |
from norm_ge_zero r1 have r: "0 < r"
|
huffman@20860
|
519 |
by (rule order_le_less_trans)
|
huffman@20860
|
520 |
hence r_neq_0: "r \<noteq> 0" by simp
|
huffman@20860
|
521 |
show ?thesis
|
huffman@20849
|
522 |
proof (rule lemma_termdiff5)
|
huffman@23082
|
523 |
show "0 < r - norm x" using r1 by simp
|
huffman@20849
|
524 |
next
|
huffman@23082
|
525 |
from r r2 have "norm (of_real r::'a) < norm K"
|
huffman@23082
|
526 |
by simp
|
huffman@23082
|
527 |
with 1 have "summable (\<lambda>n. norm (diffs (diffs c) n * (of_real r ^ n)))"
|
huffman@20860
|
528 |
by (rule powser_insidea)
|
huffman@23082
|
529 |
hence "summable (\<lambda>n. diffs (diffs (\<lambda>n. norm (c n))) n * r ^ n)"
|
huffman@23082
|
530 |
using r
|
huffman@23082
|
531 |
by (simp add: diffs_def norm_mult norm_power del: of_nat_Suc)
|
huffman@23082
|
532 |
hence "summable (\<lambda>n. of_nat n * diffs (\<lambda>n. norm (c n)) n * r ^ (n - Suc 0))"
|
huffman@20860
|
533 |
by (rule diffs_equiv [THEN sums_summable])
|
huffman@23082
|
534 |
also have "(\<lambda>n. of_nat n * diffs (\<lambda>n. norm (c n)) n * r ^ (n - Suc 0))
|
huffman@23082
|
535 |
= (\<lambda>n. diffs (%m. of_nat (m - Suc 0) * norm (c m) * inverse r) n * (r ^ n))"
|
huffman@20849
|
536 |
apply (rule ext)
|
huffman@20849
|
537 |
apply (simp add: diffs_def)
|
huffman@20849
|
538 |
apply (case_tac n, simp_all add: r_neq_0)
|
huffman@20849
|
539 |
done
|
huffman@20860
|
540 |
finally have "summable
|
huffman@23082
|
541 |
(\<lambda>n. of_nat n * (of_nat (n - Suc 0) * norm (c n) * inverse r) * r ^ (n - Suc 0))"
|
huffman@20860
|
542 |
by (rule diffs_equiv [THEN sums_summable])
|
huffman@20860
|
543 |
also have
|
huffman@23082
|
544 |
"(\<lambda>n. of_nat n * (of_nat (n - Suc 0) * norm (c n) * inverse r) *
|
huffman@20860
|
545 |
r ^ (n - Suc 0)) =
|
huffman@23082
|
546 |
(\<lambda>n. norm (c n) * of_nat n * of_nat (n - Suc 0) * r ^ (n - 2))"
|
huffman@20849
|
547 |
apply (rule ext)
|
huffman@20849
|
548 |
apply (case_tac "n", simp)
|
huffman@20849
|
549 |
apply (case_tac "nat", simp)
|
huffman@20849
|
550 |
apply (simp add: r_neq_0)
|
huffman@20849
|
551 |
done
|
huffman@20860
|
552 |
finally show
|
huffman@23082
|
553 |
"summable (\<lambda>n. norm (c n) * of_nat n * of_nat (n - Suc 0) * r ^ (n - 2))" .
|
huffman@20860
|
554 |
next
|
huffman@23082
|
555 |
fix h::'a and n::nat
|
huffman@20860
|
556 |
assume h: "h \<noteq> 0"
|
huffman@23082
|
557 |
assume "norm h < r - norm x"
|
huffman@23082
|
558 |
hence "norm x + norm h < r" by simp
|
huffman@23082
|
559 |
with norm_triangle_ineq have xh: "norm (x + h) < r"
|
huffman@20860
|
560 |
by (rule order_le_less_trans)
|
huffman@23082
|
561 |
show "norm (c n * (((x + h) ^ n - x ^ n) / h - of_nat n * x ^ (n - Suc 0)))
|
huffman@23082
|
562 |
\<le> norm (c n) * of_nat n * of_nat (n - Suc 0) * r ^ (n - 2) * norm h"
|
huffman@23082
|
563 |
apply (simp only: norm_mult mult_assoc)
|
huffman@23082
|
564 |
apply (rule mult_left_mono [OF _ norm_ge_zero])
|
huffman@20860
|
565 |
apply (simp (no_asm) add: mult_assoc [symmetric])
|
huffman@20860
|
566 |
apply (rule lemma_termdiff3)
|
huffman@20860
|
567 |
apply (rule h)
|
huffman@20860
|
568 |
apply (rule r1 [THEN order_less_imp_le])
|
huffman@20860
|
569 |
apply (rule xh [THEN order_less_imp_le])
|
huffman@20849
|
570 |
done
|
huffman@20849
|
571 |
qed
|
huffman@20849
|
572 |
qed
|
webertj@20217
|
573 |
|
huffman@20860
|
574 |
lemma termdiffs:
|
haftmann@31017
|
575 |
fixes K x :: "'a::{real_normed_field,banach}"
|
huffman@20860
|
576 |
assumes 1: "summable (\<lambda>n. c n * K ^ n)"
|
huffman@20860
|
577 |
assumes 2: "summable (\<lambda>n. (diffs c) n * K ^ n)"
|
huffman@20860
|
578 |
assumes 3: "summable (\<lambda>n. (diffs (diffs c)) n * K ^ n)"
|
huffman@23082
|
579 |
assumes 4: "norm x < norm K"
|
huffman@20860
|
580 |
shows "DERIV (\<lambda>x. \<Sum>n. c n * x ^ n) x :> (\<Sum>n. (diffs c) n * x ^ n)"
|
huffman@29163
|
581 |
unfolding deriv_def
|
huffman@29163
|
582 |
proof (rule LIM_zero_cancel)
|
huffman@20860
|
583 |
show "(\<lambda>h. (suminf (\<lambda>n. c n * (x + h) ^ n) - suminf (\<lambda>n. c n * x ^ n)) / h
|
huffman@20860
|
584 |
- suminf (\<lambda>n. diffs c n * x ^ n)) -- 0 --> 0"
|
huffman@20860
|
585 |
proof (rule LIM_equal2)
|
huffman@29163
|
586 |
show "0 < norm K - norm x" using 4 by (simp add: less_diff_eq)
|
huffman@20860
|
587 |
next
|
huffman@23082
|
588 |
fix h :: 'a
|
huffman@20860
|
589 |
assume "h \<noteq> 0"
|
huffman@23082
|
590 |
assume "norm (h - 0) < norm K - norm x"
|
huffman@23082
|
591 |
hence "norm x + norm h < norm K" by simp
|
huffman@23082
|
592 |
hence 5: "norm (x + h) < norm K"
|
huffman@23082
|
593 |
by (rule norm_triangle_ineq [THEN order_le_less_trans])
|
huffman@20860
|
594 |
have A: "summable (\<lambda>n. c n * x ^ n)"
|
huffman@20860
|
595 |
by (rule powser_inside [OF 1 4])
|
huffman@20860
|
596 |
have B: "summable (\<lambda>n. c n * (x + h) ^ n)"
|
huffman@20860
|
597 |
by (rule powser_inside [OF 1 5])
|
huffman@20860
|
598 |
have C: "summable (\<lambda>n. diffs c n * x ^ n)"
|
huffman@20860
|
599 |
by (rule powser_inside [OF 2 4])
|
huffman@20860
|
600 |
show "((\<Sum>n. c n * (x + h) ^ n) - (\<Sum>n. c n * x ^ n)) / h
|
huffman@20860
|
601 |
- (\<Sum>n. diffs c n * x ^ n) =
|
huffman@23082
|
602 |
(\<Sum>n. c n * (((x + h) ^ n - x ^ n) / h - of_nat n * x ^ (n - Suc 0)))"
|
huffman@20860
|
603 |
apply (subst sums_unique [OF diffs_equiv [OF C]])
|
huffman@20860
|
604 |
apply (subst suminf_diff [OF B A])
|
huffman@20860
|
605 |
apply (subst suminf_divide [symmetric])
|
huffman@20860
|
606 |
apply (rule summable_diff [OF B A])
|
huffman@20860
|
607 |
apply (subst suminf_diff)
|
huffman@20860
|
608 |
apply (rule summable_divide)
|
huffman@20860
|
609 |
apply (rule summable_diff [OF B A])
|
huffman@20860
|
610 |
apply (rule sums_summable [OF diffs_equiv [OF C]])
|
huffman@29163
|
611 |
apply (rule arg_cong [where f="suminf"], rule ext)
|
nipkow@29667
|
612 |
apply (simp add: algebra_simps)
|
huffman@20860
|
613 |
done
|
huffman@20860
|
614 |
next
|
huffman@20860
|
615 |
show "(\<lambda>h. \<Sum>n. c n * (((x + h) ^ n - x ^ n) / h -
|
huffman@23082
|
616 |
of_nat n * x ^ (n - Suc 0))) -- 0 --> 0"
|
huffman@20860
|
617 |
by (rule termdiffs_aux [OF 3 4])
|
huffman@20860
|
618 |
qed
|
huffman@20860
|
619 |
qed
|
huffman@20860
|
620 |
|
paulson@15077
|
621 |
|
chaieb@29695
|
622 |
subsection{* Some properties of factorials *}
|
chaieb@29695
|
623 |
|
chaieb@29695
|
624 |
lemma real_of_nat_fact_not_zero [simp]: "real (fact n) \<noteq> 0"
|
chaieb@29695
|
625 |
by auto
|
chaieb@29695
|
626 |
|
chaieb@29695
|
627 |
lemma real_of_nat_fact_gt_zero [simp]: "0 < real(fact n)"
|
chaieb@29695
|
628 |
by auto
|
chaieb@29695
|
629 |
|
chaieb@29695
|
630 |
lemma real_of_nat_fact_ge_zero [simp]: "0 \<le> real(fact n)"
|
chaieb@29695
|
631 |
by simp
|
chaieb@29695
|
632 |
|
chaieb@29695
|
633 |
lemma inv_real_of_nat_fact_gt_zero [simp]: "0 < inverse (real (fact n))"
|
chaieb@29695
|
634 |
by (auto simp add: positive_imp_inverse_positive)
|
chaieb@29695
|
635 |
|
chaieb@29695
|
636 |
lemma inv_real_of_nat_fact_ge_zero [simp]: "0 \<le> inverse (real (fact n))"
|
chaieb@29695
|
637 |
by (auto intro: order_less_imp_le)
|
chaieb@29695
|
638 |
|
hoelzl@29740
|
639 |
subsection {* Derivability of power series *}
|
hoelzl@29740
|
640 |
|
hoelzl@29740
|
641 |
lemma DERIV_series': fixes f :: "real \<Rightarrow> nat \<Rightarrow> real"
|
hoelzl@29740
|
642 |
assumes DERIV_f: "\<And> n. DERIV (\<lambda> x. f x n) x0 :> (f' x0 n)"
|
hoelzl@29740
|
643 |
and allf_summable: "\<And> x. x \<in> {a <..< b} \<Longrightarrow> summable (f x)" and x0_in_I: "x0 \<in> {a <..< b}"
|
hoelzl@29740
|
644 |
and "summable (f' x0)"
|
hoelzl@29740
|
645 |
and "summable L" and L_def: "\<And> n x y. \<lbrakk> x \<in> { a <..< b} ; y \<in> { a <..< b} \<rbrakk> \<Longrightarrow> \<bar> f x n - f y n \<bar> \<le> L n * \<bar> x - y \<bar>"
|
hoelzl@29740
|
646 |
shows "DERIV (\<lambda> x. suminf (f x)) x0 :> (suminf (f' x0))"
|
hoelzl@29740
|
647 |
unfolding deriv_def
|
hoelzl@29740
|
648 |
proof (rule LIM_I)
|
hoelzl@29740
|
649 |
fix r :: real assume "0 < r" hence "0 < r/3" by auto
|
hoelzl@29740
|
650 |
|
hoelzl@29740
|
651 |
obtain N_L where N_L: "\<And> n. N_L \<le> n \<Longrightarrow> \<bar> \<Sum> i. L (i + n) \<bar> < r/3"
|
hoelzl@29740
|
652 |
using suminf_exist_split[OF `0 < r/3` `summable L`] by auto
|
hoelzl@29740
|
653 |
|
hoelzl@29740
|
654 |
obtain N_f' where N_f': "\<And> n. N_f' \<le> n \<Longrightarrow> \<bar> \<Sum> i. f' x0 (i + n) \<bar> < r/3"
|
hoelzl@29740
|
655 |
using suminf_exist_split[OF `0 < r/3` `summable (f' x0)`] by auto
|
hoelzl@29740
|
656 |
|
hoelzl@29740
|
657 |
let ?N = "Suc (max N_L N_f')"
|
hoelzl@29740
|
658 |
have "\<bar> \<Sum> i. f' x0 (i + ?N) \<bar> < r/3" (is "?f'_part < r/3") and
|
hoelzl@29740
|
659 |
L_estimate: "\<bar> \<Sum> i. L (i + ?N) \<bar> < r/3" using N_L[of "?N"] and N_f' [of "?N"] by auto
|
hoelzl@29740
|
660 |
|
hoelzl@29740
|
661 |
let "?diff i x" = "(f (x0 + x) i - f x0 i) / x"
|
hoelzl@29740
|
662 |
|
hoelzl@29740
|
663 |
let ?r = "r / (3 * real ?N)"
|
hoelzl@29740
|
664 |
have "0 < 3 * real ?N" by auto
|
hoelzl@29740
|
665 |
from divide_pos_pos[OF `0 < r` this]
|
hoelzl@29740
|
666 |
have "0 < ?r" .
|
hoelzl@29740
|
667 |
|
hoelzl@29740
|
668 |
let "?s n" = "SOME s. 0 < s \<and> (\<forall> x. x \<noteq> 0 \<and> \<bar> x \<bar> < s \<longrightarrow> \<bar> ?diff n x - f' x0 n \<bar> < ?r)"
|
hoelzl@29740
|
669 |
def S' \<equiv> "Min (?s ` { 0 ..< ?N })"
|
hoelzl@29740
|
670 |
|
hoelzl@29740
|
671 |
have "0 < S'" unfolding S'_def
|
hoelzl@29740
|
672 |
proof (rule iffD2[OF Min_gr_iff])
|
hoelzl@29740
|
673 |
show "\<forall> x \<in> (?s ` { 0 ..< ?N }). 0 < x"
|
hoelzl@29740
|
674 |
proof (rule ballI)
|
hoelzl@29740
|
675 |
fix x assume "x \<in> ?s ` {0..<?N}"
|
hoelzl@29740
|
676 |
then obtain n where "x = ?s n" and "n \<in> {0..<?N}" using image_iff[THEN iffD1] by blast
|
hoelzl@29740
|
677 |
from DERIV_D[OF DERIV_f[where n=n], THEN LIM_D, OF `0 < ?r`, unfolded real_norm_def]
|
hoelzl@29740
|
678 |
obtain s where s_bound: "0 < s \<and> (\<forall>x. x \<noteq> 0 \<and> \<bar>x\<bar> < s \<longrightarrow> \<bar>?diff n x - f' x0 n\<bar> < ?r)" by auto
|
hoelzl@29740
|
679 |
have "0 < ?s n" by (rule someI2[where a=s], auto simp add: s_bound)
|
hoelzl@29740
|
680 |
thus "0 < x" unfolding `x = ?s n` .
|
hoelzl@29740
|
681 |
qed
|
hoelzl@29740
|
682 |
qed auto
|
hoelzl@29740
|
683 |
|
hoelzl@29740
|
684 |
def S \<equiv> "min (min (x0 - a) (b - x0)) S'"
|
hoelzl@29740
|
685 |
hence "0 < S" and S_a: "S \<le> x0 - a" and S_b: "S \<le> b - x0" and "S \<le> S'" using x0_in_I and `0 < S'`
|
hoelzl@29740
|
686 |
by auto
|
hoelzl@29740
|
687 |
|
hoelzl@29740
|
688 |
{ fix x assume "x \<noteq> 0" and "\<bar> x \<bar> < S"
|
hoelzl@29740
|
689 |
hence x_in_I: "x0 + x \<in> { a <..< b }" using S_a S_b by auto
|
hoelzl@29740
|
690 |
|
hoelzl@29740
|
691 |
note diff_smbl = summable_diff[OF allf_summable[OF x_in_I] allf_summable[OF x0_in_I]]
|
hoelzl@29740
|
692 |
note div_smbl = summable_divide[OF diff_smbl]
|
hoelzl@29740
|
693 |
note all_smbl = summable_diff[OF div_smbl `summable (f' x0)`]
|
hoelzl@29740
|
694 |
note ign = summable_ignore_initial_segment[where k="?N"]
|
hoelzl@29740
|
695 |
note diff_shft_smbl = summable_diff[OF ign[OF allf_summable[OF x_in_I]] ign[OF allf_summable[OF x0_in_I]]]
|
hoelzl@29740
|
696 |
note div_shft_smbl = summable_divide[OF diff_shft_smbl]
|
hoelzl@29740
|
697 |
note all_shft_smbl = summable_diff[OF div_smbl ign[OF `summable (f' x0)`]]
|
hoelzl@29740
|
698 |
|
hoelzl@29740
|
699 |
{ fix n
|
hoelzl@29740
|
700 |
have "\<bar> ?diff (n + ?N) x \<bar> \<le> L (n + ?N) * \<bar> (x0 + x) - x0 \<bar> / \<bar> x \<bar>"
|
hoelzl@29740
|
701 |
using divide_right_mono[OF L_def[OF x_in_I x0_in_I] abs_ge_zero] unfolding abs_divide .
|
hoelzl@29740
|
702 |
hence "\<bar> ( \<bar> ?diff (n + ?N) x \<bar>) \<bar> \<le> L (n + ?N)" using `x \<noteq> 0` by auto
|
hoelzl@29740
|
703 |
} note L_ge = summable_le2[OF allI[OF this] ign[OF `summable L`]]
|
hoelzl@29740
|
704 |
from order_trans[OF summable_rabs[OF conjunct1[OF L_ge]] L_ge[THEN conjunct2]]
|
hoelzl@29740
|
705 |
have "\<bar> \<Sum> i. ?diff (i + ?N) x \<bar> \<le> (\<Sum> i. L (i + ?N))" .
|
hoelzl@29740
|
706 |
hence "\<bar> \<Sum> i. ?diff (i + ?N) x \<bar> \<le> r / 3" (is "?L_part \<le> r/3") using L_estimate by auto
|
hoelzl@29740
|
707 |
|
hoelzl@29740
|
708 |
have "\<bar>\<Sum>n \<in> { 0 ..< ?N}. ?diff n x - f' x0 n \<bar> \<le> (\<Sum>n \<in> { 0 ..< ?N}. \<bar>?diff n x - f' x0 n \<bar>)" ..
|
hoelzl@29740
|
709 |
also have "\<dots> < (\<Sum>n \<in> { 0 ..< ?N}. ?r)"
|
hoelzl@29740
|
710 |
proof (rule setsum_strict_mono)
|
hoelzl@29740
|
711 |
fix n assume "n \<in> { 0 ..< ?N}"
|
hoelzl@29740
|
712 |
have "\<bar> x \<bar> < S" using `\<bar> x \<bar> < S` .
|
hoelzl@29740
|
713 |
also have "S \<le> S'" using `S \<le> S'` .
|
hoelzl@29740
|
714 |
also have "S' \<le> ?s n" unfolding S'_def
|
hoelzl@29740
|
715 |
proof (rule Min_le_iff[THEN iffD2])
|
hoelzl@29740
|
716 |
have "?s n \<in> (?s ` {0..<?N}) \<and> ?s n \<le> ?s n" using `n \<in> { 0 ..< ?N}` by auto
|
hoelzl@29740
|
717 |
thus "\<exists> a \<in> (?s ` {0..<?N}). a \<le> ?s n" by blast
|
hoelzl@29740
|
718 |
qed auto
|
hoelzl@29740
|
719 |
finally have "\<bar> x \<bar> < ?s n" .
|
hoelzl@29740
|
720 |
|
hoelzl@29740
|
721 |
from DERIV_D[OF DERIV_f[where n=n], THEN LIM_D, OF `0 < ?r`, unfolded real_norm_def diff_0_right, unfolded some_eq_ex[symmetric], THEN conjunct2]
|
hoelzl@29740
|
722 |
have "\<forall>x. x \<noteq> 0 \<and> \<bar>x\<bar> < ?s n \<longrightarrow> \<bar>?diff n x - f' x0 n\<bar> < ?r" .
|
hoelzl@29740
|
723 |
with `x \<noteq> 0` and `\<bar>x\<bar> < ?s n`
|
hoelzl@29740
|
724 |
show "\<bar>?diff n x - f' x0 n\<bar> < ?r" by blast
|
hoelzl@29740
|
725 |
qed auto
|
hoelzl@29740
|
726 |
also have "\<dots> = of_nat (card {0 ..< ?N}) * ?r" by (rule setsum_constant)
|
hoelzl@29740
|
727 |
also have "\<dots> = real ?N * ?r" unfolding real_eq_of_nat by auto
|
hoelzl@29740
|
728 |
also have "\<dots> = r/3" by auto
|
hoelzl@29740
|
729 |
finally have "\<bar>\<Sum>n \<in> { 0 ..< ?N}. ?diff n x - f' x0 n \<bar> < r / 3" (is "?diff_part < r / 3") .
|
hoelzl@29740
|
730 |
|
hoelzl@29740
|
731 |
from suminf_diff[OF allf_summable[OF x_in_I] allf_summable[OF x0_in_I]]
|
hoelzl@29740
|
732 |
have "\<bar> (suminf (f (x0 + x)) - (suminf (f x0))) / x - suminf (f' x0) \<bar> =
|
hoelzl@29740
|
733 |
\<bar> \<Sum>n. ?diff n x - f' x0 n \<bar>" unfolding suminf_diff[OF div_smbl `summable (f' x0)`, symmetric] using suminf_divide[OF diff_smbl, symmetric] by auto
|
hoelzl@29740
|
734 |
also have "\<dots> \<le> ?diff_part + \<bar> (\<Sum>n. ?diff (n + ?N) x) - (\<Sum> n. f' x0 (n + ?N)) \<bar>" unfolding suminf_split_initial_segment[OF all_smbl, where k="?N"] unfolding suminf_diff[OF div_shft_smbl ign[OF `summable (f' x0)`]] by (rule abs_triangle_ineq)
|
hoelzl@29740
|
735 |
also have "\<dots> \<le> ?diff_part + ?L_part + ?f'_part" using abs_triangle_ineq4 by auto
|
hoelzl@29740
|
736 |
also have "\<dots> < r /3 + r/3 + r/3"
|
hoelzl@29740
|
737 |
using `?diff_part < r/3` `?L_part \<le> r/3` and `?f'_part < r/3` by auto
|
hoelzl@29740
|
738 |
finally have "\<bar> (suminf (f (x0 + x)) - (suminf (f x0))) / x - suminf (f' x0) \<bar> < r"
|
hoelzl@29740
|
739 |
by auto
|
hoelzl@29740
|
740 |
} thus "\<exists> s > 0. \<forall> x. x \<noteq> 0 \<and> norm (x - 0) < s \<longrightarrow>
|
hoelzl@29740
|
741 |
norm (((\<Sum>n. f (x0 + x) n) - (\<Sum>n. f x0 n)) / x - (\<Sum>n. f' x0 n)) < r" using `0 < S`
|
hoelzl@29740
|
742 |
unfolding real_norm_def diff_0_right by blast
|
hoelzl@29740
|
743 |
qed
|
hoelzl@29740
|
744 |
|
hoelzl@29740
|
745 |
lemma DERIV_power_series': fixes f :: "nat \<Rightarrow> real"
|
hoelzl@29740
|
746 |
assumes converges: "\<And> x. x \<in> {-R <..< R} \<Longrightarrow> summable (\<lambda> n. f n * real (Suc n) * x^n)"
|
hoelzl@29740
|
747 |
and x0_in_I: "x0 \<in> {-R <..< R}" and "0 < R"
|
hoelzl@29740
|
748 |
shows "DERIV (\<lambda> x. (\<Sum> n. f n * x^(Suc n))) x0 :> (\<Sum> n. f n * real (Suc n) * x0^n)"
|
hoelzl@29740
|
749 |
(is "DERIV (\<lambda> x. (suminf (?f x))) x0 :> (suminf (?f' x0))")
|
hoelzl@29740
|
750 |
proof -
|
hoelzl@29740
|
751 |
{ fix R' assume "0 < R'" and "R' < R" and "-R' < x0" and "x0 < R'"
|
hoelzl@29740
|
752 |
hence "x0 \<in> {-R' <..< R'}" and "R' \<in> {-R <..< R}" and "x0 \<in> {-R <..< R}" by auto
|
hoelzl@29740
|
753 |
have "DERIV (\<lambda> x. (suminf (?f x))) x0 :> (suminf (?f' x0))"
|
hoelzl@29740
|
754 |
proof (rule DERIV_series')
|
hoelzl@29740
|
755 |
show "summable (\<lambda> n. \<bar>f n * real (Suc n) * R'^n\<bar>)"
|
hoelzl@29740
|
756 |
proof -
|
hoelzl@29740
|
757 |
have "(R' + R) / 2 < R" and "0 < (R' + R) / 2" using `0 < R'` `0 < R` `R' < R` by auto
|
hoelzl@29740
|
758 |
hence in_Rball: "(R' + R) / 2 \<in> {-R <..< R}" using `R' < R` by auto
|
hoelzl@29740
|
759 |
have "norm R' < norm ((R' + R) / 2)" using `0 < R'` `0 < R` `R' < R` by auto
|
hoelzl@29740
|
760 |
from powser_insidea[OF converges[OF in_Rball] this] show ?thesis by auto
|
hoelzl@29740
|
761 |
qed
|
hoelzl@29740
|
762 |
{ fix n x y assume "x \<in> {-R' <..< R'}" and "y \<in> {-R' <..< R'}"
|
hoelzl@29740
|
763 |
show "\<bar>?f x n - ?f y n\<bar> \<le> \<bar>f n * real (Suc n) * R'^n\<bar> * \<bar>x-y\<bar>"
|
hoelzl@29740
|
764 |
proof -
|
hoelzl@29740
|
765 |
have "\<bar>f n * x ^ (Suc n) - f n * y ^ (Suc n)\<bar> = (\<bar>f n\<bar> * \<bar>x-y\<bar>) * \<bar>\<Sum>p = 0..<Suc n. x ^ p * y ^ (n - p)\<bar>"
|
hoelzl@29740
|
766 |
unfolding right_diff_distrib[symmetric] lemma_realpow_diff_sumr2 abs_mult by auto
|
hoelzl@29740
|
767 |
also have "\<dots> \<le> (\<bar>f n\<bar> * \<bar>x-y\<bar>) * (\<bar>real (Suc n)\<bar> * \<bar>R' ^ n\<bar>)"
|
hoelzl@29740
|
768 |
proof (rule mult_left_mono)
|
hoelzl@29740
|
769 |
have "\<bar>\<Sum>p = 0..<Suc n. x ^ p * y ^ (n - p)\<bar> \<le> (\<Sum>p = 0..<Suc n. \<bar>x ^ p * y ^ (n - p)\<bar>)" by (rule setsum_abs)
|
hoelzl@29740
|
770 |
also have "\<dots> \<le> (\<Sum>p = 0..<Suc n. R' ^ n)"
|
hoelzl@29740
|
771 |
proof (rule setsum_mono)
|
hoelzl@29740
|
772 |
fix p assume "p \<in> {0..<Suc n}" hence "p \<le> n" by auto
|
hoelzl@29740
|
773 |
{ fix n fix x :: real assume "x \<in> {-R'<..<R'}"
|
hoelzl@29740
|
774 |
hence "\<bar>x\<bar> \<le> R'" by auto
|
hoelzl@29740
|
775 |
hence "\<bar>x^n\<bar> \<le> R'^n" unfolding power_abs by (rule power_mono, auto)
|
hoelzl@29740
|
776 |
} from mult_mono[OF this[OF `x \<in> {-R'<..<R'}`, of p] this[OF `y \<in> {-R'<..<R'}`, of "n-p"]] `0 < R'`
|
hoelzl@29740
|
777 |
have "\<bar>x^p * y^(n-p)\<bar> \<le> R'^p * R'^(n-p)" unfolding abs_mult by auto
|
hoelzl@29740
|
778 |
thus "\<bar>x^p * y^(n-p)\<bar> \<le> R'^n" unfolding power_add[symmetric] using `p \<le> n` by auto
|
hoelzl@29740
|
779 |
qed
|
hoelzl@29740
|
780 |
also have "\<dots> = real (Suc n) * R' ^ n" unfolding setsum_constant card_atLeastLessThan real_of_nat_def by auto
|
hoelzl@29740
|
781 |
finally show "\<bar>\<Sum>p = 0..<Suc n. x ^ p * y ^ (n - p)\<bar> \<le> \<bar>real (Suc n)\<bar> * \<bar>R' ^ n\<bar>" unfolding abs_real_of_nat_cancel abs_of_nonneg[OF zero_le_power[OF less_imp_le[OF `0 < R'`]]] .
|
hoelzl@29740
|
782 |
show "0 \<le> \<bar>f n\<bar> * \<bar>x - y\<bar>" unfolding abs_mult[symmetric] by auto
|
hoelzl@29740
|
783 |
qed
|
hoelzl@29740
|
784 |
also have "\<dots> = \<bar>f n * real (Suc n) * R' ^ n\<bar> * \<bar>x - y\<bar>" unfolding abs_mult real_mult_assoc[symmetric] by algebra
|
hoelzl@29740
|
785 |
finally show ?thesis .
|
hoelzl@29740
|
786 |
qed }
|
hoelzl@29740
|
787 |
{ fix n
|
hoelzl@29740
|
788 |
from DERIV_pow[of "Suc n" x0, THEN DERIV_cmult[where c="f n"]]
|
hoelzl@29740
|
789 |
show "DERIV (\<lambda> x. ?f x n) x0 :> (?f' x0 n)" unfolding real_mult_assoc by auto }
|
hoelzl@29740
|
790 |
{ fix x assume "x \<in> {-R' <..< R'}" hence "R' \<in> {-R <..< R}" and "norm x < norm R'" using assms `R' < R` by auto
|
hoelzl@29740
|
791 |
have "summable (\<lambda> n. f n * x^n)"
|
hoelzl@29740
|
792 |
proof (rule summable_le2[THEN conjunct1, OF _ powser_insidea[OF converges[OF `R' \<in> {-R <..< R}`] `norm x < norm R'`]], rule allI)
|
hoelzl@29740
|
793 |
fix n
|
hoelzl@29740
|
794 |
have le: "\<bar>f n\<bar> * 1 \<le> \<bar>f n\<bar> * real (Suc n)" by (rule mult_left_mono, auto)
|
hoelzl@29740
|
795 |
show "\<bar>f n * x ^ n\<bar> \<le> norm (f n * real (Suc n) * x ^ n)" unfolding real_norm_def abs_mult
|
hoelzl@29740
|
796 |
by (rule mult_right_mono, auto simp add: le[unfolded mult_1_right])
|
hoelzl@29740
|
797 |
qed
|
hoelzl@29740
|
798 |
from this[THEN summable_mult2[where c=x], unfolded real_mult_assoc, unfolded real_mult_commute]
|
hoelzl@29740
|
799 |
show "summable (?f x)" by auto }
|
hoelzl@29740
|
800 |
show "summable (?f' x0)" using converges[OF `x0 \<in> {-R <..< R}`] .
|
hoelzl@29740
|
801 |
show "x0 \<in> {-R' <..< R'}" using `x0 \<in> {-R' <..< R'}` .
|
hoelzl@29740
|
802 |
qed
|
hoelzl@29740
|
803 |
} note for_subinterval = this
|
hoelzl@29740
|
804 |
let ?R = "(R + \<bar>x0\<bar>) / 2"
|
hoelzl@29740
|
805 |
have "\<bar>x0\<bar> < ?R" using assms by auto
|
hoelzl@29740
|
806 |
hence "- ?R < x0"
|
hoelzl@29740
|
807 |
proof (cases "x0 < 0")
|
hoelzl@29740
|
808 |
case True
|
hoelzl@29740
|
809 |
hence "- x0 < ?R" using `\<bar>x0\<bar> < ?R` by auto
|
hoelzl@29740
|
810 |
thus ?thesis unfolding neg_less_iff_less[symmetric, of "- x0"] by auto
|
hoelzl@29740
|
811 |
next
|
hoelzl@29740
|
812 |
case False
|
hoelzl@29740
|
813 |
have "- ?R < 0" using assms by auto
|
hoelzl@29740
|
814 |
also have "\<dots> \<le> x0" using False by auto
|
hoelzl@29740
|
815 |
finally show ?thesis .
|
hoelzl@29740
|
816 |
qed
|
hoelzl@29740
|
817 |
hence "0 < ?R" "?R < R" "- ?R < x0" and "x0 < ?R" using assms by auto
|
hoelzl@29740
|
818 |
from for_subinterval[OF this]
|
hoelzl@29740
|
819 |
show ?thesis .
|
hoelzl@29740
|
820 |
qed
|
chaieb@29695
|
821 |
|
huffman@29164
|
822 |
subsection {* Exponential Function *}
|
huffman@23043
|
823 |
|
huffman@23043
|
824 |
definition
|
haftmann@31017
|
825 |
exp :: "'a \<Rightarrow> 'a::{real_normed_field,banach}" where
|
haftmann@25062
|
826 |
"exp x = (\<Sum>n. x ^ n /\<^sub>R real (fact n))"
|
huffman@23043
|
827 |
|
huffman@23115
|
828 |
lemma summable_exp_generic:
|
haftmann@31017
|
829 |
fixes x :: "'a::{real_normed_algebra_1,banach}"
|
haftmann@25062
|
830 |
defines S_def: "S \<equiv> \<lambda>n. x ^ n /\<^sub>R real (fact n)"
|
huffman@23115
|
831 |
shows "summable S"
|
huffman@23115
|
832 |
proof -
|
haftmann@25062
|
833 |
have S_Suc: "\<And>n. S (Suc n) = (x * S n) /\<^sub>R real (Suc n)"
|
huffman@30269
|
834 |
unfolding S_def by (simp del: mult_Suc)
|
huffman@23115
|
835 |
obtain r :: real where r0: "0 < r" and r1: "r < 1"
|
huffman@23115
|
836 |
using dense [OF zero_less_one] by fast
|
huffman@23115
|
837 |
obtain N :: nat where N: "norm x < real N * r"
|
huffman@23115
|
838 |
using reals_Archimedean3 [OF r0] by fast
|
huffman@23115
|
839 |
from r1 show ?thesis
|
huffman@23115
|
840 |
proof (rule ratio_test [rule_format])
|
huffman@23115
|
841 |
fix n :: nat
|
huffman@23115
|
842 |
assume n: "N \<le> n"
|
huffman@23115
|
843 |
have "norm x \<le> real N * r"
|
huffman@23115
|
844 |
using N by (rule order_less_imp_le)
|
huffman@23115
|
845 |
also have "real N * r \<le> real (Suc n) * r"
|
huffman@23115
|
846 |
using r0 n by (simp add: mult_right_mono)
|
huffman@23115
|
847 |
finally have "norm x * norm (S n) \<le> real (Suc n) * r * norm (S n)"
|
huffman@23115
|
848 |
using norm_ge_zero by (rule mult_right_mono)
|
huffman@23115
|
849 |
hence "norm (x * S n) \<le> real (Suc n) * r * norm (S n)"
|
huffman@23115
|
850 |
by (rule order_trans [OF norm_mult_ineq])
|
huffman@23115
|
851 |
hence "norm (x * S n) / real (Suc n) \<le> r * norm (S n)"
|
huffman@23115
|
852 |
by (simp add: pos_divide_le_eq mult_ac)
|
huffman@23115
|
853 |
thus "norm (S (Suc n)) \<le> r * norm (S n)"
|
huffman@23115
|
854 |
by (simp add: S_Suc norm_scaleR inverse_eq_divide)
|
huffman@23115
|
855 |
qed
|
huffman@23115
|
856 |
qed
|
huffman@23115
|
857 |
|
huffman@23115
|
858 |
lemma summable_norm_exp:
|
haftmann@31017
|
859 |
fixes x :: "'a::{real_normed_algebra_1,banach}"
|
haftmann@25062
|
860 |
shows "summable (\<lambda>n. norm (x ^ n /\<^sub>R real (fact n)))"
|
huffman@23115
|
861 |
proof (rule summable_norm_comparison_test [OF exI, rule_format])
|
haftmann@25062
|
862 |
show "summable (\<lambda>n. norm x ^ n /\<^sub>R real (fact n))"
|
huffman@23115
|
863 |
by (rule summable_exp_generic)
|
huffman@23115
|
864 |
next
|
haftmann@25062
|
865 |
fix n show "norm (x ^ n /\<^sub>R real (fact n)) \<le> norm x ^ n /\<^sub>R real (fact n)"
|
huffman@23115
|
866 |
by (simp add: norm_scaleR norm_power_ineq)
|
huffman@23115
|
867 |
qed
|
huffman@23115
|
868 |
|
huffman@23043
|
869 |
lemma summable_exp: "summable (%n. inverse (real (fact n)) * x ^ n)"
|
huffman@23115
|
870 |
by (insert summable_exp_generic [where x=x], simp)
|
huffman@23043
|
871 |
|
haftmann@25062
|
872 |
lemma exp_converges: "(\<lambda>n. x ^ n /\<^sub>R real (fact n)) sums exp x"
|
huffman@23115
|
873 |
unfolding exp_def by (rule summable_exp_generic [THEN summable_sums])
|
huffman@23043
|
874 |
|
huffman@23043
|
875 |
|
paulson@15077
|
876 |
lemma exp_fdiffs:
|
paulson@15077
|
877 |
"diffs (%n. inverse(real (fact n))) = (%n. inverse(real (fact n)))"
|
huffman@23431
|
878 |
by (simp add: diffs_def mult_assoc [symmetric] real_of_nat_def of_nat_mult
|
huffman@23082
|
879 |
del: mult_Suc of_nat_Suc)
|
paulson@15077
|
880 |
|
huffman@23115
|
881 |
lemma diffs_of_real: "diffs (\<lambda>n. of_real (f n)) = (\<lambda>n. of_real (diffs f n))"
|
huffman@23115
|
882 |
by (simp add: diffs_def)
|
huffman@23115
|
883 |
|
haftmann@25062
|
884 |
lemma lemma_exp_ext: "exp = (\<lambda>x. \<Sum>n. x ^ n /\<^sub>R real (fact n))"
|
paulson@15077
|
885 |
by (auto intro!: ext simp add: exp_def)
|
paulson@15077
|
886 |
|
paulson@15077
|
887 |
lemma DERIV_exp [simp]: "DERIV exp x :> exp(x)"
|
paulson@15229
|
888 |
apply (simp add: exp_def)
|
paulson@15077
|
889 |
apply (subst lemma_exp_ext)
|
huffman@23115
|
890 |
apply (subgoal_tac "DERIV (\<lambda>u. \<Sum>n. of_real (inverse (real (fact n))) * u ^ n) x :> (\<Sum>n. diffs (\<lambda>n. of_real (inverse (real (fact n)))) n * x ^ n)")
|
huffman@23115
|
891 |
apply (rule_tac [2] K = "of_real (1 + norm x)" in termdiffs)
|
huffman@23115
|
892 |
apply (simp_all only: diffs_of_real scaleR_conv_of_real exp_fdiffs)
|
huffman@23115
|
893 |
apply (rule exp_converges [THEN sums_summable, unfolded scaleR_conv_of_real])+
|
huffman@23115
|
894 |
apply (simp del: of_real_add)
|
paulson@15077
|
895 |
done
|
paulson@15077
|
896 |
|
huffman@23045
|
897 |
lemma isCont_exp [simp]: "isCont exp x"
|
huffman@23045
|
898 |
by (rule DERIV_exp [THEN DERIV_isCont])
|
huffman@23045
|
899 |
|
huffman@23045
|
900 |
|
huffman@29167
|
901 |
subsubsection {* Properties of the Exponential Function *}
|
paulson@15077
|
902 |
|
huffman@23278
|
903 |
lemma powser_zero:
|
haftmann@31017
|
904 |
fixes f :: "nat \<Rightarrow> 'a::{real_normed_algebra_1}"
|
huffman@23278
|
905 |
shows "(\<Sum>n. f n * 0 ^ n) = f 0"
|
huffman@23278
|
906 |
proof -
|
huffman@23278
|
907 |
have "(\<Sum>n = 0..<1. f n * 0 ^ n) = (\<Sum>n. f n * 0 ^ n)"
|
huffman@23278
|
908 |
by (rule sums_unique [OF series_zero], simp add: power_0_left)
|
huffman@30019
|
909 |
thus ?thesis unfolding One_nat_def by simp
|
huffman@23278
|
910 |
qed
|
huffman@23278
|
911 |
|
paulson@15077
|
912 |
lemma exp_zero [simp]: "exp 0 = 1"
|
huffman@23278
|
913 |
unfolding exp_def by (simp add: scaleR_conv_of_real powser_zero)
|
paulson@15077
|
914 |
|
huffman@23115
|
915 |
lemma setsum_cl_ivl_Suc2:
|
huffman@23115
|
916 |
"(\<Sum>i=m..Suc n. f i) = (if Suc n < m then 0 else f m + (\<Sum>i=m..n. f (Suc i)))"
|
nipkow@28069
|
917 |
by (simp add: setsum_head_Suc setsum_shift_bounds_cl_Suc_ivl
|
huffman@23115
|
918 |
del: setsum_cl_ivl_Suc)
|
huffman@23115
|
919 |
|
huffman@23115
|
920 |
lemma exp_series_add:
|
haftmann@31017
|
921 |
fixes x y :: "'a::{real_field}"
|
haftmann@25062
|
922 |
defines S_def: "S \<equiv> \<lambda>x n. x ^ n /\<^sub>R real (fact n)"
|
huffman@23115
|
923 |
shows "S (x + y) n = (\<Sum>i=0..n. S x i * S y (n - i))"
|
huffman@23115
|
924 |
proof (induct n)
|
huffman@23115
|
925 |
case 0
|
huffman@23115
|
926 |
show ?case
|
huffman@23115
|
927 |
unfolding S_def by simp
|
huffman@23115
|
928 |
next
|
huffman@23115
|
929 |
case (Suc n)
|
haftmann@25062
|
930 |
have S_Suc: "\<And>x n. S x (Suc n) = (x * S x n) /\<^sub>R real (Suc n)"
|
huffman@30269
|
931 |
unfolding S_def by (simp del: mult_Suc)
|
haftmann@25062
|
932 |
hence times_S: "\<And>x n. x * S x n = real (Suc n) *\<^sub>R S x (Suc n)"
|
huffman@23115
|
933 |
by simp
|
huffman@23115
|
934 |
|
haftmann@25062
|
935 |
have "real (Suc n) *\<^sub>R S (x + y) (Suc n) = (x + y) * S (x + y) n"
|
huffman@23115
|
936 |
by (simp only: times_S)
|
huffman@23115
|
937 |
also have "\<dots> = (x + y) * (\<Sum>i=0..n. S x i * S y (n-i))"
|
huffman@23115
|
938 |
by (simp only: Suc)
|
huffman@23115
|
939 |
also have "\<dots> = x * (\<Sum>i=0..n. S x i * S y (n-i))
|
huffman@23115
|
940 |
+ y * (\<Sum>i=0..n. S x i * S y (n-i))"
|
huffman@23115
|
941 |
by (rule left_distrib)
|
huffman@23115
|
942 |
also have "\<dots> = (\<Sum>i=0..n. (x * S x i) * S y (n-i))
|
huffman@23115
|
943 |
+ (\<Sum>i=0..n. S x i * (y * S y (n-i)))"
|
huffman@23115
|
944 |
by (simp only: setsum_right_distrib mult_ac)
|
haftmann@25062
|
945 |
also have "\<dots> = (\<Sum>i=0..n. real (Suc i) *\<^sub>R (S x (Suc i) * S y (n-i)))
|
haftmann@25062
|
946 |
+ (\<Sum>i=0..n. real (Suc n-i) *\<^sub>R (S x i * S y (Suc n-i)))"
|
huffman@23115
|
947 |
by (simp add: times_S Suc_diff_le)
|
haftmann@25062
|
948 |
also have "(\<Sum>i=0..n. real (Suc i) *\<^sub>R (S x (Suc i) * S y (n-i))) =
|
haftmann@25062
|
949 |
(\<Sum>i=0..Suc n. real i *\<^sub>R (S x i * S y (Suc n-i)))"
|
huffman@23115
|
950 |
by (subst setsum_cl_ivl_Suc2, simp)
|
haftmann@25062
|
951 |
also have "(\<Sum>i=0..n. real (Suc n-i) *\<^sub>R (S x i * S y (Suc n-i))) =
|
haftmann@25062
|
952 |
(\<Sum>i=0..Suc n. real (Suc n-i) *\<^sub>R (S x i * S y (Suc n-i)))"
|
huffman@23115
|
953 |
by (subst setsum_cl_ivl_Suc, simp)
|
haftmann@25062
|
954 |
also have "(\<Sum>i=0..Suc n. real i *\<^sub>R (S x i * S y (Suc n-i))) +
|
haftmann@25062
|
955 |
(\<Sum>i=0..Suc n. real (Suc n-i) *\<^sub>R (S x i * S y (Suc n-i))) =
|
haftmann@25062
|
956 |
(\<Sum>i=0..Suc n. real (Suc n) *\<^sub>R (S x i * S y (Suc n-i)))"
|
huffman@23115
|
957 |
by (simp only: setsum_addf [symmetric] scaleR_left_distrib [symmetric]
|
huffman@23115
|
958 |
real_of_nat_add [symmetric], simp)
|
haftmann@25062
|
959 |
also have "\<dots> = real (Suc n) *\<^sub>R (\<Sum>i=0..Suc n. S x i * S y (Suc n-i))"
|
huffman@23127
|
960 |
by (simp only: scaleR_right.setsum)
|
huffman@23115
|
961 |
finally show
|
huffman@23115
|
962 |
"S (x + y) (Suc n) = (\<Sum>i=0..Suc n. S x i * S y (Suc n - i))"
|
huffman@23115
|
963 |
by (simp add: scaleR_cancel_left del: setsum_cl_ivl_Suc)
|
huffman@23115
|
964 |
qed
|
huffman@23115
|
965 |
|
huffman@23115
|
966 |
lemma exp_add: "exp (x + y) = exp x * exp y"
|
huffman@23115
|
967 |
unfolding exp_def
|
huffman@23115
|
968 |
by (simp only: Cauchy_product summable_norm_exp exp_series_add)
|
huffman@23115
|
969 |
|
huffman@29170
|
970 |
lemma mult_exp_exp: "exp x * exp y = exp (x + y)"
|
huffman@29170
|
971 |
by (rule exp_add [symmetric])
|
huffman@29170
|
972 |
|
huffman@23241
|
973 |
lemma exp_of_real: "exp (of_real x) = of_real (exp x)"
|
huffman@23241
|
974 |
unfolding exp_def
|
huffman@23241
|
975 |
apply (subst of_real.suminf)
|
huffman@23241
|
976 |
apply (rule summable_exp_generic)
|
huffman@23241
|
977 |
apply (simp add: scaleR_conv_of_real)
|
huffman@23241
|
978 |
done
|
huffman@23241
|
979 |
|
huffman@29170
|
980 |
lemma exp_not_eq_zero [simp]: "exp x \<noteq> 0"
|
huffman@29170
|
981 |
proof
|
huffman@29170
|
982 |
have "exp x * exp (- x) = 1" by (simp add: mult_exp_exp)
|
huffman@29170
|
983 |
also assume "exp x = 0"
|
huffman@29170
|
984 |
finally show "False" by simp
|
paulson@15077
|
985 |
qed
|
paulson@15077
|
986 |
|
huffman@29170
|
987 |
lemma exp_minus: "exp (- x) = inverse (exp x)"
|
huffman@29170
|
988 |
by (rule inverse_unique [symmetric], simp add: mult_exp_exp)
|
paulson@15077
|
989 |
|
huffman@29170
|
990 |
lemma exp_diff: "exp (x - y) = exp x / exp y"
|
huffman@29170
|
991 |
unfolding diff_minus divide_inverse
|
huffman@29170
|
992 |
by (simp add: exp_add exp_minus)
|
paulson@15077
|
993 |
|
huffman@29167
|
994 |
|
huffman@29167
|
995 |
subsubsection {* Properties of the Exponential Function on Reals *}
|
huffman@29167
|
996 |
|
huffman@29170
|
997 |
text {* Comparisons of @{term "exp x"} with zero. *}
|
huffman@29167
|
998 |
|
huffman@29167
|
999 |
text{*Proof: because every exponential can be seen as a square.*}
|
huffman@29167
|
1000 |
lemma exp_ge_zero [simp]: "0 \<le> exp (x::real)"
|
huffman@29167
|
1001 |
proof -
|
huffman@29167
|
1002 |
have "0 \<le> exp (x/2) * exp (x/2)" by simp
|
huffman@29167
|
1003 |
thus ?thesis by (simp add: exp_add [symmetric])
|
huffman@29167
|
1004 |
qed
|
huffman@29167
|
1005 |
|
huffman@23115
|
1006 |
lemma exp_gt_zero [simp]: "0 < exp (x::real)"
|
paulson@15077
|
1007 |
by (simp add: order_less_le)
|
paulson@15077
|
1008 |
|
huffman@29170
|
1009 |
lemma not_exp_less_zero [simp]: "\<not> exp (x::real) < 0"
|
huffman@29170
|
1010 |
by (simp add: not_less)
|
huffman@29170
|
1011 |
|
huffman@29170
|
1012 |
lemma not_exp_le_zero [simp]: "\<not> exp (x::real) \<le> 0"
|
huffman@29170
|
1013 |
by (simp add: not_le)
|
paulson@15077
|
1014 |
|
huffman@23115
|
1015 |
lemma abs_exp_cancel [simp]: "\<bar>exp x::real\<bar> = exp x"
|
huffman@29165
|
1016 |
by simp
|
paulson@15077
|
1017 |
|
paulson@15077
|
1018 |
lemma exp_real_of_nat_mult: "exp(real n * x) = exp(x) ^ n"
|
paulson@15251
|
1019 |
apply (induct "n")
|
paulson@15077
|
1020 |
apply (auto simp add: real_of_nat_Suc right_distrib exp_add mult_commute)
|
paulson@15077
|
1021 |
done
|
paulson@15077
|
1022 |
|
huffman@29170
|
1023 |
text {* Strict monotonicity of exponential. *}
|
huffman@29170
|
1024 |
|
huffman@29170
|
1025 |
lemma exp_ge_add_one_self_aux: "0 \<le> (x::real) ==> (1 + x) \<le> exp(x)"
|
huffman@29170
|
1026 |
apply (drule order_le_imp_less_or_eq, auto)
|
huffman@29170
|
1027 |
apply (simp add: exp_def)
|
huffman@29170
|
1028 |
apply (rule real_le_trans)
|
huffman@29170
|
1029 |
apply (rule_tac [2] n = 2 and f = "(%n. inverse (real (fact n)) * x ^ n)" in series_pos_le)
|
huffman@29170
|
1030 |
apply (auto intro: summable_exp simp add: numeral_2_eq_2 zero_le_mult_iff)
|
huffman@29170
|
1031 |
done
|
huffman@29170
|
1032 |
|
huffman@29170
|
1033 |
lemma exp_gt_one: "0 < (x::real) \<Longrightarrow> 1 < exp x"
|
huffman@29170
|
1034 |
proof -
|
huffman@29170
|
1035 |
assume x: "0 < x"
|
huffman@29170
|
1036 |
hence "1 < 1 + x" by simp
|
huffman@29170
|
1037 |
also from x have "1 + x \<le> exp x"
|
huffman@29170
|
1038 |
by (simp add: exp_ge_add_one_self_aux)
|
huffman@29170
|
1039 |
finally show ?thesis .
|
huffman@29170
|
1040 |
qed
|
huffman@29170
|
1041 |
|
paulson@15077
|
1042 |
lemma exp_less_mono:
|
huffman@23115
|
1043 |
fixes x y :: real
|
huffman@29165
|
1044 |
assumes "x < y" shows "exp x < exp y"
|
paulson@15077
|
1045 |
proof -
|
huffman@29165
|
1046 |
from `x < y` have "0 < y - x" by simp
|
huffman@29165
|
1047 |
hence "1 < exp (y - x)" by (rule exp_gt_one)
|
huffman@29165
|
1048 |
hence "1 < exp y / exp x" by (simp only: exp_diff)
|
huffman@29165
|
1049 |
thus "exp x < exp y" by simp
|
paulson@15077
|
1050 |
qed
|
paulson@15077
|
1051 |
|
huffman@23115
|
1052 |
lemma exp_less_cancel: "exp (x::real) < exp y ==> x < y"
|
huffman@29170
|
1053 |
apply (simp add: linorder_not_le [symmetric])
|
huffman@29170
|
1054 |
apply (auto simp add: order_le_less exp_less_mono)
|
paulson@15077
|
1055 |
done
|
paulson@15077
|
1056 |
|
huffman@29170
|
1057 |
lemma exp_less_cancel_iff [iff]: "exp (x::real) < exp y \<longleftrightarrow> x < y"
|
paulson@15077
|
1058 |
by (auto intro: exp_less_mono exp_less_cancel)
|
paulson@15077
|
1059 |
|
huffman@29170
|
1060 |
lemma exp_le_cancel_iff [iff]: "exp (x::real) \<le> exp y \<longleftrightarrow> x \<le> y"
|
paulson@15077
|
1061 |
by (auto simp add: linorder_not_less [symmetric])
|
paulson@15077
|
1062 |
|
huffman@29170
|
1063 |
lemma exp_inj_iff [iff]: "exp (x::real) = exp y \<longleftrightarrow> x = y"
|
paulson@15077
|
1064 |
by (simp add: order_eq_iff)
|
paulson@15077
|
1065 |
|
huffman@29170
|
1066 |
text {* Comparisons of @{term "exp x"} with one. *}
|
huffman@29170
|
1067 |
|
huffman@29170
|
1068 |
lemma one_less_exp_iff [simp]: "1 < exp (x::real) \<longleftrightarrow> 0 < x"
|
huffman@29170
|
1069 |
using exp_less_cancel_iff [where x=0 and y=x] by simp
|
huffman@29170
|
1070 |
|
huffman@29170
|
1071 |
lemma exp_less_one_iff [simp]: "exp (x::real) < 1 \<longleftrightarrow> x < 0"
|
huffman@29170
|
1072 |
using exp_less_cancel_iff [where x=x and y=0] by simp
|
huffman@29170
|
1073 |
|
huffman@29170
|
1074 |
lemma one_le_exp_iff [simp]: "1 \<le> exp (x::real) \<longleftrightarrow> 0 \<le> x"
|
huffman@29170
|
1075 |
using exp_le_cancel_iff [where x=0 and y=x] by simp
|
huffman@29170
|
1076 |
|
huffman@29170
|
1077 |
lemma exp_le_one_iff [simp]: "exp (x::real) \<le> 1 \<longleftrightarrow> x \<le> 0"
|
huffman@29170
|
1078 |
using exp_le_cancel_iff [where x=x and y=0] by simp
|
huffman@29170
|
1079 |
|
huffman@29170
|
1080 |
lemma exp_eq_one_iff [simp]: "exp (x::real) = 1 \<longleftrightarrow> x = 0"
|
huffman@29170
|
1081 |
using exp_inj_iff [where x=x and y=0] by simp
|
huffman@29170
|
1082 |
|
huffman@23115
|
1083 |
lemma lemma_exp_total: "1 \<le> y ==> \<exists>x. 0 \<le> x & x \<le> y - 1 & exp(x::real) = y"
|
paulson@15077
|
1084 |
apply (rule IVT)
|
huffman@23045
|
1085 |
apply (auto intro: isCont_exp simp add: le_diff_eq)
|
paulson@15077
|
1086 |
apply (subgoal_tac "1 + (y - 1) \<le> exp (y - 1)")
|
huffman@29165
|
1087 |
apply simp
|
avigad@17014
|
1088 |
apply (rule exp_ge_add_one_self_aux, simp)
|
paulson@15077
|
1089 |
done
|
paulson@15077
|
1090 |
|
huffman@23115
|
1091 |
lemma exp_total: "0 < (y::real) ==> \<exists>x. exp x = y"
|
paulson@15077
|
1092 |
apply (rule_tac x = 1 and y = y in linorder_cases)
|
paulson@15077
|
1093 |
apply (drule order_less_imp_le [THEN lemma_exp_total])
|
paulson@15077
|
1094 |
apply (rule_tac [2] x = 0 in exI)
|
paulson@15077
|
1095 |
apply (frule_tac [3] real_inverse_gt_one)
|
paulson@15077
|
1096 |
apply (drule_tac [4] order_less_imp_le [THEN lemma_exp_total], auto)
|
paulson@15077
|
1097 |
apply (rule_tac x = "-x" in exI)
|
paulson@15077
|
1098 |
apply (simp add: exp_minus)
|
paulson@15077
|
1099 |
done
|
paulson@15077
|
1100 |
|
paulson@15077
|
1101 |
|
huffman@29164
|
1102 |
subsection {* Natural Logarithm *}
|
paulson@15077
|
1103 |
|
huffman@23043
|
1104 |
definition
|
huffman@23043
|
1105 |
ln :: "real => real" where
|
huffman@23043
|
1106 |
"ln x = (THE u. exp u = x)"
|
huffman@23043
|
1107 |
|
huffman@23043
|
1108 |
lemma ln_exp [simp]: "ln (exp x) = x"
|
paulson@15077
|
1109 |
by (simp add: ln_def)
|
paulson@15077
|
1110 |
|
huffman@22654
|
1111 |
lemma exp_ln [simp]: "0 < x \<Longrightarrow> exp (ln x) = x"
|
huffman@22654
|
1112 |
by (auto dest: exp_total)
|
huffman@22654
|
1113 |
|
huffman@29171
|
1114 |
lemma exp_ln_iff [simp]: "exp (ln x) = x \<longleftrightarrow> 0 < x"
|
huffman@29171
|
1115 |
apply (rule iffI)
|
huffman@29171
|
1116 |
apply (erule subst, rule exp_gt_zero)
|
huffman@29171
|
1117 |
apply (erule exp_ln)
|
paulson@15077
|
1118 |
done
|
paulson@15077
|
1119 |
|
huffman@29171
|
1120 |
lemma ln_unique: "exp y = x \<Longrightarrow> ln x = y"
|
huffman@29171
|
1121 |
by (erule subst, rule ln_exp)
|
huffman@29171
|
1122 |
|
huffman@29171
|
1123 |
lemma ln_one [simp]: "ln 1 = 0"
|
huffman@29171
|
1124 |
by (rule ln_unique, simp)
|
huffman@29171
|
1125 |
|
huffman@29171
|
1126 |
lemma ln_mult: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln (x * y) = ln x + ln y"
|
huffman@29171
|
1127 |
by (rule ln_unique, simp add: exp_add)
|
huffman@29171
|
1128 |
|
huffman@29171
|
1129 |
lemma ln_inverse: "0 < x \<Longrightarrow> ln (inverse x) = - ln x"
|
huffman@29171
|
1130 |
by (rule ln_unique, simp add: exp_minus)
|
huffman@29171
|
1131 |
|
huffman@29171
|
1132 |
lemma ln_div: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln (x / y) = ln x - ln y"
|
huffman@29171
|
1133 |
by (rule ln_unique, simp add: exp_diff)
|
huffman@29171
|
1134 |
|
huffman@29171
|
1135 |
lemma ln_realpow: "0 < x \<Longrightarrow> ln (x ^ n) = real n * ln x"
|
huffman@29171
|
1136 |
by (rule ln_unique, simp add: exp_real_of_nat_mult)
|
huffman@29171
|
1137 |
|
huffman@29171
|
1138 |
lemma ln_less_cancel_iff [simp]: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln x < ln y \<longleftrightarrow> x < y"
|
huffman@29171
|
1139 |
by (subst exp_less_cancel_iff [symmetric], simp)
|
huffman@29171
|
1140 |
|
huffman@29171
|
1141 |
lemma ln_le_cancel_iff [simp]: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln x \<le> ln y \<longleftrightarrow> x \<le> y"
|
huffman@29171
|
1142 |
by (simp add: linorder_not_less [symmetric])
|
huffman@29171
|
1143 |
|
huffman@29171
|
1144 |
lemma ln_inj_iff [simp]: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln x = ln y \<longleftrightarrow> x = y"
|
huffman@29171
|
1145 |
by (simp add: order_eq_iff)
|
huffman@29171
|
1146 |
|
huffman@29171
|
1147 |
lemma ln_add_one_self_le_self [simp]: "0 \<le> x \<Longrightarrow> ln (1 + x) \<le> x"
|
huffman@29171
|
1148 |
apply (rule exp_le_cancel_iff [THEN iffD1])
|
huffman@29171
|
1149 |
apply (simp add: exp_ge_add_one_self_aux)
|
paulson@15077
|
1150 |
done
|
paulson@15077
|
1151 |
|
huffman@29171
|
1152 |
lemma ln_less_self [simp]: "0 < x \<Longrightarrow> ln x < x"
|
huffman@29171
|
1153 |
by (rule order_less_le_trans [where y="ln (1 + x)"]) simp_all
|
paulson@15077
|
1154 |
|
paulson@15234
|
1155 |
lemma ln_ge_zero [simp]:
|
paulson@15077
|
1156 |
assumes x: "1 \<le> x" shows "0 \<le> ln x"
|
paulson@15077
|
1157 |
proof -
|
paulson@15077
|
1158 |
have "0 < x" using x by arith
|
paulson@15077
|
1159 |
hence "exp 0 \<le> exp (ln x)"
|
huffman@22915
|
1160 |
by (simp add: x)
|
paulson@15077
|
1161 |
thus ?thesis by (simp only: exp_le_cancel_iff)
|
paulson@15077
|
1162 |
qed
|
paulson@15077
|
1163 |
|
paulson@15077
|
1164 |
lemma ln_ge_zero_imp_ge_one:
|
paulson@15077
|
1165 |
assumes ln: "0 \<le> ln x"
|
paulson@15077
|
1166 |
and x: "0 < x"
|
paulson@15077
|
1167 |
shows "1 \<le> x"
|
paulson@15077
|
1168 |
proof -
|
paulson@15077
|
1169 |
from ln have "ln 1 \<le> ln x" by simp
|
paulson@15077
|
1170 |
thus ?thesis by (simp add: x del: ln_one)
|
paulson@15077
|
1171 |
qed
|
paulson@15077
|
1172 |
|
paulson@15077
|
1173 |
lemma ln_ge_zero_iff [simp]: "0 < x ==> (0 \<le> ln x) = (1 \<le> x)"
|
paulson@15077
|
1174 |
by (blast intro: ln_ge_zero ln_ge_zero_imp_ge_one)
|
paulson@15077
|
1175 |
|
paulson@15234
|
1176 |
lemma ln_less_zero_iff [simp]: "0 < x ==> (ln x < 0) = (x < 1)"
|
paulson@15234
|
1177 |
by (insert ln_ge_zero_iff [of x], arith)
|
paulson@15234
|
1178 |
|
paulson@15077
|
1179 |
lemma ln_gt_zero:
|
paulson@15077
|
1180 |
assumes x: "1 < x" shows "0 < ln x"
|
paulson@15077
|
1181 |
proof -
|
paulson@15077
|
1182 |
have "0 < x" using x by arith
|
huffman@22915
|
1183 |
hence "exp 0 < exp (ln x)" by (simp add: x)
|
paulson@15077
|
1184 |
thus ?thesis by (simp only: exp_less_cancel_iff)
|
paulson@15077
|
1185 |
qed
|
paulson@15077
|
1186 |
|
paulson@15077
|
1187 |
lemma ln_gt_zero_imp_gt_one:
|
paulson@15077
|
1188 |
assumes ln: "0 < ln x"
|
paulson@15077
|
1189 |
and x: "0 < x"
|
paulson@15077
|
1190 |
shows "1 < x"
|
paulson@15077
|
1191 |
proof -
|
paulson@15077
|
1192 |
from ln have "ln 1 < ln x" by simp
|
paulson@15077
|
1193 |
thus ?thesis by (simp add: x del: ln_one)
|
paulson@15077
|
1194 |
qed
|
paulson@15077
|
1195 |
|
paulson@15077
|
1196 |
lemma ln_gt_zero_iff [simp]: "0 < x ==> (0 < ln x) = (1 < x)"
|
paulson@15077
|
1197 |
by (blast intro: ln_gt_zero ln_gt_zero_imp_gt_one)
|
paulson@15077
|
1198 |
|
paulson@15234
|
1199 |
lemma ln_eq_zero_iff [simp]: "0 < x ==> (ln x = 0) = (x = 1)"
|
paulson@15234
|
1200 |
by (insert ln_less_zero_iff [of x] ln_gt_zero_iff [of x], arith)
|
paulson@15077
|
1201 |
|
paulson@15077
|
1202 |
lemma ln_less_zero: "[| 0 < x; x < 1 |] ==> ln x < 0"
|
paulson@15234
|
1203 |
by simp
|
paulson@15077
|
1204 |
|
paulson@15077
|
1205 |
lemma exp_ln_eq: "exp u = x ==> ln x = u"
|
paulson@15077
|
1206 |
by auto
|
paulson@15077
|
1207 |
|
huffman@23045
|
1208 |
lemma isCont_ln: "0 < x \<Longrightarrow> isCont ln x"
|
huffman@23045
|
1209 |
apply (subgoal_tac "isCont ln (exp (ln x))", simp)
|
huffman@23045
|
1210 |
apply (rule isCont_inverse_function [where f=exp], simp_all)
|
huffman@23045
|
1211 |
done
|
huffman@23045
|
1212 |
|
huffman@23045
|
1213 |
lemma DERIV_ln: "0 < x \<Longrightarrow> DERIV ln x :> inverse x"
|
huffman@23045
|
1214 |
apply (rule DERIV_inverse_function [where f=exp and a=0 and b="x+1"])
|
huffman@23045
|
1215 |
apply (erule lemma_DERIV_subst [OF DERIV_exp exp_ln])
|
huffman@23045
|
1216 |
apply (simp_all add: abs_if isCont_ln)
|
huffman@23045
|
1217 |
done
|
huffman@23045
|
1218 |
|
hoelzl@29740
|
1219 |
lemma ln_series: assumes "0 < x" and "x < 2"
|
hoelzl@29740
|
1220 |
shows "ln x = (\<Sum> n. (-1)^n * (1 / real (n + 1)) * (x - 1)^(Suc n))" (is "ln x = suminf (?f (x - 1))")
|
hoelzl@29740
|
1221 |
proof -
|
hoelzl@29740
|
1222 |
let "?f' x n" = "(-1)^n * (x - 1)^n"
|
hoelzl@29740
|
1223 |
|
hoelzl@29740
|
1224 |
have "ln x - suminf (?f (x - 1)) = ln 1 - suminf (?f (1 - 1))"
|
hoelzl@29740
|
1225 |
proof (rule DERIV_isconst3[where x=x])
|
hoelzl@29740
|
1226 |
fix x :: real assume "x \<in> {0 <..< 2}" hence "0 < x" and "x < 2" by auto
|
hoelzl@29740
|
1227 |
have "norm (1 - x) < 1" using `0 < x` and `x < 2` by auto
|
hoelzl@29740
|
1228 |
have "1 / x = 1 / (1 - (1 - x))" by auto
|
hoelzl@29740
|
1229 |
also have "\<dots> = (\<Sum> n. (1 - x)^n)" using geometric_sums[OF `norm (1 - x) < 1`] by (rule sums_unique)
|
hoelzl@29740
|
1230 |
also have "\<dots> = suminf (?f' x)" unfolding power_mult_distrib[symmetric] by (rule arg_cong[where f=suminf], rule arg_cong[where f="op ^"], auto)
|
hoelzl@29740
|
1231 |
finally have "DERIV ln x :> suminf (?f' x)" using DERIV_ln[OF `0 < x`] unfolding real_divide_def by auto
|
hoelzl@29740
|
1232 |
moreover
|
hoelzl@29740
|
1233 |
have repos: "\<And> h x :: real. h - 1 + x = h + x - 1" by auto
|
hoelzl@29740
|
1234 |
have "DERIV (\<lambda>x. suminf (?f x)) (x - 1) :> (\<Sum>n. (-1)^n * (1 / real (n + 1)) * real (Suc n) * (x - 1) ^ n)"
|
hoelzl@29740
|
1235 |
proof (rule DERIV_power_series')
|
hoelzl@29740
|
1236 |
show "x - 1 \<in> {- 1<..<1}" and "(0 :: real) < 1" using `0 < x` `x < 2` by auto
|
hoelzl@29740
|
1237 |
{ fix x :: real assume "x \<in> {- 1<..<1}" hence "norm (-x) < 1" by auto
|
hoelzl@29740
|
1238 |
show "summable (\<lambda>n. -1 ^ n * (1 / real (n + 1)) * real (Suc n) * x ^ n)"
|
huffman@30019
|
1239 |
unfolding One_nat_def
|
hoelzl@29740
|
1240 |
by (auto simp del: power_mult_distrib simp add: power_mult_distrib[symmetric] summable_geometric[OF `norm (-x) < 1`])
|
hoelzl@29740
|
1241 |
}
|
hoelzl@29740
|
1242 |
qed
|
huffman@30019
|
1243 |
hence "DERIV (\<lambda>x. suminf (?f x)) (x - 1) :> suminf (?f' x)" unfolding One_nat_def by auto
|
hoelzl@29740
|
1244 |
hence "DERIV (\<lambda>x. suminf (?f (x - 1))) x :> suminf (?f' x)" unfolding DERIV_iff repos .
|
hoelzl@29740
|
1245 |
ultimately have "DERIV (\<lambda>x. ln x - suminf (?f (x - 1))) x :> (suminf (?f' x) - suminf (?f' x))"
|
hoelzl@29740
|
1246 |
by (rule DERIV_diff)
|
hoelzl@29740
|
1247 |
thus "DERIV (\<lambda>x. ln x - suminf (?f (x - 1))) x :> 0" by auto
|
hoelzl@29740
|
1248 |
qed (auto simp add: assms)
|
hoelzl@29740
|
1249 |
thus ?thesis by (auto simp add: suminf_zero)
|
hoelzl@29740
|
1250 |
qed
|
paulson@15077
|
1251 |
|
huffman@29164
|
1252 |
subsection {* Sine and Cosine *}
|
huffman@29164
|
1253 |
|
huffman@29164
|
1254 |
definition
|
huffman@31271
|
1255 |
sin_coeff :: "nat \<Rightarrow> real" where
|
huffman@31271
|
1256 |
"sin_coeff = (\<lambda>n. if even n then 0 else -1 ^ ((n - Suc 0) div 2) / real (fact n))"
|
huffman@31271
|
1257 |
|
huffman@31271
|
1258 |
definition
|
huffman@31271
|
1259 |
cos_coeff :: "nat \<Rightarrow> real" where
|
huffman@31271
|
1260 |
"cos_coeff = (\<lambda>n. if even n then (-1 ^ (n div 2)) / real (fact n) else 0)"
|
huffman@31271
|
1261 |
|
huffman@31271
|
1262 |
definition
|
huffman@29164
|
1263 |
sin :: "real => real" where
|
huffman@31271
|
1264 |
"sin x = (\<Sum>n. sin_coeff n * x ^ n)"
|
huffman@31271
|
1265 |
|
huffman@29164
|
1266 |
definition
|
huffman@29164
|
1267 |
cos :: "real => real" where
|
huffman@31271
|
1268 |
"cos x = (\<Sum>n. cos_coeff n * x ^ n)"
|
huffman@31271
|
1269 |
|
huffman@31271
|
1270 |
lemma summable_sin: "summable (\<lambda>n. sin_coeff n * x ^ n)"
|
huffman@31271
|
1271 |
unfolding sin_coeff_def
|
huffman@29164
|
1272 |
apply (rule_tac g = "(%n. inverse (real (fact n)) * \<bar>x\<bar> ^ n)" in summable_comparison_test)
|
huffman@29164
|
1273 |
apply (rule_tac [2] summable_exp)
|
huffman@29164
|
1274 |
apply (rule_tac x = 0 in exI)
|
huffman@29164
|
1275 |
apply (auto simp add: divide_inverse abs_mult power_abs [symmetric] zero_le_mult_iff)
|
huffman@29164
|
1276 |
done
|
huffman@29164
|
1277 |
|
huffman@31271
|
1278 |
lemma summable_cos: "summable (\<lambda>n. cos_coeff n * x ^ n)"
|
huffman@31271
|
1279 |
unfolding cos_coeff_def
|
huffman@29164
|
1280 |
apply (rule_tac g = "(%n. inverse (real (fact n)) * \<bar>x\<bar> ^ n)" in summable_comparison_test)
|
huffman@29164
|
1281 |
apply (rule_tac [2] summable_exp)
|
huffman@29164
|
1282 |
apply (rule_tac x = 0 in exI)
|
huffman@29164
|
1283 |
apply (auto simp add: divide_inverse abs_mult power_abs [symmetric] zero_le_mult_iff)
|
huffman@29164
|
1284 |
done
|
huffman@29164
|
1285 |
|
huffman@29164
|
1286 |
lemma lemma_STAR_sin:
|
huffman@29164
|
1287 |
"(if even n then 0
|
huffman@29164
|
1288 |
else -1 ^ ((n - Suc 0) div 2)/(real (fact n))) * 0 ^ n = 0"
|
huffman@29164
|
1289 |
by (induct "n", auto)
|
huffman@29164
|
1290 |
|
huffman@29164
|
1291 |
lemma lemma_STAR_cos:
|
huffman@29164
|
1292 |
"0 < n -->
|
huffman@29164
|
1293 |
-1 ^ (n div 2)/(real (fact n)) * 0 ^ n = 0"
|
huffman@29164
|
1294 |
by (induct "n", auto)
|
huffman@29164
|
1295 |
|
huffman@29164
|
1296 |
lemma lemma_STAR_cos1:
|
huffman@29164
|
1297 |
"0 < n -->
|
huffman@29164
|
1298 |
(-1) ^ (n div 2)/(real (fact n)) * 0 ^ n = 0"
|
huffman@29164
|
1299 |
by (induct "n", auto)
|
huffman@29164
|
1300 |
|
huffman@29164
|
1301 |
lemma lemma_STAR_cos2:
|
huffman@29164
|
1302 |
"(\<Sum>n=1..<n. if even n then -1 ^ (n div 2)/(real (fact n)) * 0 ^ n
|
huffman@29164
|
1303 |
else 0) = 0"
|
huffman@29164
|
1304 |
apply (induct "n")
|
huffman@29164
|
1305 |
apply (case_tac [2] "n", auto)
|
huffman@29164
|
1306 |
done
|
huffman@29164
|
1307 |
|
huffman@31271
|
1308 |
lemma sin_converges: "(\<lambda>n. sin_coeff n * x ^ n) sums sin(x)"
|
huffman@29164
|
1309 |
unfolding sin_def by (rule summable_sin [THEN summable_sums])
|
huffman@29164
|
1310 |
|
huffman@31271
|
1311 |
lemma cos_converges: "(\<lambda>n. cos_coeff n * x ^ n) sums cos(x)"
|
huffman@29164
|
1312 |
unfolding cos_def by (rule summable_cos [THEN summable_sums])
|
huffman@29164
|
1313 |
|
huffman@31271
|
1314 |
lemma sin_fdiffs: "diffs sin_coeff = cos_coeff"
|
huffman@31271
|
1315 |
unfolding sin_coeff_def cos_coeff_def
|
huffman@29164
|
1316 |
by (auto intro!: ext
|
huffman@29164
|
1317 |
simp add: diffs_def divide_inverse real_of_nat_def of_nat_mult
|
huffman@29164
|
1318 |
simp del: mult_Suc of_nat_Suc)
|
huffman@29164
|
1319 |
|
huffman@31271
|
1320 |
lemma sin_fdiffs2: "diffs sin_coeff n = cos_coeff n"
|
huffman@29164
|
1321 |
by (simp only: sin_fdiffs)
|
huffman@29164
|
1322 |
|
huffman@31271
|
1323 |
lemma cos_fdiffs: "diffs cos_coeff = (\<lambda>n. - sin_coeff n)"
|
huffman@31271
|
1324 |
unfolding sin_coeff_def cos_coeff_def
|
huffman@29164
|
1325 |
by (auto intro!: ext
|
huffman@29164
|
1326 |
simp add: diffs_def divide_inverse odd_Suc_mult_two_ex real_of_nat_def of_nat_mult
|
huffman@29164
|
1327 |
simp del: mult_Suc of_nat_Suc)
|
huffman@29164
|
1328 |
|
huffman@31271
|
1329 |
lemma cos_fdiffs2: "diffs cos_coeff n = - sin_coeff n"
|
huffman@29164
|
1330 |
by (simp only: cos_fdiffs)
|
huffman@29164
|
1331 |
|
huffman@29164
|
1332 |
text{*Now at last we can get the derivatives of exp, sin and cos*}
|
huffman@29164
|
1333 |
|
huffman@31271
|
1334 |
lemma lemma_sin_minus: "- sin x = (\<Sum>n. - (sin_coeff n * x ^ n))"
|
huffman@29164
|
1335 |
by (auto intro!: sums_unique sums_minus sin_converges)
|
huffman@29164
|
1336 |
|
huffman@31271
|
1337 |
lemma lemma_sin_ext: "sin = (\<lambda>x. \<Sum>n. sin_coeff n * x ^ n)"
|
huffman@29164
|
1338 |
by (auto intro!: ext simp add: sin_def)
|
huffman@29164
|
1339 |
|
huffman@31271
|
1340 |
lemma lemma_cos_ext: "cos = (\<lambda>x. \<Sum>n. cos_coeff n * x ^ n)"
|
huffman@29164
|
1341 |
by (auto intro!: ext simp add: cos_def)
|
huffman@29164
|
1342 |
|
huffman@29164
|
1343 |
lemma DERIV_sin [simp]: "DERIV sin x :> cos(x)"
|
huffman@29164
|
1344 |
apply (simp add: cos_def)
|
huffman@29164
|
1345 |
apply (subst lemma_sin_ext)
|
huffman@29164
|
1346 |
apply (auto simp add: sin_fdiffs2 [symmetric])
|
huffman@29164
|
1347 |
apply (rule_tac K = "1 + \<bar>x\<bar>" in termdiffs)
|
huffman@29164
|
1348 |
apply (auto intro: sin_converges cos_converges sums_summable intro!: sums_minus [THEN sums_summable] simp add: cos_fdiffs sin_fdiffs)
|
huffman@29164
|
1349 |
done
|
huffman@29164
|
1350 |
|
huffman@29164
|
1351 |
lemma DERIV_cos [simp]: "DERIV cos x :> -sin(x)"
|
huffman@29164
|
1352 |
apply (subst lemma_cos_ext)
|
huffman@29164
|
1353 |
apply (auto simp add: lemma_sin_minus cos_fdiffs2 [symmetric] minus_mult_left)
|
huffman@29164
|
1354 |
apply (rule_tac K = "1 + \<bar>x\<bar>" in termdiffs)
|
huffman@29164
|
1355 |
apply (auto intro: sin_converges cos_converges sums_summable intro!: sums_minus [THEN sums_summable] simp add: cos_fdiffs sin_fdiffs diffs_minus)
|
huffman@29164
|
1356 |
done
|
huffman@29164
|
1357 |
|
huffman@29164
|
1358 |
lemma isCont_sin [simp]: "isCont sin x"
|
huffman@29164
|
1359 |
by (rule DERIV_sin [THEN DERIV_isCont])
|
huffman@29164
|
1360 |
|
huffman@29164
|
1361 |
lemma isCont_cos [simp]: "isCont cos x"
|
huffman@29164
|
1362 |
by (rule DERIV_cos [THEN DERIV_isCont])
|
huffman@29164
|
1363 |
|
huffman@29164
|
1364 |
|
hoelzl@31879
|
1365 |
declare
|
hoelzl@31879
|
1366 |
DERIV_exp[THEN DERIV_chain2, THEN DERIV_cong, DERIV_intros]
|
hoelzl@31879
|
1367 |
DERIV_ln[THEN DERIV_chain2, THEN DERIV_cong, DERIV_intros]
|
hoelzl@31879
|
1368 |
DERIV_sin[THEN DERIV_chain2, THEN DERIV_cong, DERIV_intros]
|
hoelzl@31879
|
1369 |
DERIV_cos[THEN DERIV_chain2, THEN DERIV_cong, DERIV_intros]
|
hoelzl@31879
|
1370 |
|
huffman@29164
|
1371 |
subsection {* Properties of Sine and Cosine *}
|
paulson@15077
|
1372 |
|
paulson@15077
|
1373 |
lemma sin_zero [simp]: "sin 0 = 0"
|
huffman@31271
|
1374 |
unfolding sin_def sin_coeff_def by (simp add: powser_zero)
|
paulson@15077
|
1375 |
|
paulson@15077
|
1376 |
lemma cos_zero [simp]: "cos 0 = 1"
|
huffman@31271
|
1377 |
unfolding cos_def cos_coeff_def by (simp add: powser_zero)
|
paulson@15077
|
1378 |
|
paulson@15077
|
1379 |
lemma DERIV_sin_sin_mult [simp]:
|
paulson@15077
|
1380 |
"DERIV (%x. sin(x)*sin(x)) x :> cos(x) * sin(x) + cos(x) * sin(x)"
|
paulson@15077
|
1381 |
by (rule DERIV_mult, auto)
|
paulson@15077
|
1382 |
|
paulson@15077
|
1383 |
lemma DERIV_sin_sin_mult2 [simp]:
|
paulson@15077
|
1384 |
"DERIV (%x. sin(x)*sin(x)) x :> 2 * cos(x) * sin(x)"
|
paulson@15077
|
1385 |
apply (cut_tac x = x in DERIV_sin_sin_mult)
|
paulson@15077
|
1386 |
apply (auto simp add: mult_assoc)
|
paulson@15077
|
1387 |
done
|
paulson@15077
|
1388 |
|
paulson@15077
|
1389 |
lemma DERIV_sin_realpow2 [simp]:
|
paulson@15077
|
1390 |
"DERIV (%x. (sin x)\<twosuperior>) x :> cos(x) * sin(x) + cos(x) * sin(x)"
|
paulson@15077
|
1391 |
by (auto simp add: numeral_2_eq_2 real_mult_assoc [symmetric])
|
paulson@15077
|
1392 |
|
paulson@15077
|
1393 |
lemma DERIV_sin_realpow2a [simp]:
|
paulson@15077
|
1394 |
"DERIV (%x. (sin x)\<twosuperior>) x :> 2 * cos(x) * sin(x)"
|
paulson@15077
|
1395 |
by (auto simp add: numeral_2_eq_2)
|
paulson@15077
|
1396 |
|
paulson@15077
|
1397 |
lemma DERIV_cos_cos_mult [simp]:
|
paulson@15077
|
1398 |
"DERIV (%x. cos(x)*cos(x)) x :> -sin(x) * cos(x) + -sin(x) * cos(x)"
|
paulson@15077
|
1399 |
by (rule DERIV_mult, auto)
|
paulson@15077
|
1400 |
|
paulson@15077
|
1401 |
lemma DERIV_cos_cos_mult2 [simp]:
|
paulson@15077
|
1402 |
"DERIV (%x. cos(x)*cos(x)) x :> -2 * cos(x) * sin(x)"
|
paulson@15077
|
1403 |
apply (cut_tac x = x in DERIV_cos_cos_mult)
|
paulson@15077
|
1404 |
apply (auto simp add: mult_ac)
|
paulson@15077
|
1405 |
done
|
paulson@15077
|
1406 |
|
paulson@15077
|
1407 |
lemma DERIV_cos_realpow2 [simp]:
|
paulson@15077
|
1408 |
"DERIV (%x. (cos x)\<twosuperior>) x :> -sin(x) * cos(x) + -sin(x) * cos(x)"
|
paulson@15077
|
1409 |
by (auto simp add: numeral_2_eq_2 real_mult_assoc [symmetric])
|
paulson@15077
|
1410 |
|
paulson@15077
|
1411 |
lemma DERIV_cos_realpow2a [simp]:
|
paulson@15077
|
1412 |
"DERIV (%x. (cos x)\<twosuperior>) x :> -2 * cos(x) * sin(x)"
|
paulson@15077
|
1413 |
by (auto simp add: numeral_2_eq_2)
|
paulson@15077
|
1414 |
|
paulson@15077
|
1415 |
lemma lemma_DERIV_subst: "[| DERIV f x :> D; D = E |] ==> DERIV f x :> E"
|
paulson@15077
|
1416 |
by auto
|
paulson@15077
|
1417 |
|
paulson@15077
|
1418 |
lemma DERIV_cos_realpow2b: "DERIV (%x. (cos x)\<twosuperior>) x :> -(2 * cos(x) * sin(x))"
|
paulson@15077
|
1419 |
apply (rule lemma_DERIV_subst)
|
paulson@15077
|
1420 |
apply (rule DERIV_cos_realpow2a, auto)
|
paulson@15077
|
1421 |
done
|
paulson@15077
|
1422 |
|
paulson@15077
|
1423 |
(* most useful *)
|
paulson@15229
|
1424 |
lemma DERIV_cos_cos_mult3 [simp]:
|
paulson@15229
|
1425 |
"DERIV (%x. cos(x)*cos(x)) x :> -(2 * cos(x) * sin(x))"
|
paulson@15077
|
1426 |
apply (rule lemma_DERIV_subst)
|
paulson@15077
|
1427 |
apply (rule DERIV_cos_cos_mult2, auto)
|
paulson@15077
|
1428 |
done
|
paulson@15077
|
1429 |
|
paulson@15077
|
1430 |
lemma DERIV_sin_circle_all:
|
paulson@15077
|
1431 |
"\<forall>x. DERIV (%x. (sin x)\<twosuperior> + (cos x)\<twosuperior>) x :>
|
paulson@15077
|
1432 |
(2*cos(x)*sin(x) - 2*cos(x)*sin(x))"
|
paulson@15229
|
1433 |
apply (simp only: diff_minus, safe)
|
paulson@15229
|
1434 |
apply (rule DERIV_add)
|
paulson@15077
|
1435 |
apply (auto simp add: numeral_2_eq_2)
|
paulson@15077
|
1436 |
done
|
paulson@15077
|
1437 |
|
paulson@15229
|
1438 |
lemma DERIV_sin_circle_all_zero [simp]:
|
paulson@15229
|
1439 |
"\<forall>x. DERIV (%x. (sin x)\<twosuperior> + (cos x)\<twosuperior>) x :> 0"
|
paulson@15077
|
1440 |
by (cut_tac DERIV_sin_circle_all, auto)
|
paulson@15077
|
1441 |
|
paulson@15077
|
1442 |
lemma sin_cos_squared_add [simp]: "((sin x)\<twosuperior>) + ((cos x)\<twosuperior>) = 1"
|
paulson@15077
|
1443 |
apply (cut_tac x = x and y = 0 in DERIV_sin_circle_all_zero [THEN DERIV_isconst_all])
|
paulson@15077
|
1444 |
apply (auto simp add: numeral_2_eq_2)
|
paulson@15077
|
1445 |
done
|
paulson@15077
|
1446 |
|
paulson@15077
|
1447 |
lemma sin_cos_squared_add2 [simp]: "((cos x)\<twosuperior>) + ((sin x)\<twosuperior>) = 1"
|
huffman@23286
|
1448 |
apply (subst add_commute)
|
huffman@30269
|
1449 |
apply (rule sin_cos_squared_add)
|
paulson@15077
|
1450 |
done
|
paulson@15077
|
1451 |
|
paulson@15077
|
1452 |
lemma sin_cos_squared_add3 [simp]: "cos x * cos x + sin x * sin x = 1"
|
paulson@15077
|
1453 |
apply (cut_tac x = x in sin_cos_squared_add2)
|
huffman@30269
|
1454 |
apply (simp add: power2_eq_square)
|
paulson@15077
|
1455 |
done
|
paulson@15077
|
1456 |
|
paulson@15077
|
1457 |
lemma sin_squared_eq: "(sin x)\<twosuperior> = 1 - (cos x)\<twosuperior>"
|
paulson@15229
|
1458 |
apply (rule_tac a1 = "(cos x)\<twosuperior>" in add_right_cancel [THEN iffD1])
|
huffman@30269
|
1459 |
apply simp
|
paulson@15077
|
1460 |
done
|
paulson@15077
|
1461 |
|
paulson@15077
|
1462 |
lemma cos_squared_eq: "(cos x)\<twosuperior> = 1 - (sin x)\<twosuperior>"
|
paulson@15077
|
1463 |
apply (rule_tac a1 = "(sin x)\<twosuperior>" in add_right_cancel [THEN iffD1])
|
huffman@30269
|
1464 |
apply simp
|
paulson@15077
|
1465 |
done
|
paulson@15077
|
1466 |
|
paulson@15081
|
1467 |
lemma abs_sin_le_one [simp]: "\<bar>sin x\<bar> \<le> 1"
|
huffman@23097
|
1468 |
by (rule power2_le_imp_le, simp_all add: sin_squared_eq)
|
paulson@15077
|
1469 |
|
paulson@15077
|
1470 |
lemma sin_ge_minus_one [simp]: "-1 \<le> sin x"
|
paulson@15077
|
1471 |
apply (insert abs_sin_le_one [of x])
|
huffman@22998
|
1472 |
apply (simp add: abs_le_iff del: abs_sin_le_one)
|
paulson@15077
|
1473 |
done
|
paulson@15077
|
1474 |
|
paulson@15077
|
1475 |
lemma sin_le_one [simp]: "sin x \<le> 1"
|
paulson@15077
|
1476 |
apply (insert abs_sin_le_one [of x])
|
huffman@22998
|
1477 |
apply (simp add: abs_le_iff del: abs_sin_le_one)
|
paulson@15077
|
1478 |
done
|
paulson@15077
|
1479 |
|
paulson@15081
|
1480 |
lemma abs_cos_le_one [simp]: "\<bar>cos x\<bar> \<le> 1"
|
huffman@23097
|
1481 |
by (rule power2_le_imp_le, simp_all add: cos_squared_eq)
|
paulson@15077
|
1482 |
|
paulson@15077
|
1483 |
lemma cos_ge_minus_one [simp]: "-1 \<le> cos x"
|
paulson@15077
|
1484 |
apply (insert abs_cos_le_one [of x])
|
huffman@22998
|
1485 |
apply (simp add: abs_le_iff del: abs_cos_le_one)
|
paulson@15077
|
1486 |
done
|
paulson@15077
|
1487 |
|
paulson@15077
|
1488 |
lemma cos_le_one [simp]: "cos x \<le> 1"
|
paulson@15077
|
1489 |
apply (insert abs_cos_le_one [of x])
|
huffman@22998
|
1490 |
apply (simp add: abs_le_iff del: abs_cos_le_one)
|
paulson@15077
|
1491 |
done
|
paulson@15077
|
1492 |
|
paulson@15077
|
1493 |
lemma DERIV_fun_pow: "DERIV g x :> m ==>
|
paulson@15077
|
1494 |
DERIV (%x. (g x) ^ n) x :> real n * (g x) ^ (n - 1) * m"
|
huffman@30019
|
1495 |
unfolding One_nat_def
|
paulson@15077
|
1496 |
apply (rule lemma_DERIV_subst)
|
paulson@15229
|
1497 |
apply (rule_tac f = "(%x. x ^ n)" in DERIV_chain2)
|
paulson@15077
|
1498 |
apply (rule DERIV_pow, auto)
|
paulson@15077
|
1499 |
done
|
paulson@15077
|
1500 |
|
paulson@15229
|
1501 |
lemma DERIV_fun_exp:
|
paulson@15229
|
1502 |
"DERIV g x :> m ==> DERIV (%x. exp(g x)) x :> exp(g x) * m"
|
paulson@15077
|
1503 |
apply (rule lemma_DERIV_subst)
|
paulson@15077
|
1504 |
apply (rule_tac f = exp in DERIV_chain2)
|
paulson@15077
|
1505 |
apply (rule DERIV_exp, auto)
|
paulson@15077
|
1506 |
done
|
paulson@15077
|
1507 |
|
paulson@15229
|
1508 |
lemma DERIV_fun_sin:
|
paulson@15229
|
1509 |
"DERIV g x :> m ==> DERIV (%x. sin(g x)) x :> cos(g x) * m"
|
paulson@15077
|
1510 |
apply (rule lemma_DERIV_subst)
|
paulson@15077
|
1511 |
apply (rule_tac f = sin in DERIV_chain2)
|
paulson@15077
|
1512 |
apply (rule DERIV_sin, auto)
|
paulson@15077
|
1513 |
done
|
paulson@15077
|
1514 |
|
paulson@15229
|
1515 |
lemma DERIV_fun_cos:
|
paulson@15229
|
1516 |
"DERIV g x :> m ==> DERIV (%x. cos(g x)) x :> -sin(g x) * m"
|
paulson@15077
|
1517 |
apply (rule lemma_DERIV_subst)
|
paulson@15077
|
1518 |
apply (rule_tac f = cos in DERIV_chain2)
|
paulson@15077
|
1519 |
apply (rule DERIV_cos, auto)
|
paulson@15077
|
1520 |
done
|
paulson@15077
|
1521 |
|
paulson@15077
|
1522 |
(* lemma *)
|
paulson@15229
|
1523 |
lemma lemma_DERIV_sin_cos_add:
|
paulson@15229
|
1524 |
"\<forall>x.
|
paulson@15077
|
1525 |
DERIV (%x. (sin (x + y) - (sin x * cos y + cos x * sin y)) ^ 2 +
|
paulson@15077
|
1526 |
(cos (x + y) - (cos x * cos y - sin x * sin y)) ^ 2) x :> 0"
|
paulson@15077
|
1527 |
apply (safe, rule lemma_DERIV_subst)
|
paulson@15077
|
1528 |
apply (best intro!: DERIV_intros intro: DERIV_chain2)
|
paulson@15077
|
1529 |
--{*replaces the old @{text DERIV_tac}*}
|
nipkow@29667
|
1530 |
apply (auto simp add: algebra_simps)
|
paulson@15077
|
1531 |
done
|
paulson@15077
|
1532 |
|
paulson@15077
|
1533 |
lemma sin_cos_add [simp]:
|
paulson@15077
|
1534 |
"(sin (x + y) - (sin x * cos y + cos x * sin y)) ^ 2 +
|
paulson@15077
|
1535 |
(cos (x + y) - (cos x * cos y - sin x * sin y)) ^ 2 = 0"
|
paulson@15077
|
1536 |
apply (cut_tac y = 0 and x = x and y7 = y
|
paulson@15077
|
1537 |
in lemma_DERIV_sin_cos_add [THEN DERIV_isconst_all])
|
paulson@15077
|
1538 |
apply (auto simp add: numeral_2_eq_2)
|
paulson@15077
|
1539 |
done
|
paulson@15077
|
1540 |
|
paulson@15077
|
1541 |
lemma sin_add: "sin (x + y) = sin x * cos y + cos x * sin y"
|
paulson@15077
|
1542 |
apply (cut_tac x = x and y = y in sin_cos_add)
|
huffman@22969
|
1543 |
apply (simp del: sin_cos_add)
|
paulson@15077
|
1544 |
done
|
paulson@15077
|
1545 |
|
paulson@15077
|
1546 |
lemma cos_add: "cos (x + y) = cos x * cos y - sin x * sin y"
|
paulson@15077
|
1547 |
apply (cut_tac x = x and y = y in sin_cos_add)
|
huffman@22969
|
1548 |
apply (simp del: sin_cos_add)
|
paulson@15077
|
1549 |
done
|
paulson@15077
|
1550 |
|
paulson@15085
|
1551 |
lemma lemma_DERIV_sin_cos_minus:
|
paulson@15085
|
1552 |
"\<forall>x. DERIV (%x. (sin(-x) + (sin x)) ^ 2 + (cos(-x) - (cos x)) ^ 2) x :> 0"
|
paulson@15077
|
1553 |
apply (safe, rule lemma_DERIV_subst)
|
nipkow@29667
|
1554 |
apply (best intro!: DERIV_intros intro: DERIV_chain2)
|
nipkow@29667
|
1555 |
apply (simp add: algebra_simps)
|
paulson@15077
|
1556 |
done
|
paulson@15077
|
1557 |
|
huffman@29165
|
1558 |
lemma sin_cos_minus:
|
paulson@15085
|
1559 |
"(sin(-x) + (sin x)) ^ 2 + (cos(-x) - (cos x)) ^ 2 = 0"
|
paulson@15085
|
1560 |
apply (cut_tac y = 0 and x = x
|
paulson@15085
|
1561 |
in lemma_DERIV_sin_cos_minus [THEN DERIV_isconst_all])
|
huffman@22969
|
1562 |
apply simp
|
paulson@15077
|
1563 |
done
|
paulson@15077
|
1564 |
|
paulson@15077
|
1565 |
lemma sin_minus [simp]: "sin (-x) = -sin(x)"
|
huffman@29165
|
1566 |
using sin_cos_minus [where x=x] by simp
|
paulson@15077
|
1567 |
|
paulson@15077
|
1568 |
lemma cos_minus [simp]: "cos (-x) = cos(x)"
|
huffman@29165
|
1569 |
using sin_cos_minus [where x=x] by simp
|
paulson@15077
|
1570 |
|
paulson@15077
|
1571 |
lemma sin_diff: "sin (x - y) = sin x * cos y - cos x * sin y"
|
huffman@22969
|
1572 |
by (simp add: diff_minus sin_add)
|
paulson@15077
|
1573 |
|
paulson@15077
|
1574 |
lemma sin_diff2: "sin (x - y) = cos y * sin x - sin y * cos x"
|
paulson@15077
|
1575 |
by (simp add: sin_diff mult_commute)
|
paulson@15077
|
1576 |
|
paulson@15077
|
1577 |
lemma cos_diff: "cos (x - y) = cos x * cos y + sin x * sin y"
|
huffman@22969
|
1578 |
by (simp add: diff_minus cos_add)
|
paulson@15077
|
1579 |
|
paulson@15077
|
1580 |
lemma cos_diff2: "cos (x - y) = cos y * cos x + sin y * sin x"
|
paulson@15077
|
1581 |
by (simp add: cos_diff mult_commute)
|
paulson@15077
|
1582 |
|
paulson@15077
|
1583 |
lemma sin_double [simp]: "sin(2 * x) = 2* sin x * cos x"
|
huffman@29165
|
1584 |
using sin_add [where x=x and y=x] by simp
|
paulson@15077
|
1585 |
|
paulson@15077
|
1586 |
lemma cos_double: "cos(2* x) = ((cos x)\<twosuperior>) - ((sin x)\<twosuperior>)"
|
huffman@29165
|
1587 |
using cos_add [where x=x and y=x]
|
huffman@29165
|
1588 |
by (simp add: power2_eq_square)
|
paulson@15077
|
1589 |
|
paulson@15077
|
1590 |
|
huffman@29164
|
1591 |
subsection {* The Constant Pi *}
|
paulson@15077
|
1592 |
|
huffman@23043
|
1593 |
definition
|
huffman@23043
|
1594 |
pi :: "real" where
|
huffman@23053
|
1595 |
"pi = 2 * (THE x. 0 \<le> (x::real) & x \<le> 2 & cos x = 0)"
|
huffman@23043
|
1596 |
|
paulson@15077
|
1597 |
text{*Show that there's a least positive @{term x} with @{term "cos(x) = 0"};
|
paulson@15077
|
1598 |
hence define pi.*}
|
paulson@15077
|
1599 |
|
paulson@15077
|
1600 |
lemma sin_paired:
|
huffman@23177
|
1601 |
"(%n. -1 ^ n /(real (fact (2 * n + 1))) * x ^ (2 * n + 1))
|
paulson@15077
|
1602 |
sums sin x"
|
paulson@15077
|
1603 |
proof -
|
huffman@31271
|
1604 |
have "(\<lambda>n. \<Sum>k = n * 2..<n * 2 + 2. sin_coeff k * x ^ k) sums sin x"
|
huffman@23176
|
1605 |
unfolding sin_def
|
paulson@15077
|
1606 |
by (rule sin_converges [THEN sums_summable, THEN sums_group], simp)
|
huffman@31271
|
1607 |
thus ?thesis unfolding One_nat_def sin_coeff_def by (simp add: mult_ac)
|
paulson@15077
|
1608 |
qed
|
paulson@15077
|
1609 |
|
huffman@30269
|
1610 |
text {* FIXME: This is a long, ugly proof! *}
|
paulson@15077
|
1611 |
lemma sin_gt_zero: "[|0 < x; x < 2 |] ==> 0 < sin x"
|
paulson@15077
|
1612 |
apply (subgoal_tac
|
paulson@15077
|
1613 |
"(\<lambda>n. \<Sum>k = n * 2..<n * 2 + 2.
|
huffman@23177
|
1614 |
-1 ^ k / real (fact (2 * k + 1)) * x ^ (2 * k + 1))
|
huffman@23177
|
1615 |
sums (\<Sum>n. -1 ^ n / real (fact (2 * n + 1)) * x ^ (2 * n + 1))")
|
paulson@15077
|
1616 |
prefer 2
|
paulson@15077
|
1617 |
apply (rule sin_paired [THEN sums_summable, THEN sums_group], simp)
|
paulson@15077
|
1618 |
apply (rotate_tac 2)
|
paulson@15077
|
1619 |
apply (drule sin_paired [THEN sums_unique, THEN ssubst])
|
huffman@30019
|
1620 |
unfolding One_nat_def
|
huffman@30269
|
1621 |
apply (auto simp del: fact_Suc)
|
paulson@15077
|
1622 |
apply (frule sums_unique)
|
huffman@30269
|
1623 |
apply (auto simp del: fact_Suc)
|
paulson@15077
|
1624 |
apply (rule_tac n1 = 0 in series_pos_less [THEN [2] order_le_less_trans])
|
huffman@30269
|
1625 |
apply (auto simp del: fact_Suc)
|
paulson@15077
|
1626 |
apply (erule sums_summable)
|
paulson@15077
|
1627 |
apply (case_tac "m=0")
|
paulson@15077
|
1628 |
apply (simp (no_asm_simp))
|
paulson@15234
|
1629 |
apply (subgoal_tac "6 * (x * (x * x) / real (Suc (Suc (Suc (Suc (Suc (Suc 0))))))) < 6 * x")
|
nipkow@15539
|
1630 |
apply (simp only: mult_less_cancel_left, simp)
|
nipkow@15539
|
1631 |
apply (simp (no_asm_simp) add: numeral_2_eq_2 [symmetric] mult_assoc [symmetric])
|
paulson@15077
|
1632 |
apply (subgoal_tac "x*x < 2*3", simp)
|
paulson@15077
|
1633 |
apply (rule mult_strict_mono)
|
paulson@15085
|
1634 |
apply (auto simp add: real_0_less_add_iff real_of_nat_Suc simp del: fact_Suc)
|
paulson@15077
|
1635 |
apply (subst fact_Suc)
|
paulson@15077
|
1636 |
apply (subst fact_Suc)
|
paulson@15077
|
1637 |
apply (subst fact_Suc)
|
paulson@15077
|
1638 |
apply (subst fact_Suc)
|
paulson@15077
|
1639 |
apply (subst real_of_nat_mult)
|
paulson@15077
|
1640 |
apply (subst real_of_nat_mult)
|
paulson@15077
|
1641 |
apply (subst real_of_nat_mult)
|
paulson@15077
|
1642 |
apply (subst real_of_nat_mult)
|
nipkow@15539
|
1643 |
apply (simp (no_asm) add: divide_inverse del: fact_Suc)
|
paulson@15077
|
1644 |
apply (auto simp add: mult_assoc [symmetric] simp del: fact_Suc)
|
paulson@15077
|
1645 |
apply (rule_tac c="real (Suc (Suc (4*m)))" in mult_less_imp_less_right)
|
paulson@15077
|
1646 |
apply (auto simp add: mult_assoc simp del: fact_Suc)
|
paulson@15077
|
1647 |
apply (rule_tac c="real (Suc (Suc (Suc (4*m))))" in mult_less_imp_less_right)
|
paulson@15077
|
1648 |
apply (auto simp add: mult_assoc mult_less_cancel_left simp del: fact_Suc)
|
paulson@15077
|
1649 |
apply (subgoal_tac "x * (x * x ^ (4*m)) = (x ^ (4*m)) * (x * x)")
|
paulson@15077
|
1650 |
apply (erule ssubst)+
|
paulson@15077
|
1651 |
apply (auto simp del: fact_Suc)
|
paulson@15077
|
1652 |
apply (subgoal_tac "0 < x ^ (4 * m) ")
|
paulson@15077
|
1653 |
prefer 2 apply (simp only: zero_less_power)
|
paulson@15077
|
1654 |
apply (simp (no_asm_simp) add: mult_less_cancel_left)
|
paulson@15077
|
1655 |
apply (rule mult_strict_mono)
|
paulson@15077
|
1656 |
apply (simp_all (no_asm_simp))
|
paulson@15077
|
1657 |
done
|
paulson@15077
|
1658 |
|
paulson@15077
|
1659 |
lemma sin_gt_zero1: "[|0 < x; x < 2 |] ==> 0 < sin x"
|
paulson@15077
|
1660 |
by (auto intro: sin_gt_zero)
|
paulson@15077
|
1661 |
|
paulson@15077
|
1662 |
lemma cos_double_less_one: "[| 0 < x; x < 2 |] ==> cos (2 * x) < 1"
|
paulson@15077
|
1663 |
apply (cut_tac x = x in sin_gt_zero1)
|
paulson@15077
|
1664 |
apply (auto simp add: cos_squared_eq cos_double)
|
paulson@15077
|
1665 |
done
|
paulson@15077
|
1666 |
|
paulson@15077
|
1667 |
lemma cos_paired:
|
huffman@23177
|
1668 |
"(%n. -1 ^ n /(real (fact (2 * n))) * x ^ (2 * n)) sums cos x"
|
paulson@15077
|
1669 |
proof -
|
huffman@31271
|
1670 |
have "(\<lambda>n. \<Sum>k = n * 2..<n * 2 + 2. cos_coeff k * x ^ k) sums cos x"
|
huffman@23176
|
1671 |
unfolding cos_def
|
paulson@15077
|
1672 |
by (rule cos_converges [THEN sums_summable, THEN sums_group], simp)
|
huffman@31271
|
1673 |
thus ?thesis unfolding cos_coeff_def by (simp add: mult_ac)
|
paulson@15077
|
1674 |
qed
|
paulson@15077
|
1675 |
|
paulson@15077
|
1676 |
lemma fact_lemma: "real (n::nat) * 4 = real (4 * n)"
|
paulson@15077
|
1677 |
by simp
|
paulson@15077
|
1678 |
|
huffman@23053
|
1679 |
lemma cos_two_less_zero [simp]: "cos (2) < 0"
|
paulson@15077
|
1680 |
apply (cut_tac x = 2 in cos_paired)
|
paulson@15077
|
1681 |
apply (drule sums_minus)
|
paulson@15077
|
1682 |
apply (rule neg_less_iff_less [THEN iffD1])
|
nipkow@15539
|
1683 |
apply (frule sums_unique, auto)
|
nipkow@15539
|
1684 |
apply (rule_tac y =
|
huffman@23177
|
1685 |
"\<Sum>n=0..< Suc(Suc(Suc 0)). - (-1 ^ n / (real(fact (2*n))) * 2 ^ (2*n))"
|
paulson@15481
|
1686 |
in order_less_trans)
|
huffman@30269
|
1687 |
apply (simp (no_asm) add: fact_num_eq_if realpow_num_eq_if del: fact_Suc)
|
nipkow@15561
|
1688 |
apply (simp (no_asm) add: mult_assoc del: setsum_op_ivl_Suc)
|
paulson@15077
|
1689 |
apply (rule sumr_pos_lt_pair)
|
paulson@15077
|
1690 |
apply (erule sums_summable, safe)
|
huffman@30019
|
1691 |
unfolding One_nat_def
|
paulson@15085
|
1692 |
apply (simp (no_asm) add: divide_inverse real_0_less_add_iff mult_assoc [symmetric]
|
paulson@15085
|
1693 |
del: fact_Suc)
|
paulson@15077
|
1694 |
apply (rule real_mult_inverse_cancel2)
|
paulson@15077
|
1695 |
apply (rule real_of_nat_fact_gt_zero)+
|
paulson@15077
|
1696 |
apply (simp (no_asm) add: mult_assoc [symmetric] del: fact_Suc)
|
paulson@15077
|
1697 |
apply (subst fact_lemma)
|
paulson@15481
|
1698 |
apply (subst fact_Suc [of "Suc (Suc (Suc (Suc (Suc (Suc (Suc (4 * d)))))))"])
|
paulson@15481
|
1699 |
apply (simp only: real_of_nat_mult)
|
huffman@23007
|
1700 |
apply (rule mult_strict_mono, force)
|
huffman@27483
|
1701 |
apply (rule_tac [3] real_of_nat_ge_zero)
|
paulson@15481
|
1702 |
prefer 2 apply force
|
paulson@15077
|
1703 |
apply (rule real_of_nat_less_iff [THEN iffD2])
|
paulson@15077
|
1704 |
apply (rule fact_less_mono, auto)
|
paulson@15077
|
1705 |
done
|
huffman@23053
|
1706 |
|
huffman@23053
|
1707 |
lemmas cos_two_neq_zero [simp] = cos_two_less_zero [THEN less_imp_neq]
|
huffman@23053
|
1708 |
lemmas cos_two_le_zero [simp] = cos_two_less_zero [THEN order_less_imp_le]
|
paulson@15077
|
1709 |
|
paulson@15077
|
1710 |
lemma cos_is_zero: "EX! x. 0 \<le> x & x \<le> 2 & cos x = 0"
|
paulson@15077
|
1711 |
apply (subgoal_tac "\<exists>x. 0 \<le> x & x \<le> 2 & cos x = 0")
|
paulson@15077
|
1712 |
apply (rule_tac [2] IVT2)
|
paulson@15077
|
1713 |
apply (auto intro: DERIV_isCont DERIV_cos)
|
paulson@15077
|
1714 |
apply (cut_tac x = xa and y = y in linorder_less_linear)
|
paulson@15077
|
1715 |
apply (rule ccontr)
|
paulson@15077
|
1716 |
apply (subgoal_tac " (\<forall>x. cos differentiable x) & (\<forall>x. isCont cos x) ")
|
paulson@15077
|
1717 |
apply (auto intro: DERIV_cos DERIV_isCont simp add: differentiable_def)
|
paulson@15077
|
1718 |
apply (drule_tac f = cos in Rolle)
|
paulson@15077
|
1719 |
apply (drule_tac [5] f = cos in Rolle)
|
paulson@15077
|
1720 |
apply (auto dest!: DERIV_cos [THEN DERIV_unique] simp add: differentiable_def)
|
paulson@15077
|
1721 |
apply (drule_tac y1 = xa in order_le_less_trans [THEN sin_gt_zero])
|
paulson@15077
|
1722 |
apply (assumption, rule_tac y=y in order_less_le_trans, simp_all)
|
paulson@15077
|
1723 |
apply (drule_tac y1 = y in order_le_less_trans [THEN sin_gt_zero], assumption, simp_all)
|
paulson@15077
|
1724 |
done
|
hoelzl@31879
|
1725 |
|
huffman@23053
|
1726 |
lemma pi_half: "pi/2 = (THE x. 0 \<le> x & x \<le> 2 & cos x = 0)"
|
paulson@15077
|
1727 |
by (simp add: pi_def)
|
paulson@15077
|
1728 |
|
paulson@15077
|
1729 |
lemma cos_pi_half [simp]: "cos (pi / 2) = 0"
|
huffman@23053
|
1730 |
by (simp add: pi_half cos_is_zero [THEN theI'])
|
huffman@23053
|
1731 |
|
huffman@23053
|
1732 |
lemma pi_half_gt_zero [simp]: "0 < pi / 2"
|
huffman@23053
|
1733 |
apply (rule order_le_neq_trans)
|
huffman@23053
|
1734 |
apply (simp add: pi_half cos_is_zero [THEN theI'])
|
huffman@23053
|
1735 |
apply (rule notI, drule arg_cong [where f=cos], simp)
|
paulson@15077
|
1736 |
done
|
paulson@15077
|
1737 |
|
huffman@23053
|
1738 |
lemmas pi_half_neq_zero [simp] = pi_half_gt_zero [THEN less_imp_neq, symmetric]
|
huffman@23053
|
1739 |
lemmas pi_half_ge_zero [simp] = pi_half_gt_zero [THEN order_less_imp_le]
|
huffman@23053
|
1740 |
|
huffman@23053
|
1741 |
lemma pi_half_less_two [simp]: "pi / 2 < 2"
|
huffman@23053
|
1742 |
apply (rule order_le_neq_trans)
|
huffman@23053
|
1743 |
apply (simp add: pi_half cos_is_zero [THEN theI'])
|
huffman@23053
|
1744 |
apply (rule notI, drule arg_cong [where f=cos], simp)
|
paulson@15077
|
1745 |
done
|
paulson@15077
|
1746 |
|
huffman@23053
|
1747 |
lemmas pi_half_neq_two [simp] = pi_half_less_two [THEN less_imp_neq]
|
huffman@23053
|
1748 |
lemmas pi_half_le_two [simp] = pi_half_less_two [THEN order_less_imp_le]
|
paulson@15077
|
1749 |
|
paulson@15077
|
1750 |
lemma pi_gt_zero [simp]: "0 < pi"
|
huffman@23053
|
1751 |
by (insert pi_half_gt_zero, simp)
|
huffman@23053
|
1752 |
|
huffman@23053
|
1753 |
lemma pi_ge_zero [simp]: "0 \<le> pi"
|
huffman@23053
|
1754 |
by (rule pi_gt_zero [THEN order_less_imp_le])
|
paulson@15077
|
1755 |
|
paulson@15077
|
1756 |
lemma pi_neq_zero [simp]: "pi \<noteq> 0"
|
huffman@22998
|
1757 |
by (rule pi_gt_zero [THEN less_imp_neq, THEN not_sym])
|
paulson@15077
|
1758 |
|
huffman@23053
|
1759 |
lemma pi_not_less_zero [simp]: "\<not> pi < 0"
|
huffman@23053
|
1760 |
by (simp add: linorder_not_less)
|
paulson@15077
|
1761 |
|
huffman@29165
|
1762 |
lemma minus_pi_half_less_zero: "-(pi/2) < 0"
|
huffman@29165
|
1763 |
by simp
|
paulson@15077
|
1764 |
|
hoelzl@29740
|
1765 |
lemma m2pi_less_pi: "- (2 * pi) < pi"
|
hoelzl@29740
|
1766 |
proof -
|
hoelzl@29740
|
1767 |
have "- (2 * pi) < 0" and "0 < pi" by auto
|
hoelzl@29740
|
1768 |
from order_less_trans[OF this] show ?thesis .
|
hoelzl@29740
|
1769 |
qed
|
hoelzl@29740
|
1770 |
|
paulson@15077
|
1771 |
lemma sin_pi_half [simp]: "sin(pi/2) = 1"
|
paulson@15077
|
1772 |
apply (cut_tac x = "pi/2" in sin_cos_squared_add2)
|
paulson@15077
|
1773 |
apply (cut_tac sin_gt_zero [OF pi_half_gt_zero pi_half_less_two])
|
huffman@23053
|
1774 |
apply (simp add: power2_eq_square)
|
paulson@15077
|
1775 |
done
|
paulson@15077
|
1776 |
|
paulson@15077
|
1777 |
lemma cos_pi [simp]: "cos pi = -1"
|
nipkow@15539
|
1778 |
by (cut_tac x = "pi/2" and y = "pi/2" in cos_add, simp)
|
paulson@15077
|
1779 |
|
paulson@15077
|
1780 |
lemma sin_pi [simp]: "sin pi = 0"
|
nipkow@15539
|
1781 |
by (cut_tac x = "pi/2" and y = "pi/2" in sin_add, simp)
|
paulson@15077
|
1782 |
|
paulson@15077
|
1783 |
lemma sin_cos_eq: "sin x = cos (pi/2 - x)"
|
paulson@15229
|
1784 |
by (simp add: diff_minus cos_add)
|
huffman@23053
|
1785 |
declare sin_cos_eq [symmetric, simp]
|
paulson@15077
|
1786 |
|
paulson@15077
|
1787 |
lemma minus_sin_cos_eq: "-sin x = cos (x + pi/2)"
|
paulson@15229
|
1788 |
by (simp add: cos_add)
|
paulson@15077
|
1789 |
declare minus_sin_cos_eq [symmetric, simp]
|
paulson@15077
|
1790 |
|
paulson@15077
|
1791 |
lemma cos_sin_eq: "cos x = sin (pi/2 - x)"
|
paulson@15229
|
1792 |
by (simp add: diff_minus sin_add)
|
huffman@23053
|
1793 |
declare cos_sin_eq [symmetric, simp]
|
paulson@15077
|
1794 |
|
paulson@15077
|
1795 |
lemma sin_periodic_pi [simp]: "sin (x + pi) = - sin x"
|
paulson@15229
|
1796 |
by (simp add: sin_add)
|
paulson@15077
|
1797 |
|
paulson@15077
|
1798 |
lemma sin_periodic_pi2 [simp]: "sin (pi + x) = - sin x"
|
paulson@15229
|
1799 |
by (simp add: sin_add)
|
paulson@15077
|
1800 |
|
paulson@15077
|
1801 |
lemma cos_periodic_pi [simp]: "cos (x + pi) = - cos x"
|
paulson@15229
|
1802 |
by (simp add: cos_add)
|
paulson@15077
|
1803 |
|
paulson@15077
|
1804 |
lemma sin_periodic [simp]: "sin (x + 2*pi) = sin x"
|
paulson@15077
|
1805 |
by (simp add: sin_add cos_double)
|
paulson@15077
|
1806 |
|
paulson@15077
|
1807 |
lemma cos_periodic [simp]: "cos (x + 2*pi) = cos x"
|
paulson@15077
|
1808 |
by (simp add: cos_add cos_double)
|
paulson@15077
|
1809 |
|
paulson@15077
|
1810 |
lemma cos_npi [simp]: "cos (real n * pi) = -1 ^ n"
|
paulson@15251
|
1811 |
apply (induct "n")
|
paulson@15077
|
1812 |
apply (auto simp add: real_of_nat_Suc left_distrib)
|
paulson@15077
|
1813 |
done
|
paulson@15077
|
1814 |
|
paulson@15383
|
1815 |
lemma cos_npi2 [simp]: "cos (pi * real n) = -1 ^ n"
|
paulson@15383
|
1816 |
proof -
|
paulson@15383
|
1817 |
have "cos (pi * real n) = cos (real n * pi)" by (simp only: mult_commute)
|
paulson@15383
|
1818 |
also have "... = -1 ^ n" by (rule cos_npi)
|
paulson@15383
|
1819 |
finally show ?thesis .
|
paulson@15383
|
1820 |
qed
|
paulson@15383
|
1821 |
|
paulson@15077
|
1822 |
lemma sin_npi [simp]: "sin (real (n::nat) * pi) = 0"
|
paulson@15251
|
1823 |
apply (induct "n")
|
paulson@15077
|
1824 |
apply (auto simp add: real_of_nat_Suc left_distrib)
|
paulson@15077
|
1825 |
done
|
paulson@15077
|
1826 |
|
paulson@15077
|
1827 |
lemma sin_npi2 [simp]: "sin (pi * real (n::nat)) = 0"
|
paulson@15383
|
1828 |
by (simp add: mult_commute [of pi])
|
paulson@15077
|
1829 |
|
paulson@15077
|
1830 |
lemma cos_two_pi [simp]: "cos (2 * pi) = 1"
|
paulson@15077
|
1831 |
by (simp add: cos_double)
|
paulson@15077
|
1832 |
|
paulson@15077
|
1833 |
lemma sin_two_pi [simp]: "sin (2 * pi) = 0"
|
paulson@15229
|
1834 |
by simp
|
paulson@15077
|
1835 |
|
paulson@15077
|
1836 |
lemma sin_gt_zero2: "[| 0 < x; x < pi/2 |] ==> 0 < sin x"
|
paulson@15077
|
1837 |
apply (rule sin_gt_zero, assumption)
|
paulson@15077
|
1838 |
apply (rule order_less_trans, assumption)
|
paulson@15077
|
1839 |
apply (rule pi_half_less_two)
|
paulson@15077
|
1840 |
done
|
paulson@15077
|
1841 |
|
paulson@15077
|
1842 |
lemma sin_less_zero:
|
paulson@15077
|
1843 |
assumes lb: "- pi/2 < x" and "x < 0" shows "sin x < 0"
|
paulson@15077
|
1844 |
proof -
|
paulson@15077
|
1845 |
have "0 < sin (- x)" using prems by (simp only: sin_gt_zero2)
|
paulson@15077
|
1846 |
thus ?thesis by simp
|
paulson@15077
|
1847 |
qed
|
paulson@15077
|
1848 |
|
paulson@15077
|
1849 |
lemma pi_less_4: "pi < 4"
|
paulson@15077
|
1850 |
by (cut_tac pi_half_less_two, auto)
|
paulson@15077
|
1851 |
|
paulson@15077
|
1852 |
lemma cos_gt_zero: "[| 0 < x; x < pi/2 |] ==> 0 < cos x"
|
paulson@15077
|
1853 |
apply (cut_tac pi_less_4)
|
paulson@15077
|
1854 |
apply (cut_tac f = cos and a = 0 and b = x and y = 0 in IVT2_objl, safe, simp_all)
|
paulson@15077
|
1855 |
apply (cut_tac cos_is_zero, safe)
|
paulson@15077
|
1856 |
apply (rename_tac y z)
|
paulson@15077
|
1857 |
apply (drule_tac x = y in spec)
|
paulson@15077
|
1858 |
apply (drule_tac x = "pi/2" in spec, simp)
|
paulson@15077
|
1859 |
done
|
paulson@15077
|
1860 |
|
paulson@15077
|
1861 |
lemma cos_gt_zero_pi: "[| -(pi/2) < x; x < pi/2 |] ==> 0 < cos x"
|
paulson@15077
|
1862 |
apply (rule_tac x = x and y = 0 in linorder_cases)
|
paulson@15077
|
1863 |
apply (rule cos_minus [THEN subst])
|
paulson@15077
|
1864 |
apply (rule cos_gt_zero)
|
paulson@15077
|
1865 |
apply (auto intro: cos_gt_zero)
|
paulson@15077
|
1866 |
done
|
paulson@15077
|
1867 |
|
paulson@15077
|
1868 |
lemma cos_ge_zero: "[| -(pi/2) \<le> x; x \<le> pi/2 |] ==> 0 \<le> cos x"
|
paulson@15077
|
1869 |
apply (auto simp add: order_le_less cos_gt_zero_pi)
|
paulson@15077
|
1870 |
apply (subgoal_tac "x = pi/2", auto)
|
paulson@15077
|
1871 |
done
|
paulson@15077
|
1872 |
|
paulson@15077
|
1873 |
lemma sin_gt_zero_pi: "[| 0 < x; x < pi |] ==> 0 < sin x"
|
paulson@15077
|
1874 |
apply (subst sin_cos_eq)
|
paulson@15077
|
1875 |
apply (rotate_tac 1)
|
paulson@15077
|
1876 |
apply (drule real_sum_of_halves [THEN ssubst])
|
paulson@15077
|
1877 |
apply (auto intro!: cos_gt_zero_pi simp del: sin_cos_eq [symmetric])
|
paulson@15077
|
1878 |
done
|
paulson@15077
|
1879 |
|
hoelzl@29740
|
1880 |
|
hoelzl@29740
|
1881 |
lemma pi_ge_two: "2 \<le> pi"
|
hoelzl@29740
|
1882 |
proof (rule ccontr)
|
hoelzl@29740
|
1883 |
assume "\<not> 2 \<le> pi" hence "pi < 2" by auto
|
hoelzl@29740
|
1884 |
have "\<exists>y > pi. y < 2 \<and> y < 2 * pi"
|
hoelzl@29740
|
1885 |
proof (cases "2 < 2 * pi")
|
hoelzl@29740
|
1886 |
case True with dense[OF `pi < 2`] show ?thesis by auto
|
hoelzl@29740
|
1887 |
next
|
hoelzl@29740
|
1888 |
case False have "pi < 2 * pi" by auto
|
hoelzl@29740
|
1889 |
from dense[OF this] and False show ?thesis by auto
|
hoelzl@29740
|
1890 |
qed
|
hoelzl@29740
|
1891 |
then obtain y where "pi < y" and "y < 2" and "y < 2 * pi" by blast
|
hoelzl@29740
|
1892 |
hence "0 < sin y" using sin_gt_zero by auto
|
hoelzl@29740
|
1893 |
moreover
|
hoelzl@29740
|
1894 |
have "sin y < 0" using sin_gt_zero_pi[of "y - pi"] `pi < y` and `y < 2 * pi` sin_periodic_pi[of "y - pi"] by auto
|
hoelzl@29740
|
1895 |
ultimately show False by auto
|
hoelzl@29740
|
1896 |
qed
|
hoelzl@29740
|
1897 |
|
paulson@15077
|
1898 |
lemma sin_ge_zero: "[| 0 \<le> x; x \<le> pi |] ==> 0 \<le> sin x"
|
paulson@15077
|
1899 |
by (auto simp add: order_le_less sin_gt_zero_pi)
|
paulson@15077
|
1900 |
|
paulson@15077
|
1901 |
lemma cos_total: "[| -1 \<le> y; y \<le> 1 |] ==> EX! x. 0 \<le> x & x \<le> pi & (cos x = y)"
|
paulson@15077
|
1902 |
apply (subgoal_tac "\<exists>x. 0 \<le> x & x \<le> pi & cos x = y")
|
paulson@15077
|
1903 |
apply (rule_tac [2] IVT2)
|
paulson@15077
|
1904 |
apply (auto intro: order_less_imp_le DERIV_isCont DERIV_cos)
|
paulson@15077
|
1905 |
apply (cut_tac x = xa and y = y in linorder_less_linear)
|
paulson@15077
|
1906 |
apply (rule ccontr, auto)
|
paulson@15077
|
1907 |
apply (drule_tac f = cos in Rolle)
|
paulson@15077
|
1908 |
apply (drule_tac [5] f = cos in Rolle)
|
paulson@15077
|
1909 |
apply (auto intro: order_less_imp_le DERIV_isCont DERIV_cos
|
paulson@15077
|
1910 |
dest!: DERIV_cos [THEN DERIV_unique]
|
paulson@15077
|
1911 |
simp add: differentiable_def)
|
paulson@15077
|
1912 |
apply (auto dest: sin_gt_zero_pi [OF order_le_less_trans order_less_le_trans])
|
paulson@15077
|
1913 |
done
|
paulson@15077
|
1914 |
|
paulson@15077
|
1915 |
lemma sin_total:
|
paulson@15077
|
1916 |
"[| -1 \<le> y; y \<le> 1 |] ==> EX! x. -(pi/2) \<le> x & x \<le> pi/2 & (sin x = y)"
|
paulson@15077
|
1917 |
apply (rule ccontr)
|
paulson@15077
|
1918 |
apply (subgoal_tac "\<forall>x. (- (pi/2) \<le> x & x \<le> pi/2 & (sin x = y)) = (0 \<le> (x + pi/2) & (x + pi/2) \<le> pi & (cos (x + pi/2) = -y))")
|
wenzelm@18585
|
1919 |
apply (erule contrapos_np)
|
paulson@15077
|
1920 |
apply (simp del: minus_sin_cos_eq [symmetric])
|
paulson@15077
|
1921 |
apply (cut_tac y="-y" in cos_total, simp) apply simp
|
paulson@15077
|
1922 |
apply (erule ex1E)
|
paulson@15229
|
1923 |
apply (rule_tac a = "x - (pi/2)" in ex1I)
|
huffman@23286
|
1924 |
apply (simp (no_asm) add: add_assoc)
|
paulson@15077
|
1925 |
apply (rotate_tac 3)
|
paulson@15077
|
1926 |
apply (drule_tac x = "xa + pi/2" in spec, safe, simp_all)
|
paulson@15077
|
1927 |
done
|
paulson@15077
|
1928 |
|
paulson@15077
|
1929 |
lemma reals_Archimedean4:
|
paulson@15077
|
1930 |
"[| 0 < y; 0 \<le> x |] ==> \<exists>n. real n * y \<le> x & x < real (Suc n) * y"
|
paulson@15077
|
1931 |
apply (auto dest!: reals_Archimedean3)
|
paulson@15077
|
1932 |
apply (drule_tac x = x in spec, clarify)
|
paulson@15077
|
1933 |
apply (subgoal_tac "x < real(LEAST m::nat. x < real m * y) * y")
|
paulson@15077
|
1934 |
prefer 2 apply (erule LeastI)
|
paulson@15077
|
1935 |
apply (case_tac "LEAST m::nat. x < real m * y", simp)
|
paulson@15077
|
1936 |
apply (subgoal_tac "~ x < real nat * y")
|
paulson@15077
|
1937 |
prefer 2 apply (rule not_less_Least, simp, force)
|
paulson@15077
|
1938 |
done
|
paulson@15077
|
1939 |
|
paulson@15077
|
1940 |
(* Pre Isabelle99-2 proof was simpler- numerals arithmetic
|
paulson@15077
|
1941 |
now causes some unwanted re-arrangements of literals! *)
|
paulson@15229
|
1942 |
lemma cos_zero_lemma:
|
paulson@15229
|
1943 |
"[| 0 \<le> x; cos x = 0 |] ==>
|
paulson@15077
|
1944 |
\<exists>n::nat. ~even n & x = real n * (pi/2)"
|
paulson@15077
|
1945 |
apply (drule pi_gt_zero [THEN reals_Archimedean4], safe)
|
paulson@15086
|
1946 |
apply (subgoal_tac "0 \<le> x - real n * pi &
|
paulson@15086
|
1947 |
(x - real n * pi) \<le> pi & (cos (x - real n * pi) = 0) ")
|
nipkow@29667
|
1948 |
apply (auto simp add: algebra_simps real_of_nat_Suc)
|
nipkow@29667
|
1949 |
prefer 2 apply (simp add: cos_diff)
|
paulson@15077
|
1950 |
apply (simp add: cos_diff)
|
paulson@15077
|
1951 |
apply (subgoal_tac "EX! x. 0 \<le> x & x \<le> pi & cos x = 0")
|
paulson@15077
|
1952 |
apply (rule_tac [2] cos_total, safe)
|
paulson@15077
|
1953 |
apply (drule_tac x = "x - real n * pi" in spec)
|
paulson@15077
|
1954 |
apply (drule_tac x = "pi/2" in spec)
|
paulson@15077
|
1955 |
apply (simp add: cos_diff)
|
paulson@15229
|
1956 |
apply (rule_tac x = "Suc (2 * n)" in exI)
|
nipkow@29667
|
1957 |
apply (simp add: real_of_nat_Suc algebra_simps, auto)
|
paulson@15077
|
1958 |
done
|
paulson@15077
|
1959 |
|
paulson@15229
|
1960 |
lemma sin_zero_lemma:
|
paulson@15229
|
1961 |
"[| 0 \<le> x; sin x = 0 |] ==>
|
paulson@15077
|
1962 |
\<exists>n::nat. even n & x = real n * (pi/2)"
|
paulson@15077
|
1963 |
apply (subgoal_tac "\<exists>n::nat. ~ even n & x + pi/2 = real n * (pi/2) ")
|
paulson@15077
|
1964 |
apply (clarify, rule_tac x = "n - 1" in exI)
|
paulson@15077
|
1965 |
apply (force simp add: odd_Suc_mult_two_ex real_of_nat_Suc left_distrib)
|
paulson@15085
|
1966 |
apply (rule cos_zero_lemma)
|
paulson@15085
|
1967 |
apply (simp_all add: add_increasing)
|
paulson@15077
|
1968 |
done
|
paulson@15077
|
1969 |
|
paulson@15077
|
1970 |
|
paulson@15229
|
1971 |
lemma cos_zero_iff:
|
paulson@15229
|
1972 |
"(cos x = 0) =
|
paulson@15077
|
1973 |
((\<exists>n::nat. ~even n & (x = real n * (pi/2))) |
|
paulson@15077
|
1974 |
(\<exists>n::nat. ~even n & (x = -(real n * (pi/2)))))"
|
paulson@15077
|
1975 |
apply (rule iffI)
|
paulson@15077
|
1976 |
apply (cut_tac linorder_linear [of 0 x], safe)
|
paulson@15077
|
1977 |
apply (drule cos_zero_lemma, assumption+)
|
paulson@15077
|
1978 |
apply (cut_tac x="-x" in cos_zero_lemma, simp, simp)
|
paulson@15077
|
1979 |
apply (force simp add: minus_equation_iff [of x])
|
paulson@15077
|
1980 |
apply (auto simp only: odd_Suc_mult_two_ex real_of_nat_Suc left_distrib)
|
nipkow@15539
|
1981 |
apply (auto simp add: cos_add)
|
paulson@15077
|
1982 |
done
|
paulson@15077
|
1983 |
|
paulson@15077
|
1984 |
(* ditto: but to a lesser extent *)
|
paulson@15229
|
1985 |
lemma sin_zero_iff:
|
paulson@15229
|
1986 |
"(sin x = 0) =
|
paulson@15077
|
1987 |
((\<exists>n::nat. even n & (x = real n * (pi/2))) |
|
paulson@15077
|
1988 |
(\<exists>n::nat. even n & (x = -(real n * (pi/2)))))"
|
paulson@15077
|
1989 |
apply (rule iffI)
|
paulson@15077
|
1990 |
apply (cut_tac linorder_linear [of 0 x], safe)
|
paulson@15077
|
1991 |
apply (drule sin_zero_lemma, assumption+)
|
paulson@15077
|
1992 |
apply (cut_tac x="-x" in sin_zero_lemma, simp, simp, safe)
|
paulson@15077
|
1993 |
apply (force simp add: minus_equation_iff [of x])
|
nipkow@15539
|
1994 |
apply (auto simp add: even_mult_two_ex)
|
paulson@15077
|
1995 |
done
|
paulson@15077
|
1996 |
|
hoelzl@29740
|
1997 |
lemma cos_monotone_0_pi: assumes "0 \<le> y" and "y < x" and "x \<le> pi"
|
hoelzl@29740
|
1998 |
shows "cos x < cos y"
|
hoelzl@29740
|
1999 |
proof -
|
hoelzl@29740
|
2000 |
have "- (x - y) < 0" by (auto!)
|
hoelzl@29740
|
2001 |
|
hoelzl@29740
|
2002 |
from MVT2[OF `y < x` DERIV_cos[THEN impI, THEN allI]]
|
hoelzl@29740
|
2003 |
obtain z where "y < z" and "z < x" and cos_diff: "cos x - cos y = (x - y) * - sin z" by auto
|
hoelzl@29740
|
2004 |
hence "0 < z" and "z < pi" by (auto!)
|
hoelzl@29740
|
2005 |
hence "0 < sin z" using sin_gt_zero_pi by auto
|
hoelzl@29740
|
2006 |
hence "cos x - cos y < 0" unfolding cos_diff minus_mult_commute[symmetric] using `- (x - y) < 0` by (rule mult_pos_neg2)
|
hoelzl@29740
|
2007 |
thus ?thesis by auto
|
hoelzl@29740
|
2008 |
qed
|
hoelzl@29740
|
2009 |
|
hoelzl@29740
|
2010 |
lemma cos_monotone_0_pi': assumes "0 \<le> y" and "y \<le> x" and "x \<le> pi" shows "cos x \<le> cos y"
|
hoelzl@29740
|
2011 |
proof (cases "y < x")
|
hoelzl@29740
|
2012 |
case True show ?thesis using cos_monotone_0_pi[OF `0 \<le> y` True `x \<le> pi`] by auto
|
hoelzl@29740
|
2013 |
next
|
hoelzl@29740
|
2014 |
case False hence "y = x" using `y \<le> x` by auto
|
hoelzl@29740
|
2015 |
thus ?thesis by auto
|
hoelzl@29740
|
2016 |
qed
|
hoelzl@29740
|
2017 |
|
hoelzl@29740
|
2018 |
lemma cos_monotone_minus_pi_0: assumes "-pi \<le> y" and "y < x" and "x \<le> 0"
|
hoelzl@29740
|
2019 |
shows "cos y < cos x"
|
hoelzl@29740
|
2020 |
proof -
|
hoelzl@29740
|
2021 |
have "0 \<le> -x" and "-x < -y" and "-y \<le> pi" by (auto!)
|
hoelzl@29740
|
2022 |
from cos_monotone_0_pi[OF this]
|
hoelzl@29740
|
2023 |
show ?thesis unfolding cos_minus .
|
hoelzl@29740
|
2024 |
qed
|
hoelzl@29740
|
2025 |
|
hoelzl@29740
|
2026 |
lemma cos_monotone_minus_pi_0': assumes "-pi \<le> y" and "y \<le> x" and "x \<le> 0" shows "cos y \<le> cos x"
|
hoelzl@29740
|
2027 |
proof (cases "y < x")
|
hoelzl@29740
|
2028 |
case True show ?thesis using cos_monotone_minus_pi_0[OF `-pi \<le> y` True `x \<le> 0`] by auto
|
hoelzl@29740
|
2029 |
next
|
hoelzl@29740
|
2030 |
case False hence "y = x" using `y \<le> x` by auto
|
hoelzl@29740
|
2031 |
thus ?thesis by auto
|
hoelzl@29740
|
2032 |
qed
|
hoelzl@29740
|
2033 |
|
hoelzl@29740
|
2034 |
lemma sin_monotone_2pi': assumes "- (pi / 2) \<le> y" and "y \<le> x" and "x \<le> pi / 2" shows "sin y \<le> sin x"
|
hoelzl@29740
|
2035 |
proof -
|
hoelzl@29740
|
2036 |
have "0 \<le> y + pi / 2" and "y + pi / 2 \<le> x + pi / 2" and "x + pi /2 \<le> pi" using pi_ge_two by (auto!)
|
hoelzl@29740
|
2037 |
from cos_monotone_0_pi'[OF this] show ?thesis unfolding minus_sin_cos_eq[symmetric] by auto
|
hoelzl@29740
|
2038 |
qed
|
paulson@15077
|
2039 |
|
huffman@29164
|
2040 |
subsection {* Tangent *}
|
paulson@15077
|
2041 |
|
huffman@23043
|
2042 |
definition
|
huffman@23043
|
2043 |
tan :: "real => real" where
|
huffman@23043
|
2044 |
"tan x = (sin x)/(cos x)"
|
huffman@23043
|
2045 |
|
paulson@15077
|
2046 |
lemma tan_zero [simp]: "tan 0 = 0"
|
paulson@15077
|
2047 |
by (simp add: tan_def)
|
paulson@15077
|
2048 |
|
paulson@15077
|
2049 |
lemma tan_pi [simp]: "tan pi = 0"
|
paulson@15077
|
2050 |
by (simp add: tan_def)
|
paulson@15077
|
2051 |
|
paulson@15077
|
2052 |
lemma tan_npi [simp]: "tan (real (n::nat) * pi) = 0"
|
paulson@15077
|
2053 |
by (simp add: tan_def)
|
paulson@15077
|
2054 |
|
paulson@15077
|
2055 |
lemma tan_minus [simp]: "tan (-x) = - tan x"
|
paulson@15077
|
2056 |
by (simp add: tan_def minus_mult_left)
|
paulson@15077
|
2057 |
|
paulson@15077
|
2058 |
lemma tan_periodic [simp]: "tan (x + 2*pi) = tan x"
|
paulson@15077
|
2059 |
by (simp add: tan_def)
|
paulson@15077
|
2060 |
|
paulson@15077
|
2061 |
lemma lemma_tan_add1:
|
paulson@15077
|
2062 |
"[| cos x \<noteq> 0; cos y \<noteq> 0 |]
|
paulson@15077
|
2063 |
==> 1 - tan(x)*tan(y) = cos (x + y)/(cos x * cos y)"
|
paulson@15229
|
2064 |
apply (simp add: tan_def divide_inverse)
|
paulson@15229
|
2065 |
apply (auto simp del: inverse_mult_distrib
|
paulson@15229
|
2066 |
simp add: inverse_mult_distrib [symmetric] mult_ac)
|
paulson@15077
|
2067 |
apply (rule_tac c1 = "cos x * cos y" in real_mult_right_cancel [THEN subst])
|
paulson@15229
|
2068 |
apply (auto simp del: inverse_mult_distrib
|
paulson@15229
|
2069 |
simp add: mult_assoc left_diff_distrib cos_add)
|
nipkow@29667
|
2070 |
done
|
paulson@15077
|
2071 |
|
paulson@15077
|
2072 |
lemma add_tan_eq:
|
paulson@15077
|
2073 |
"[| cos x \<noteq> 0; cos y \<noteq> 0 |]
|
paulson@15077
|
2074 |
==> tan x + tan y = sin(x + y)/(cos x * cos y)"
|
paulson@15229
|
2075 |
apply (simp add: tan_def)
|
paulson@15077
|
2076 |
apply (rule_tac c1 = "cos x * cos y" in real_mult_right_cancel [THEN subst])
|
paulson@15077
|
2077 |
apply (auto simp add: mult_assoc left_distrib)
|
nipkow@15539
|
2078 |
apply (simp add: sin_add)
|
paulson@15077
|
2079 |
done
|
paulson@15077
|
2080 |
|
paulson@15229
|
2081 |
lemma tan_add:
|
paulson@15229
|
2082 |
"[| cos x \<noteq> 0; cos y \<noteq> 0; cos (x + y) \<noteq> 0 |]
|
paulson@15077
|
2083 |
==> tan(x + y) = (tan(x) + tan(y))/(1 - tan(x) * tan(y))"
|
paulson@15077
|
2084 |
apply (simp (no_asm_simp) add: add_tan_eq lemma_tan_add1)
|
paulson@15077
|
2085 |
apply (simp add: tan_def)
|
paulson@15077
|
2086 |
done
|
paulson@15077
|
2087 |
|
paulson@15229
|
2088 |
lemma tan_double:
|
paulson@15229
|
2089 |
"[| cos x \<noteq> 0; cos (2 * x) \<noteq> 0 |]
|
paulson@15077
|
2090 |
==> tan (2 * x) = (2 * tan x)/(1 - (tan(x) ^ 2))"
|
paulson@15077
|
2091 |
apply (insert tan_add [of x x])
|
paulson@15077
|
2092 |
apply (simp add: mult_2 [symmetric])
|
paulson@15077
|
2093 |
apply (auto simp add: numeral_2_eq_2)
|
paulson@15077
|
2094 |
done
|
paulson@15077
|
2095 |
|
paulson@15077
|
2096 |
lemma tan_gt_zero: "[| 0 < x; x < pi/2 |] ==> 0 < tan x"
|
paulson@15229
|
2097 |
by (simp add: tan_def zero_less_divide_iff sin_gt_zero2 cos_gt_zero_pi)
|
paulson@15077
|
2098 |
|
paulson@15077
|
2099 |
lemma tan_less_zero:
|
paulson@15077
|
2100 |
assumes lb: "- pi/2 < x" and "x < 0" shows "tan x < 0"
|
paulson@15077
|
2101 |
proof -
|
paulson@15077
|
2102 |
have "0 < tan (- x)" using prems by (simp only: tan_gt_zero)
|
paulson@15077
|
2103 |
thus ?thesis by simp
|
paulson@15077
|
2104 |
qed
|
paulson@15077
|
2105 |
|
hoelzl@29740
|
2106 |
lemma tan_half: fixes x :: real assumes "- (pi / 2) < x" and "x < pi / 2"
|
hoelzl@29740
|
2107 |
shows "tan x = sin (2 * x) / (cos (2 * x) + 1)"
|
hoelzl@29740
|
2108 |
proof -
|
hoelzl@29740
|
2109 |
from cos_gt_zero_pi[OF `- (pi / 2) < x` `x < pi / 2`]
|
hoelzl@29740
|
2110 |
have "cos x \<noteq> 0" by auto
|
hoelzl@29740
|
2111 |
|
hoelzl@29740
|
2112 |
have minus_cos_2x: "\<And>X. X - cos (2*x) = X - (cos x) ^ 2 + (sin x) ^ 2" unfolding cos_double by algebra
|
hoelzl@29740
|
2113 |
|
hoelzl@29740
|
2114 |
have "tan x = (tan x + tan x) / 2" by auto
|
hoelzl@29740
|
2115 |
also have "\<dots> = sin (x + x) / (cos x * cos x) / 2" unfolding add_tan_eq[OF `cos x \<noteq> 0` `cos x \<noteq> 0`] ..
|
hoelzl@29740
|
2116 |
also have "\<dots> = sin (2 * x) / ((cos x) ^ 2 + (cos x) ^ 2 + cos (2*x) - cos (2*x))" unfolding divide_divide_eq_left numeral_2_eq_2 by auto
|
hoelzl@29740
|
2117 |
also have "\<dots> = sin (2 * x) / ((cos x) ^ 2 + cos (2*x) + (sin x)^2)" unfolding minus_cos_2x by auto
|
hoelzl@29740
|
2118 |
also have "\<dots> = sin (2 * x) / (cos (2*x) + 1)" by auto
|
hoelzl@29740
|
2119 |
finally show ?thesis .
|
hoelzl@29740
|
2120 |
qed
|
hoelzl@29740
|
2121 |
|
paulson@15077
|
2122 |
lemma lemma_DERIV_tan:
|
paulson@15077
|
2123 |
"cos x \<noteq> 0 ==> DERIV (%x. sin(x)/cos(x)) x :> inverse((cos x)\<twosuperior>)"
|
paulson@15077
|
2124 |
apply (rule lemma_DERIV_subst)
|
paulson@15077
|
2125 |
apply (best intro!: DERIV_intros intro: DERIV_chain2)
|
paulson@15079
|
2126 |
apply (auto simp add: divide_inverse numeral_2_eq_2)
|
paulson@15077
|
2127 |
done
|
paulson@15077
|
2128 |
|
paulson@15077
|
2129 |
lemma DERIV_tan [simp]: "cos x \<noteq> 0 ==> DERIV tan x :> inverse((cos x)\<twosuperior>)"
|
paulson@15077
|
2130 |
by (auto dest: lemma_DERIV_tan simp add: tan_def [symmetric])
|
paulson@15077
|
2131 |
|
huffman@23045
|
2132 |
lemma isCont_tan [simp]: "cos x \<noteq> 0 ==> isCont tan x"
|
huffman@23045
|
2133 |
by (rule DERIV_tan [THEN DERIV_isCont])
|
huffman@23045
|
2134 |
|
paulson@15077
|
2135 |
lemma LIM_cos_div_sin [simp]: "(%x. cos(x)/sin(x)) -- pi/2 --> 0"
|
paulson@15077
|
2136 |
apply (subgoal_tac "(\<lambda>x. cos x * inverse (sin x)) -- pi * inverse 2 --> 0*1")
|
paulson@15229
|
2137 |
apply (simp add: divide_inverse [symmetric])
|
huffman@22613
|
2138 |
apply (rule LIM_mult)
|
paulson@15077
|
2139 |
apply (rule_tac [2] inverse_1 [THEN subst])
|
paulson@15077
|
2140 |
apply (rule_tac [2] LIM_inverse)
|
paulson@15077
|
2141 |
apply (simp_all add: divide_inverse [symmetric])
|
paulson@15077
|
2142 |
apply (simp_all only: isCont_def [symmetric] cos_pi_half [symmetric] sin_pi_half [symmetric])
|
paulson@15077
|
2143 |
apply (blast intro!: DERIV_isCont DERIV_sin DERIV_cos)+
|
paulson@15077
|
2144 |
done
|
paulson@15077
|
2145 |
|
paulson@15077
|
2146 |
lemma lemma_tan_total: "0 < y ==> \<exists>x. 0 < x & x < pi/2 & y < tan x"
|
paulson@15077
|
2147 |
apply (cut_tac LIM_cos_div_sin)
|
huffman@31325
|
2148 |
apply (simp only: LIM_eq)
|
paulson@15077
|
2149 |
apply (drule_tac x = "inverse y" in spec, safe, force)
|
paulson@15077
|
2150 |
apply (drule_tac ?d1.0 = s in pi_half_gt_zero [THEN [2] real_lbound_gt_zero], safe)
|
paulson@15229
|
2151 |
apply (rule_tac x = "(pi/2) - e" in exI)
|
paulson@15077
|
2152 |
apply (simp (no_asm_simp))
|
paulson@15229
|
2153 |
apply (drule_tac x = "(pi/2) - e" in spec)
|
paulson@15229
|
2154 |
apply (auto simp add: tan_def)
|
paulson@15077
|
2155 |
apply (rule inverse_less_iff_less [THEN iffD1])
|
paulson@15079
|
2156 |
apply (auto simp add: divide_inverse)
|
paulson@15229
|
2157 |
apply (rule real_mult_order)
|
paulson@15229
|
2158 |
apply (subgoal_tac [3] "0 < sin e & 0 < cos e")
|
paulson@15229
|
2159 |
apply (auto intro: cos_gt_zero sin_gt_zero2 simp add: mult_commute)
|
paulson@15077
|
2160 |
done
|
paulson@15077
|
2161 |
|
paulson@15077
|
2162 |
lemma tan_total_pos: "0 \<le> y ==> \<exists>x. 0 \<le> x & x < pi/2 & tan x = y"
|
huffman@22998
|
2163 |
apply (frule order_le_imp_less_or_eq, safe)
|
paulson@15077
|
2164 |
prefer 2 apply force
|
paulson@15077
|
2165 |
apply (drule lemma_tan_total, safe)
|
paulson@15077
|
2166 |
apply (cut_tac f = tan and a = 0 and b = x and y = y in IVT_objl)
|
paulson@15077
|
2167 |
apply (auto intro!: DERIV_tan [THEN DERIV_isCont])
|
paulson@15077
|
2168 |
apply (drule_tac y = xa in order_le_imp_less_or_eq)
|
paulson@15077
|
2169 |
apply (auto dest: cos_gt_zero)
|
paulson@15077
|
2170 |
done
|
paulson@15077
|
2171 |
|
paulson@15077
|
2172 |
lemma lemma_tan_total1: "\<exists>x. -(pi/2) < x & x < (pi/2) & tan x = y"
|
paulson@15077
|
2173 |
apply (cut_tac linorder_linear [of 0 y], safe)
|
paulson@15077
|
2174 |
apply (drule tan_total_pos)
|
paulson@15077
|
2175 |
apply (cut_tac [2] y="-y" in tan_total_pos, safe)
|
paulson@15077
|
2176 |
apply (rule_tac [3] x = "-x" in exI)
|
paulson@15077
|
2177 |
apply (auto intro!: exI)
|
paulson@15077
|
2178 |
done
|
paulson@15077
|
2179 |
|
paulson@15077
|
2180 |
lemma tan_total: "EX! x. -(pi/2) < x & x < (pi/2) & tan x = y"
|
paulson@15077
|
2181 |
apply (cut_tac y = y in lemma_tan_total1, auto)
|
paulson@15077
|
2182 |
apply (cut_tac x = xa and y = y in linorder_less_linear, auto)
|
paulson@15077
|
2183 |
apply (subgoal_tac [2] "\<exists>z. y < z & z < xa & DERIV tan z :> 0")
|
paulson@15077
|
2184 |
apply (subgoal_tac "\<exists>z. xa < z & z < y & DERIV tan z :> 0")
|
paulson@15077
|
2185 |
apply (rule_tac [4] Rolle)
|
paulson@15077
|
2186 |
apply (rule_tac [2] Rolle)
|
paulson@15077
|
2187 |
apply (auto intro!: DERIV_tan DERIV_isCont exI
|
paulson@15077
|
2188 |
simp add: differentiable_def)
|
paulson@15077
|
2189 |
txt{*Now, simulate TRYALL*}
|
paulson@15077
|
2190 |
apply (rule_tac [!] DERIV_tan asm_rl)
|
paulson@15077
|
2191 |
apply (auto dest!: DERIV_unique [OF _ DERIV_tan]
|
huffman@22998
|
2192 |
simp add: cos_gt_zero_pi [THEN less_imp_neq, THEN not_sym])
|
paulson@15077
|
2193 |
done
|
paulson@15077
|
2194 |
|
hoelzl@29740
|
2195 |
lemma tan_monotone: assumes "- (pi / 2) < y" and "y < x" and "x < pi / 2"
|
hoelzl@29740
|
2196 |
shows "tan y < tan x"
|
hoelzl@29740
|
2197 |
proof -
|
hoelzl@29740
|
2198 |
have "\<forall> x'. y \<le> x' \<and> x' \<le> x \<longrightarrow> DERIV tan x' :> inverse (cos x'^2)"
|
hoelzl@29740
|
2199 |
proof (rule allI, rule impI)
|
hoelzl@29740
|
2200 |
fix x' :: real assume "y \<le> x' \<and> x' \<le> x"
|
hoelzl@29740
|
2201 |
hence "-(pi/2) < x'" and "x' < pi/2" by (auto!)
|
hoelzl@29740
|
2202 |
from cos_gt_zero_pi[OF this]
|
hoelzl@29740
|
2203 |
have "cos x' \<noteq> 0" by auto
|
hoelzl@29740
|
2204 |
thus "DERIV tan x' :> inverse (cos x'^2)" by (rule DERIV_tan)
|
hoelzl@29740
|
2205 |
qed
|
hoelzl@29740
|
2206 |
from MVT2[OF `y < x` this]
|
hoelzl@29740
|
2207 |
obtain z where "y < z" and "z < x" and tan_diff: "tan x - tan y = (x - y) * inverse ((cos z)\<twosuperior>)" by auto
|
hoelzl@29740
|
2208 |
hence "- (pi / 2) < z" and "z < pi / 2" by (auto!)
|
hoelzl@29740
|
2209 |
hence "0 < cos z" using cos_gt_zero_pi by auto
|
hoelzl@29740
|
2210 |
hence inv_pos: "0 < inverse ((cos z)\<twosuperior>)" by auto
|
hoelzl@29740
|
2211 |
have "0 < x - y" using `y < x` by auto
|
hoelzl@29740
|
2212 |
from real_mult_order[OF this inv_pos]
|
hoelzl@29740
|
2213 |
have "0 < tan x - tan y" unfolding tan_diff by auto
|
hoelzl@29740
|
2214 |
thus ?thesis by auto
|
hoelzl@29740
|
2215 |
qed
|
hoelzl@29740
|
2216 |
|
hoelzl@29740
|
2217 |
lemma tan_monotone': assumes "- (pi / 2) < y" and "y < pi / 2" and "- (pi / 2) < x" and "x < pi / 2"
|
hoelzl@29740
|
2218 |
shows "(y < x) = (tan y < tan x)"
|
hoelzl@29740
|
2219 |
proof
|
hoelzl@29740
|
2220 |
assume "y < x" thus "tan y < tan x" using tan_monotone and `- (pi / 2) < y` and `x < pi / 2` by auto
|
hoelzl@29740
|
2221 |
next
|
hoelzl@29740
|
2222 |
assume "tan y < tan x"
|
hoelzl@29740
|
2223 |
show "y < x"
|
hoelzl@29740
|
2224 |
proof (rule ccontr)
|
hoelzl@29740
|
2225 |
assume "\<not> y < x" hence "x \<le> y" by auto
|
hoelzl@29740
|
2226 |
hence "tan x \<le> tan y"
|
hoelzl@29740
|
2227 |
proof (cases "x = y")
|
hoelzl@29740
|
2228 |
case True thus ?thesis by auto
|
hoelzl@29740
|
2229 |
next
|
hoelzl@29740
|
2230 |
case False hence "x < y" using `x \<le> y` by auto
|
hoelzl@29740
|
2231 |
from tan_monotone[OF `- (pi/2) < x` this `y < pi / 2`] show ?thesis by auto
|
hoelzl@29740
|
2232 |
qed
|
hoelzl@29740
|
2233 |
thus False using `tan y < tan x` by auto
|
hoelzl@29740
|
2234 |
qed
|
hoelzl@29740
|
2235 |
qed
|
hoelzl@29740
|
2236 |
|
hoelzl@29740
|
2237 |
lemma tan_inverse: "1 / (tan y) = tan (pi / 2 - y)" unfolding tan_def sin_cos_eq[of y] cos_sin_eq[of y] by auto
|
hoelzl@29740
|
2238 |
|
hoelzl@29740
|
2239 |
lemma tan_periodic_pi[simp]: "tan (x + pi) = tan x"
|
hoelzl@29740
|
2240 |
by (simp add: tan_def)
|
hoelzl@29740
|
2241 |
|
hoelzl@29740
|
2242 |
lemma tan_periodic_nat[simp]: fixes n :: nat shows "tan (x + real n * pi) = tan x"
|
hoelzl@29740
|
2243 |
proof (induct n arbitrary: x)
|
hoelzl@29740
|
2244 |
case (Suc n)
|
nipkow@31790
|
2245 |
have split_pi_off: "x + real (Suc n) * pi = (x + real n * pi) + pi" unfolding Suc_eq_plus1 real_of_nat_add real_of_one real_add_mult_distrib by auto
|
hoelzl@29740
|
2246 |
show ?case unfolding split_pi_off using Suc by auto
|
hoelzl@29740
|
2247 |
qed auto
|
hoelzl@29740
|
2248 |
|
hoelzl@29740
|
2249 |
lemma tan_periodic_int[simp]: fixes i :: int shows "tan (x + real i * pi) = tan x"
|
hoelzl@29740
|
2250 |
proof (cases "0 \<le> i")
|
hoelzl@29740
|
2251 |
case True hence i_nat: "real i = real (nat i)" by auto
|
hoelzl@29740
|
2252 |
show ?thesis unfolding i_nat by auto
|
hoelzl@29740
|
2253 |
next
|
hoelzl@29740
|
2254 |
case False hence i_nat: "real i = - real (nat (-i))" by auto
|
hoelzl@29740
|
2255 |
have "tan x = tan (x + real i * pi - real i * pi)" by auto
|
hoelzl@29740
|
2256 |
also have "\<dots> = tan (x + real i * pi)" unfolding i_nat mult_minus_left diff_minus_eq_add by (rule tan_periodic_nat)
|
hoelzl@29740
|
2257 |
finally show ?thesis by auto
|
hoelzl@29740
|
2258 |
qed
|
hoelzl@29740
|
2259 |
|
hoelzl@29740
|
2260 |
lemma tan_periodic_n[simp]: "tan (x + number_of n * pi) = tan x"
|
hoelzl@29740
|
2261 |
using tan_periodic_int[of _ "number_of n" ] unfolding real_number_of .
|
huffman@23043
|
2262 |
|
huffman@23043
|
2263 |
subsection {* Inverse Trigonometric Functions *}
|
huffman@23043
|
2264 |
|
huffman@23043
|
2265 |
definition
|
huffman@23043
|
2266 |
arcsin :: "real => real" where
|
huffman@23043
|
2267 |
"arcsin y = (THE x. -(pi/2) \<le> x & x \<le> pi/2 & sin x = y)"
|
huffman@23043
|
2268 |
|
huffman@23043
|
2269 |
definition
|
huffman@23043
|
2270 |
arccos :: "real => real" where
|
huffman@23043
|
2271 |
"arccos y = (THE x. 0 \<le> x & x \<le> pi & cos x = y)"
|
huffman@23043
|
2272 |
|
huffman@23043
|
2273 |
definition
|
huffman@23043
|
2274 |
arctan :: "real => real" where
|
huffman@23043
|
2275 |
"arctan y = (THE x. -(pi/2) < x & x < pi/2 & tan x = y)"
|
huffman@23043
|
2276 |
|
paulson@15229
|
2277 |
lemma arcsin:
|
paulson@15229
|
2278 |
"[| -1 \<le> y; y \<le> 1 |]
|
paulson@15077
|
2279 |
==> -(pi/2) \<le> arcsin y &
|
paulson@15077
|
2280 |
arcsin y \<le> pi/2 & sin(arcsin y) = y"
|
huffman@23011
|
2281 |
unfolding arcsin_def by (rule theI' [OF sin_total])
|
huffman@23011
|
2282 |
|
huffman@23011
|
2283 |
lemma arcsin_pi:
|
huffman@23011
|
2284 |
"[| -1 \<le> y; y \<le> 1 |]
|
huffman@23011
|
2285 |
==> -(pi/2) \<le> arcsin y & arcsin y \<le> pi & sin(arcsin y) = y"
|
huffman@23011
|
2286 |
apply (drule (1) arcsin)
|
huffman@23011
|
2287 |
apply (force intro: order_trans)
|
paulson@15077
|
2288 |
done
|
paulson@15077
|
2289 |
|
paulson@15077
|
2290 |
lemma sin_arcsin [simp]: "[| -1 \<le> y; y \<le> 1 |] ==> sin(arcsin y) = y"
|
paulson@15077
|
2291 |
by (blast dest: arcsin)
|
paulson@15077
|
2292 |
|
paulson@15077
|
2293 |
lemma arcsin_bounded:
|
paulson@15077
|
2294 |
"[| -1 \<le> y; y \<le> 1 |] ==> -(pi/2) \<le> arcsin y & arcsin y \<le> pi/2"
|
paulson@15077
|
2295 |
by (blast dest: arcsin)
|
paulson@15077
|
2296 |
|
paulson@15077
|
2297 |
lemma arcsin_lbound: "[| -1 \<le> y; y \<le> 1 |] ==> -(pi/2) \<le> arcsin y"
|
paulson@15077
|
2298 |
by (blast dest: arcsin)
|
paulson@15077
|
2299 |
|
paulson@15077
|
2300 |
lemma arcsin_ubound: "[| -1 \<le> y; y \<le> 1 |] ==> arcsin y \<le> pi/2"
|
paulson@15077
|
2301 |
by (blast dest: arcsin)
|
paulson@15077
|
2302 |
|
paulson@15077
|
2303 |
lemma arcsin_lt_bounded:
|
paulson@15077
|
2304 |
"[| -1 < y; y < 1 |] ==> -(pi/2) < arcsin y & arcsin y < pi/2"
|
paulson@15077
|
2305 |
apply (frule order_less_imp_le)
|
paulson@15077
|
2306 |
apply (frule_tac y = y in order_less_imp_le)
|
paulson@15077
|
2307 |
apply (frule arcsin_bounded)
|
paulson@15077
|
2308 |
apply (safe, simp)
|
paulson@15077
|
2309 |
apply (drule_tac y = "arcsin y" in order_le_imp_less_or_eq)
|
paulson@15077
|
2310 |
apply (drule_tac [2] y = "pi/2" in order_le_imp_less_or_eq, safe)
|
paulson@15077
|
2311 |
apply (drule_tac [!] f = sin in arg_cong, auto)
|
paulson@15077
|
2312 |
done
|
paulson@15077
|
2313 |
|
paulson@15077
|
2314 |
lemma arcsin_sin: "[|-(pi/2) \<le> x; x \<le> pi/2 |] ==> arcsin(sin x) = x"
|
paulson@15077
|
2315 |
apply (unfold arcsin_def)
|
huffman@23011
|
2316 |
apply (rule the1_equality)
|
paulson@15077
|
2317 |
apply (rule sin_total, auto)
|
paulson@15077
|
2318 |
done
|
paulson@15077
|
2319 |
|
huffman@22975
|
2320 |
lemma arccos:
|
paulson@15229
|
2321 |
"[| -1 \<le> y; y \<le> 1 |]
|
huffman@22975
|
2322 |
==> 0 \<le> arccos y & arccos y \<le> pi & cos(arccos y) = y"
|
huffman@23011
|
2323 |
unfolding arccos_def by (rule theI' [OF cos_total])
|
paulson@15077
|
2324 |
|
huffman@22975
|
2325 |
lemma cos_arccos [simp]: "[| -1 \<le> y; y \<le> 1 |] ==> cos(arccos y) = y"
|
huffman@22975
|
2326 |
by (blast dest: arccos)
|
paulson@15077
|
2327 |
|
huffman@22975
|
2328 |
lemma arccos_bounded: "[| -1 \<le> y; y \<le> 1 |] ==> 0 \<le> arccos y & arccos y \<le> pi"
|
huffman@22975
|
2329 |
by (blast dest: arccos)
|
paulson@15077
|
2330 |
|
huffman@22975
|
2331 |
lemma arccos_lbound: "[| -1 \<le> y; y \<le> 1 |] ==> 0 \<le> arccos y"
|
huffman@22975
|
2332 |
by (blast dest: arccos)
|
paulson@15077
|
2333 |
|
huffman@22975
|
2334 |
lemma arccos_ubound: "[| -1 \<le> y; y \<le> 1 |] ==> arccos y \<le> pi"
|
huffman@22975
|
2335 |
by (blast dest: arccos)
|
paulson@15077
|
2336 |
|
huffman@22975
|
2337 |
lemma arccos_lt_bounded:
|
paulson@15229
|
2338 |
"[| -1 < y; y < 1 |]
|
huffman@22975
|
2339 |
==> 0 < arccos y & arccos y < pi"
|
paulson@15077
|
2340 |
apply (frule order_less_imp_le)
|
paulson@15077
|
2341 |
apply (frule_tac y = y in order_less_imp_le)
|
huffman@22975
|
2342 |
apply (frule arccos_bounded, auto)
|
huffman@22975
|
2343 |
apply (drule_tac y = "arccos y" in order_le_imp_less_or_eq)
|
paulson@15077
|
2344 |
apply (drule_tac [2] y = pi in order_le_imp_less_or_eq, auto)
|
paulson@15077
|
2345 |
apply (drule_tac [!] f = cos in arg_cong, auto)
|
paulson@15077
|
2346 |
done
|
paulson@15077
|
2347 |
|
huffman@22975
|
2348 |
lemma arccos_cos: "[|0 \<le> x; x \<le> pi |] ==> arccos(cos x) = x"
|
huffman@22975
|
2349 |
apply (simp add: arccos_def)
|
huffman@23011
|
2350 |
apply (auto intro!: the1_equality cos_total)
|
paulson@15077
|
2351 |
done
|
paulson@15077
|
2352 |
|
huffman@22975
|
2353 |
lemma arccos_cos2: "[|x \<le> 0; -pi \<le> x |] ==> arccos(cos x) = -x"
|
huffman@22975
|
2354 |
apply (simp add: arccos_def)
|
huffman@23011
|
2355 |
apply (auto intro!: the1_equality cos_total)
|
paulson@15077
|
2356 |
done
|
paulson@15077
|
2357 |
|
huffman@23045
|
2358 |
lemma cos_arcsin: "\<lbrakk>-1 \<le> x; x \<le> 1\<rbrakk> \<Longrightarrow> cos (arcsin x) = sqrt (1 - x\<twosuperior>)"
|
huffman@23045
|
2359 |
apply (subgoal_tac "x\<twosuperior> \<le> 1")
|
huffman@23052
|
2360 |
apply (rule power2_eq_imp_eq)
|
huffman@23045
|
2361 |
apply (simp add: cos_squared_eq)
|
huffman@23045
|
2362 |
apply (rule cos_ge_zero)
|
huffman@23045
|
2363 |
apply (erule (1) arcsin_lbound)
|
huffman@23045
|
2364 |
apply (erule (1) arcsin_ubound)
|
huffman@23045
|
2365 |
apply simp
|
huffman@23045
|
2366 |
apply (subgoal_tac "\<bar>x\<bar>\<twosuperior> \<le> 1\<twosuperior>", simp)
|
huffman@23045
|
2367 |
apply (rule power_mono, simp, simp)
|
huffman@23045
|
2368 |
done
|
huffman@23045
|
2369 |
|
huffman@23045
|
2370 |
lemma sin_arccos: "\<lbrakk>-1 \<le> x; x \<le> 1\<rbrakk> \<Longrightarrow> sin (arccos x) = sqrt (1 - x\<twosuperior>)"
|
huffman@23045
|
2371 |
apply (subgoal_tac "x\<twosuperior> \<le> 1")
|
huffman@23052
|
2372 |
apply (rule power2_eq_imp_eq)
|
huffman@23045
|
2373 |
apply (simp add: sin_squared_eq)
|
huffman@23045
|
2374 |
apply (rule sin_ge_zero)
|
huffman@23045
|
2375 |
apply (erule (1) arccos_lbound)
|
huffman@23045
|
2376 |
apply (erule (1) arccos_ubound)
|
huffman@23045
|
2377 |
apply simp
|
huffman@23045
|
2378 |
apply (subgoal_tac "\<bar>x\<bar>\<twosuperior> \<le> 1\<twosuperior>", simp)
|
huffman@23045
|
2379 |
apply (rule power_mono, simp, simp)
|
huffman@23045
|
2380 |
done
|
huffman@23045
|
2381 |
|
paulson@15077
|
2382 |
lemma arctan [simp]:
|
paulson@15077
|
2383 |
"- (pi/2) < arctan y & arctan y < pi/2 & tan (arctan y) = y"
|
huffman@23011
|
2384 |
unfolding arctan_def by (rule theI' [OF tan_total])
|
paulson@15077
|
2385 |
|
paulson@15077
|
2386 |
lemma tan_arctan: "tan(arctan y) = y"
|
paulson@15077
|
2387 |
by auto
|
paulson@15077
|
2388 |
|
paulson@15077
|
2389 |
lemma arctan_bounded: "- (pi/2) < arctan y & arctan y < pi/2"
|
paulson@15077
|
2390 |
by (auto simp only: arctan)
|
paulson@15077
|
2391 |
|
paulson@15077
|
2392 |
lemma arctan_lbound: "- (pi/2) < arctan y"
|
paulson@15077
|
2393 |
by auto
|
paulson@15077
|
2394 |
|
paulson@15077
|
2395 |
lemma arctan_ubound: "arctan y < pi/2"
|
paulson@15077
|
2396 |
by (auto simp only: arctan)
|
paulson@15077
|
2397 |
|
paulson@15077
|
2398 |
lemma arctan_tan:
|
paulson@15077
|
2399 |
"[|-(pi/2) < x; x < pi/2 |] ==> arctan(tan x) = x"
|
paulson@15077
|
2400 |
apply (unfold arctan_def)
|
huffman@23011
|
2401 |
apply (rule the1_equality)
|
paulson@15077
|
2402 |
apply (rule tan_total, auto)
|
paulson@15077
|
2403 |
done
|
paulson@15077
|
2404 |
|
paulson@15077
|
2405 |
lemma arctan_zero_zero [simp]: "arctan 0 = 0"
|
paulson@15077
|
2406 |
by (insert arctan_tan [of 0], simp)
|
paulson@15077
|
2407 |
|
paulson@15077
|
2408 |
lemma cos_arctan_not_zero [simp]: "cos(arctan x) \<noteq> 0"
|
paulson@15077
|
2409 |
apply (auto simp add: cos_zero_iff)
|
paulson@15077
|
2410 |
apply (case_tac "n")
|
paulson@15077
|
2411 |
apply (case_tac [3] "n")
|
paulson@15077
|
2412 |
apply (cut_tac [2] y = x in arctan_ubound)
|
paulson@15077
|
2413 |
apply (cut_tac [4] y = x in arctan_lbound)
|
paulson@15077
|
2414 |
apply (auto simp add: real_of_nat_Suc left_distrib mult_less_0_iff)
|
paulson@15077
|
2415 |
done
|
paulson@15077
|
2416 |
|
paulson@15077
|
2417 |
lemma tan_sec: "cos x \<noteq> 0 ==> 1 + tan(x) ^ 2 = inverse(cos x) ^ 2"
|
paulson@15077
|
2418 |
apply (rule power_inverse [THEN subst])
|
paulson@15077
|
2419 |
apply (rule_tac c1 = "(cos x)\<twosuperior>" in real_mult_right_cancel [THEN iffD1])
|
huffman@22960
|
2420 |
apply (auto dest: field_power_not_zero
|
huffman@20516
|
2421 |
simp add: power_mult_distrib left_distrib power_divide tan_def
|
huffman@30269
|
2422 |
mult_assoc power_inverse [symmetric])
|
paulson@15077
|
2423 |
done
|
paulson@15077
|
2424 |
|
huffman@23045
|
2425 |
lemma isCont_inverse_function2:
|
huffman@23045
|
2426 |
fixes f g :: "real \<Rightarrow> real" shows
|
huffman@23045
|
2427 |
"\<lbrakk>a < x; x < b;
|
huffman@23045
|
2428 |
\<forall>z. a \<le> z \<and> z \<le> b \<longrightarrow> g (f z) = z;
|
huffman@23045
|
2429 |
\<forall>z. a \<le> z \<and> z \<le> b \<longrightarrow> isCont f z\<rbrakk>
|
huffman@23045
|
2430 |
\<Longrightarrow> isCont g (f x)"
|
huffman@23045
|
2431 |
apply (rule isCont_inverse_function
|
huffman@23045
|
2432 |
[where f=f and d="min (x - a) (b - x)"])
|
huffman@23045
|
2433 |
apply (simp_all add: abs_le_iff)
|
huffman@23045
|
2434 |
done
|
huffman@23045
|
2435 |
|
huffman@23045
|
2436 |
lemma isCont_arcsin: "\<lbrakk>-1 < x; x < 1\<rbrakk> \<Longrightarrow> isCont arcsin x"
|
huffman@23045
|
2437 |
apply (subgoal_tac "isCont arcsin (sin (arcsin x))", simp)
|
huffman@23045
|
2438 |
apply (rule isCont_inverse_function2 [where f=sin])
|
huffman@23045
|
2439 |
apply (erule (1) arcsin_lt_bounded [THEN conjunct1])
|
huffman@23045
|
2440 |
apply (erule (1) arcsin_lt_bounded [THEN conjunct2])
|
huffman@23045
|
2441 |
apply (fast intro: arcsin_sin, simp)
|
huffman@23045
|
2442 |
done
|
huffman@23045
|
2443 |
|
huffman@23045
|
2444 |
lemma isCont_arccos: "\<lbrakk>-1 < x; x < 1\<rbrakk> \<Longrightarrow> isCont arccos x"
|
huffman@23045
|
2445 |
apply (subgoal_tac "isCont arccos (cos (arccos x))", simp)
|
huffman@23045
|
2446 |
apply (rule isCont_inverse_function2 [where f=cos])
|
huffman@23045
|
2447 |
apply (erule (1) arccos_lt_bounded [THEN conjunct1])
|
huffman@23045
|
2448 |
apply (erule (1) arccos_lt_bounded [THEN conjunct2])
|
huffman@23045
|
2449 |
apply (fast intro: arccos_cos, simp)
|
huffman@23045
|
2450 |
done
|
huffman@23045
|
2451 |
|
huffman@23045
|
2452 |
lemma isCont_arctan: "isCont arctan x"
|
huffman@23045
|
2453 |
apply (rule arctan_lbound [of x, THEN dense, THEN exE], clarify)
|
huffman@23045
|
2454 |
apply (rule arctan_ubound [of x, THEN dense, THEN exE], clarify)
|
huffman@23045
|
2455 |
apply (subgoal_tac "isCont arctan (tan (arctan x))", simp)
|
huffman@23045
|
2456 |
apply (erule (1) isCont_inverse_function2 [where f=tan])
|
huffman@23045
|
2457 |
apply (clarify, rule arctan_tan)
|
huffman@23045
|
2458 |
apply (erule (1) order_less_le_trans)
|
huffman@23045
|
2459 |
apply (erule (1) order_le_less_trans)
|
huffman@23045
|
2460 |
apply (clarify, rule isCont_tan)
|
huffman@23045
|
2461 |
apply (rule less_imp_neq [symmetric])
|
huffman@23045
|
2462 |
apply (rule cos_gt_zero_pi)
|
huffman@23045
|
2463 |
apply (erule (1) order_less_le_trans)
|
huffman@23045
|
2464 |
apply (erule (1) order_le_less_trans)
|
huffman@23045
|
2465 |
done
|
huffman@23045
|
2466 |
|
huffman@23045
|
2467 |
lemma DERIV_arcsin:
|
huffman@23045
|
2468 |
"\<lbrakk>-1 < x; x < 1\<rbrakk> \<Longrightarrow> DERIV arcsin x :> inverse (sqrt (1 - x\<twosuperior>))"
|
huffman@23045
|
2469 |
apply (rule DERIV_inverse_function [where f=sin and a="-1" and b="1"])
|
huffman@23045
|
2470 |
apply (rule lemma_DERIV_subst [OF DERIV_sin])
|
huffman@23045
|
2471 |
apply (simp add: cos_arcsin)
|
huffman@23045
|
2472 |
apply (subgoal_tac "\<bar>x\<bar>\<twosuperior> < 1\<twosuperior>", simp)
|
huffman@23045
|
2473 |
apply (rule power_strict_mono, simp, simp, simp)
|
huffman@23045
|
2474 |
apply assumption
|
huffman@23045
|
2475 |
apply assumption
|
huffman@23045
|
2476 |
apply simp
|
huffman@23045
|
2477 |
apply (erule (1) isCont_arcsin)
|
huffman@23045
|
2478 |
done
|
huffman@23045
|
2479 |
|
huffman@23045
|
2480 |
lemma DERIV_arccos:
|
huffman@23045
|
2481 |
"\<lbrakk>-1 < x; x < 1\<rbrakk> \<Longrightarrow> DERIV arccos x :> inverse (- sqrt (1 - x\<twosuperior>))"
|
huffman@23045
|
2482 |
apply (rule DERIV_inverse_function [where f=cos and a="-1" and b="1"])
|
huffman@23045
|
2483 |
apply (rule lemma_DERIV_subst [OF DERIV_cos])
|
huffman@23045
|
2484 |
apply (simp add: sin_arccos)
|
huffman@23045
|
2485 |
apply (subgoal_tac "\<bar>x\<bar>\<twosuperior> < 1\<twosuperior>", simp)
|
huffman@23045
|
2486 |
apply (rule power_strict_mono, simp, simp, simp)
|
huffman@23045
|
2487 |
apply assumption
|
huffman@23045
|
2488 |
apply assumption
|
huffman@23045
|
2489 |
apply simp
|
huffman@23045
|
2490 |
apply (erule (1) isCont_arccos)
|
huffman@23045
|
2491 |
done
|
huffman@23045
|
2492 |
|
huffman@23045
|
2493 |
lemma DERIV_arctan: "DERIV arctan x :> inverse (1 + x\<twosuperior>)"
|
huffman@23045
|
2494 |
apply (rule DERIV_inverse_function [where f=tan and a="x - 1" and b="x + 1"])
|
huffman@23045
|
2495 |
apply (rule lemma_DERIV_subst [OF DERIV_tan])
|
huffman@23045
|
2496 |
apply (rule cos_arctan_not_zero)
|
huffman@23045
|
2497 |
apply (simp add: power_inverse tan_sec [symmetric])
|
huffman@23045
|
2498 |
apply (subgoal_tac "0 < 1 + x\<twosuperior>", simp)
|
huffman@23045
|
2499 |
apply (simp add: add_pos_nonneg)
|
huffman@23045
|
2500 |
apply (simp, simp, simp, rule isCont_arctan)
|
huffman@23045
|
2501 |
done
|
huffman@23045
|
2502 |
|
hoelzl@31879
|
2503 |
declare
|
hoelzl@31879
|
2504 |
DERIV_arcsin[THEN DERIV_chain2, THEN DERIV_cong, DERIV_intros]
|
hoelzl@31879
|
2505 |
DERIV_arccos[THEN DERIV_chain2, THEN DERIV_cong, DERIV_intros]
|
hoelzl@31879
|
2506 |
DERIV_arctan[THEN DERIV_chain2, THEN DERIV_cong, DERIV_intros]
|
hoelzl@31879
|
2507 |
|
huffman@23043
|
2508 |
subsection {* More Theorems about Sin and Cos *}
|
huffman@23043
|
2509 |
|
huffman@23052
|
2510 |
lemma cos_45: "cos (pi / 4) = sqrt 2 / 2"
|
huffman@23052
|
2511 |
proof -
|
huffman@23052
|
2512 |
let ?c = "cos (pi / 4)" and ?s = "sin (pi / 4)"
|
huffman@23052
|
2513 |
have nonneg: "0 \<le> ?c"
|
huffman@23052
|
2514 |
by (rule cos_ge_zero, rule order_trans [where y=0], simp_all)
|
huffman@23052
|
2515 |
have "0 = cos (pi / 4 + pi / 4)"
|
huffman@23052
|
2516 |
by simp
|
huffman@23052
|
2517 |
also have "cos (pi / 4 + pi / 4) = ?c\<twosuperior> - ?s\<twosuperior>"
|
huffman@23052
|
2518 |
by (simp only: cos_add power2_eq_square)
|
huffman@23052
|
2519 |
also have "\<dots> = 2 * ?c\<twosuperior> - 1"
|
huffman@23052
|
2520 |
by (simp add: sin_squared_eq)
|
huffman@23052
|
2521 |
finally have "?c\<twosuperior> = (sqrt 2 / 2)\<twosuperior>"
|
huffman@23052
|
2522 |
by (simp add: power_divide)
|
huffman@23052
|
2523 |
thus ?thesis
|
huffman@23052
|
2524 |
using nonneg by (rule power2_eq_imp_eq) simp
|
huffman@23052
|
2525 |
qed
|
huffman@23052
|
2526 |
|
huffman@23052
|
2527 |
lemma cos_30: "cos (pi / 6) = sqrt 3 / 2"
|
huffman@23052
|
2528 |
proof -
|
huffman@23052
|
2529 |
let ?c = "cos (pi / 6)" and ?s = "sin (pi / 6)"
|
huffman@23052
|
2530 |
have pos_c: "0 < ?c"
|
huffman@23052
|
2531 |
by (rule cos_gt_zero, simp, simp)
|
huffman@23052
|
2532 |
have "0 = cos (pi / 6 + pi / 6 + pi / 6)"
|
huffman@23066
|
2533 |
by simp
|
huffman@23052
|
2534 |
also have "\<dots> = (?c * ?c - ?s * ?s) * ?c - (?s * ?c + ?c * ?s) * ?s"
|
huffman@23052
|
2535 |
by (simp only: cos_add sin_add)
|
huffman@23052
|
2536 |
also have "\<dots> = ?c * (?c\<twosuperior> - 3 * ?s\<twosuperior>)"
|
nipkow@29667
|
2537 |
by (simp add: algebra_simps power2_eq_square)
|
huffman@23052
|
2538 |
finally have "?c\<twosuperior> = (sqrt 3 / 2)\<twosuperior>"
|
huffman@23052
|
2539 |
using pos_c by (simp add: sin_squared_eq power_divide)
|
huffman@23052
|
2540 |
thus ?thesis
|
huffman@23052
|
2541 |
using pos_c [THEN order_less_imp_le]
|
huffman@23052
|
2542 |
by (rule power2_eq_imp_eq) simp
|
huffman@23052
|
2543 |
qed
|
huffman@23052
|
2544 |
|
huffman@23052
|
2545 |
lemma sin_45: "sin (pi / 4) = sqrt 2 / 2"
|
huffman@23052
|
2546 |
proof -
|
huffman@23052
|
2547 |
have "sin (pi / 4) = cos (pi / 2 - pi / 4)" by (rule sin_cos_eq)
|
huffman@23052
|
2548 |
also have "pi / 2 - pi / 4 = pi / 4" by simp
|
huffman@23052
|
2549 |
also have "cos (pi / 4) = sqrt 2 / 2" by (rule cos_45)
|
huffman@23052
|
2550 |
finally show ?thesis .
|
huffman@23052
|
2551 |
qed
|
huffman@23052
|
2552 |
|
huffman@23052
|
2553 |
lemma sin_60: "sin (pi / 3) = sqrt 3 / 2"
|
huffman@23052
|
2554 |
proof -
|
huffman@23052
|
2555 |
have "sin (pi / 3) = cos (pi / 2 - pi / 3)" by (rule sin_cos_eq)
|
huffman@23052
|
2556 |
also have "pi / 2 - pi / 3 = pi / 6" by simp
|
huffman@23052
|
2557 |
also have "cos (pi / 6) = sqrt 3 / 2" by (rule cos_30)
|
huffman@23052
|
2558 |
finally show ?thesis .
|
huffman@23052
|
2559 |
qed
|
huffman@23052
|
2560 |
|
huffman@23052
|
2561 |
lemma cos_60: "cos (pi / 3) = 1 / 2"
|
huffman@23052
|
2562 |
apply (rule power2_eq_imp_eq)
|
huffman@23052
|
2563 |
apply (simp add: cos_squared_eq sin_60 power_divide)
|
huffman@23052
|
2564 |
apply (rule cos_ge_zero, rule order_trans [where y=0], simp_all)
|
huffman@23052
|
2565 |
done
|
huffman@23052
|
2566 |
|
huffman@23052
|
2567 |
lemma sin_30: "sin (pi / 6) = 1 / 2"
|
huffman@23052
|
2568 |
proof -
|
huffman@23052
|
2569 |
have "sin (pi / 6) = cos (pi / 2 - pi / 6)" by (rule sin_cos_eq)
|
huffman@23066
|
2570 |
also have "pi / 2 - pi / 6 = pi / 3" by simp
|
huffman@23052
|
2571 |
also have "cos (pi / 3) = 1 / 2" by (rule cos_60)
|
huffman@23052
|
2572 |
finally show ?thesis .
|
huffman@23052
|
2573 |
qed
|
huffman@23052
|
2574 |
|
huffman@23052
|
2575 |
lemma tan_30: "tan (pi / 6) = 1 / sqrt 3"
|
huffman@23052
|
2576 |
unfolding tan_def by (simp add: sin_30 cos_30)
|
huffman@23052
|
2577 |
|
huffman@23052
|
2578 |
lemma tan_45: "tan (pi / 4) = 1"
|
huffman@23052
|
2579 |
unfolding tan_def by (simp add: sin_45 cos_45)
|
huffman@23052
|
2580 |
|
huffman@23052
|
2581 |
lemma tan_60: "tan (pi / 3) = sqrt 3"
|
huffman@23052
|
2582 |
unfolding tan_def by (simp add: sin_60 cos_60)
|
huffman@23052
|
2583 |
|
paulson@15085
|
2584 |
text{*NEEDED??*}
|
paulson@15229
|
2585 |
lemma [simp]:
|
paulson@15229
|
2586 |
"sin (x + 1 / 2 * real (Suc m) * pi) =
|
paulson@15229
|
2587 |
cos (x + 1 / 2 * real (m) * pi)"
|
paulson@15229
|
2588 |
by (simp only: cos_add sin_add real_of_nat_Suc left_distrib right_distrib, auto)
|
paulson@15077
|
2589 |
|
paulson@15085
|
2590 |
text{*NEEDED??*}
|
paulson@15229
|
2591 |
lemma [simp]:
|
paulson@15229
|
2592 |
"sin (x + real (Suc m) * pi / 2) =
|
paulson@15229
|
2593 |
cos (x + real (m) * pi / 2)"
|
paulson@15229
|
2594 |
by (simp only: cos_add sin_add real_of_nat_Suc add_divide_distrib left_distrib, auto)
|
paulson@15077
|
2595 |
|
paulson@15077
|
2596 |
lemma DERIV_sin_add [simp]: "DERIV (%x. sin (x + k)) xa :> cos (xa + k)"
|
paulson@15077
|
2597 |
apply (rule lemma_DERIV_subst)
|
paulson@15077
|
2598 |
apply (rule_tac f = sin and g = "%x. x + k" in DERIV_chain2)
|
paulson@15077
|
2599 |
apply (best intro!: DERIV_intros intro: DERIV_chain2)+
|
paulson@15077
|
2600 |
apply (simp (no_asm))
|
paulson@15077
|
2601 |
done
|
paulson@15077
|
2602 |
|
paulson@15383
|
2603 |
lemma sin_cos_npi [simp]: "sin (real (Suc (2 * n)) * pi / 2) = (-1) ^ n"
|
paulson@15383
|
2604 |
proof -
|
paulson@15383
|
2605 |
have "sin ((real n + 1/2) * pi) = cos (real n * pi)"
|
nipkow@29667
|
2606 |
by (auto simp add: algebra_simps sin_add)
|
paulson@15383
|
2607 |
thus ?thesis
|
paulson@15383
|
2608 |
by (simp add: real_of_nat_Suc left_distrib add_divide_distrib
|
paulson@15383
|
2609 |
mult_commute [of pi])
|
paulson@15383
|
2610 |
qed
|
paulson@15077
|
2611 |
|
paulson@15077
|
2612 |
lemma cos_2npi [simp]: "cos (2 * real (n::nat) * pi) = 1"
|
paulson@15077
|
2613 |
by (simp add: cos_double mult_assoc power_add [symmetric] numeral_2_eq_2)
|
paulson@15077
|
2614 |
|
paulson@15077
|
2615 |
lemma cos_3over2_pi [simp]: "cos (3 / 2 * pi) = 0"
|
huffman@23066
|
2616 |
apply (subgoal_tac "cos (pi + pi/2) = 0", simp)
|
huffman@23066
|
2617 |
apply (subst cos_add, simp)
|
paulson@15077
|
2618 |
done
|
paulson@15077
|
2619 |
|
paulson@15077
|
2620 |
lemma sin_2npi [simp]: "sin (2 * real (n::nat) * pi) = 0"
|
paulson@15077
|
2621 |
by (auto simp add: mult_assoc)
|
paulson@15077
|
2622 |
|
paulson@15077
|
2623 |
lemma sin_3over2_pi [simp]: "sin (3 / 2 * pi) = - 1"
|
huffman@23066
|
2624 |
apply (subgoal_tac "sin (pi + pi/2) = - 1", simp)
|
huffman@23066
|
2625 |
apply (subst sin_add, simp)
|
paulson@15077
|
2626 |
done
|
paulson@15077
|
2627 |
|
paulson@15077
|
2628 |
(*NEEDED??*)
|
paulson@15229
|
2629 |
lemma [simp]:
|
paulson@15229
|
2630 |
"cos(x + 1 / 2 * real(Suc m) * pi) = -sin (x + 1 / 2 * real m * pi)"
|
paulson@15077
|
2631 |
apply (simp only: cos_add sin_add real_of_nat_Suc right_distrib left_distrib minus_mult_right, auto)
|
paulson@15077
|
2632 |
done
|
paulson@15077
|
2633 |
|
paulson@15077
|
2634 |
(*NEEDED??*)
|
paulson@15077
|
2635 |
lemma [simp]: "cos (x + real(Suc m) * pi / 2) = -sin (x + real m * pi / 2)"
|
paulson@15229
|
2636 |
by (simp only: cos_add sin_add real_of_nat_Suc left_distrib add_divide_distrib, auto)
|
paulson@15077
|
2637 |
|
paulson@15077
|
2638 |
lemma cos_pi_eq_zero [simp]: "cos (pi * real (Suc (2 * m)) / 2) = 0"
|
paulson@15229
|
2639 |
by (simp only: cos_add sin_add real_of_nat_Suc left_distrib right_distrib add_divide_distrib, auto)
|
paulson@15077
|
2640 |
|
paulson@15077
|
2641 |
lemma DERIV_cos_add [simp]: "DERIV (%x. cos (x + k)) xa :> - sin (xa + k)"
|
paulson@15077
|
2642 |
apply (rule lemma_DERIV_subst)
|
paulson@15077
|
2643 |
apply (rule_tac f = cos and g = "%x. x + k" in DERIV_chain2)
|
paulson@15077
|
2644 |
apply (best intro!: DERIV_intros intro: DERIV_chain2)+
|
paulson@15077
|
2645 |
apply (simp (no_asm))
|
paulson@15077
|
2646 |
done
|
paulson@15077
|
2647 |
|
paulson@15081
|
2648 |
lemma sin_zero_abs_cos_one: "sin x = 0 ==> \<bar>cos x\<bar> = 1"
|
nipkow@15539
|
2649 |
by (auto simp add: sin_zero_iff even_mult_two_ex)
|
paulson@15077
|
2650 |
|
paulson@15077
|
2651 |
lemma cos_one_sin_zero: "cos x = 1 ==> sin x = 0"
|
paulson@15077
|
2652 |
by (cut_tac x = x in sin_cos_squared_add3, auto)
|
paulson@15077
|
2653 |
|
hoelzl@29740
|
2654 |
subsection {* Machins formula *}
|
hoelzl@29740
|
2655 |
|
hoelzl@29740
|
2656 |
lemma tan_total_pi4: assumes "\<bar>x\<bar> < 1"
|
hoelzl@29740
|
2657 |
shows "\<exists> z. - (pi / 4) < z \<and> z < pi / 4 \<and> tan z = x"
|
hoelzl@29740
|
2658 |
proof -
|
hoelzl@29740
|
2659 |
obtain z where "- (pi / 2) < z" and "z < pi / 2" and "tan z = x" using tan_total by blast
|
hoelzl@29740
|
2660 |
have "tan (pi / 4) = 1" and "tan (- (pi / 4)) = - 1" using tan_45 tan_minus by auto
|
hoelzl@29740
|
2661 |
have "z \<noteq> pi / 4"
|
hoelzl@29740
|
2662 |
proof (rule ccontr)
|
hoelzl@29740
|
2663 |
assume "\<not> (z \<noteq> pi / 4)" hence "z = pi / 4" by auto
|
hoelzl@29740
|
2664 |
have "tan z = 1" unfolding `z = pi / 4` `tan (pi / 4) = 1` ..
|
hoelzl@29740
|
2665 |
thus False unfolding `tan z = x` using `\<bar>x\<bar> < 1` by auto
|
hoelzl@29740
|
2666 |
qed
|
hoelzl@29740
|
2667 |
have "z \<noteq> - (pi / 4)"
|
hoelzl@29740
|
2668 |
proof (rule ccontr)
|
hoelzl@29740
|
2669 |
assume "\<not> (z \<noteq> - (pi / 4))" hence "z = - (pi / 4)" by auto
|
hoelzl@29740
|
2670 |
have "tan z = - 1" unfolding `z = - (pi / 4)` `tan (- (pi / 4)) = - 1` ..
|
hoelzl@29740
|
2671 |
thus False unfolding `tan z = x` using `\<bar>x\<bar> < 1` by auto
|
hoelzl@29740
|
2672 |
qed
|
hoelzl@29740
|
2673 |
|
hoelzl@29740
|
2674 |
have "z < pi / 4"
|
hoelzl@29740
|
2675 |
proof (rule ccontr)
|
hoelzl@29740
|
2676 |
assume "\<not> (z < pi / 4)" hence "pi / 4 < z" using `z \<noteq> pi / 4` by auto
|
hoelzl@29740
|
2677 |
have "- (pi / 2) < pi / 4" using m2pi_less_pi by auto
|
hoelzl@29740
|
2678 |
from tan_monotone[OF this `pi / 4 < z` `z < pi / 2`]
|
hoelzl@29740
|
2679 |
have "1 < x" unfolding `tan z = x` `tan (pi / 4) = 1` .
|
hoelzl@29740
|
2680 |
thus False using `\<bar>x\<bar> < 1` by auto
|
hoelzl@29740
|
2681 |
qed
|
hoelzl@29740
|
2682 |
moreover
|
hoelzl@29740
|
2683 |
have "-(pi / 4) < z"
|
hoelzl@29740
|
2684 |
proof (rule ccontr)
|
hoelzl@29740
|
2685 |
assume "\<not> (-(pi / 4) < z)" hence "z < - (pi / 4)" using `z \<noteq> - (pi / 4)` by auto
|
hoelzl@29740
|
2686 |
have "-(pi / 4) < pi / 2" using m2pi_less_pi by auto
|
hoelzl@29740
|
2687 |
from tan_monotone[OF `-(pi / 2) < z` `z < -(pi / 4)` this]
|
hoelzl@29740
|
2688 |
have "x < - 1" unfolding `tan z = x` `tan (-(pi / 4)) = - 1` .
|
hoelzl@29740
|
2689 |
thus False using `\<bar>x\<bar> < 1` by auto
|
hoelzl@29740
|
2690 |
qed
|
hoelzl@29740
|
2691 |
ultimately show ?thesis using `tan z = x` by auto
|
hoelzl@29740
|
2692 |
qed
|
hoelzl@29740
|
2693 |
|
hoelzl@29740
|
2694 |
lemma arctan_add: assumes "\<bar>x\<bar> \<le> 1" and "\<bar>y\<bar> < 1"
|
hoelzl@29740
|
2695 |
shows "arctan x + arctan y = arctan ((x + y) / (1 - x * y))"
|
hoelzl@29740
|
2696 |
proof -
|
hoelzl@29740
|
2697 |
obtain y' where "-(pi/4) < y'" and "y' < pi/4" and "tan y' = y" using tan_total_pi4[OF `\<bar>y\<bar> < 1`] by blast
|
hoelzl@29740
|
2698 |
|
hoelzl@29740
|
2699 |
have "pi / 4 < pi / 2" by auto
|
hoelzl@29740
|
2700 |
|
hoelzl@29740
|
2701 |
have "\<exists> x'. -(pi/4) \<le> x' \<and> x' \<le> pi/4 \<and> tan x' = x"
|
hoelzl@29740
|
2702 |
proof (cases "\<bar>x\<bar> < 1")
|
hoelzl@29740
|
2703 |
case True from tan_total_pi4[OF this] obtain x' where "-(pi/4) < x'" and "x' < pi/4" and "tan x' = x" by blast
|
hoelzl@29740
|
2704 |
hence "-(pi/4) \<le> x'" and "x' \<le> pi/4" and "tan x' = x" by auto
|
hoelzl@29740
|
2705 |
thus ?thesis by auto
|
hoelzl@29740
|
2706 |
next
|
hoelzl@29740
|
2707 |
case False
|
hoelzl@29740
|
2708 |
show ?thesis
|
hoelzl@29740
|
2709 |
proof (cases "x = 1")
|
hoelzl@29740
|
2710 |
case True hence "tan (pi/4) = x" using tan_45 by auto
|
hoelzl@29740
|
2711 |
moreover
|
hoelzl@29740
|
2712 |
have "- pi \<le> pi" unfolding minus_le_self_iff by auto
|
hoelzl@29740
|
2713 |
hence "-(pi/4) \<le> pi/4" and "pi/4 \<le> pi/4" by auto
|
hoelzl@29740
|
2714 |
ultimately show ?thesis by blast
|
hoelzl@29740
|
2715 |
next
|
hoelzl@29740
|
2716 |
case False hence "x = -1" using `\<not> \<bar>x\<bar> < 1` and `\<bar>x\<bar> \<le> 1` by auto
|
hoelzl@29740
|
2717 |
hence "tan (-(pi/4)) = x" using tan_45 tan_minus by auto
|
hoelzl@29740
|
2718 |
moreover
|
hoelzl@29740
|
2719 |
have "- pi \<le> pi" unfolding minus_le_self_iff by auto
|
hoelzl@29740
|
2720 |
hence "-(pi/4) \<le> pi/4" and "-(pi/4) \<le> -(pi/4)" by auto
|
hoelzl@29740
|
2721 |
ultimately show ?thesis by blast
|
hoelzl@29740
|
2722 |
qed
|
hoelzl@29740
|
2723 |
qed
|
hoelzl@29740
|
2724 |
then obtain x' where "-(pi/4) \<le> x'" and "x' \<le> pi/4" and "tan x' = x" by blast
|
hoelzl@29740
|
2725 |
hence "-(pi/2) < x'" and "x' < pi/2" using order_le_less_trans[OF `x' \<le> pi/4` `pi / 4 < pi / 2`] by auto
|
hoelzl@29740
|
2726 |
|
hoelzl@29740
|
2727 |
have "cos x' \<noteq> 0" using cos_gt_zero_pi[THEN less_imp_neq] and `-(pi/2) < x'` and `x' < pi/2` by auto
|
hoelzl@29740
|
2728 |
moreover have "cos y' \<noteq> 0" using cos_gt_zero_pi[THEN less_imp_neq] and `-(pi/4) < y'` and `y' < pi/4` by auto
|
hoelzl@29740
|
2729 |
ultimately have "cos x' * cos y' \<noteq> 0" by auto
|
hoelzl@29740
|
2730 |
|
hoelzl@29740
|
2731 |
have divide_nonzero_divide: "\<And> A B C :: real. C \<noteq> 0 \<Longrightarrow> (A / C) / (B / C) = A / B" by auto
|
hoelzl@29740
|
2732 |
have divide_mult_commute: "\<And> A B C D :: real. A * B / (C * D) = (A / C) * (B / D)" by auto
|
hoelzl@29740
|
2733 |
|
hoelzl@29740
|
2734 |
have "tan (x' + y') = sin (x' + y') / (cos x' * cos y' - sin x' * sin y')" unfolding tan_def cos_add ..
|
hoelzl@29740
|
2735 |
also have "\<dots> = (tan x' + tan y') / ((cos x' * cos y' - sin x' * sin y') / (cos x' * cos y'))" unfolding add_tan_eq[OF `cos x' \<noteq> 0` `cos y' \<noteq> 0`] divide_nonzero_divide[OF `cos x' * cos y' \<noteq> 0`] ..
|
hoelzl@29740
|
2736 |
also have "\<dots> = (tan x' + tan y') / (1 - tan x' * tan y')" unfolding tan_def diff_divide_distrib divide_self[OF `cos x' * cos y' \<noteq> 0`] unfolding divide_mult_commute ..
|
hoelzl@29740
|
2737 |
finally have tan_eq: "tan (x' + y') = (x + y) / (1 - x * y)" unfolding `tan y' = y` `tan x' = x` .
|
hoelzl@29740
|
2738 |
|
hoelzl@29740
|
2739 |
have "arctan (tan (x' + y')) = x' + y'" using `-(pi/4) < y'` `-(pi/4) \<le> x'` `y' < pi/4` and `x' \<le> pi/4` by (auto intro!: arctan_tan)
|
hoelzl@29740
|
2740 |
moreover have "arctan (tan (x')) = x'" using `-(pi/2) < x'` and `x' < pi/2` by (auto intro!: arctan_tan)
|
hoelzl@29740
|
2741 |
moreover have "arctan (tan (y')) = y'" using `-(pi/4) < y'` and `y' < pi/4` by (auto intro!: arctan_tan)
|
hoelzl@29740
|
2742 |
ultimately have "arctan x + arctan y = arctan (tan (x' + y'))" unfolding `tan y' = y` [symmetric] `tan x' = x`[symmetric] by auto
|
hoelzl@29740
|
2743 |
thus "arctan x + arctan y = arctan ((x + y) / (1 - x * y))" unfolding tan_eq .
|
hoelzl@29740
|
2744 |
qed
|
hoelzl@29740
|
2745 |
|
hoelzl@29740
|
2746 |
lemma arctan1_eq_pi4: "arctan 1 = pi / 4" unfolding tan_45[symmetric] by (rule arctan_tan, auto simp add: m2pi_less_pi)
|
hoelzl@29740
|
2747 |
|
hoelzl@29740
|
2748 |
theorem machin: "pi / 4 = 4 * arctan (1/5) - arctan (1 / 239)"
|
hoelzl@29740
|
2749 |
proof -
|
hoelzl@29740
|
2750 |
have "\<bar>1 / 5\<bar> < (1 :: real)" by auto
|
hoelzl@29740
|
2751 |
from arctan_add[OF less_imp_le[OF this] this]
|
hoelzl@29740
|
2752 |
have "2 * arctan (1 / 5) = arctan (5 / 12)" by auto
|
hoelzl@29740
|
2753 |
moreover
|
hoelzl@29740
|
2754 |
have "\<bar>5 / 12\<bar> < (1 :: real)" by auto
|
hoelzl@29740
|
2755 |
from arctan_add[OF less_imp_le[OF this] this]
|
hoelzl@29740
|
2756 |
have "2 * arctan (5 / 12) = arctan (120 / 119)" by auto
|
hoelzl@29740
|
2757 |
moreover
|
hoelzl@29740
|
2758 |
have "\<bar>1\<bar> \<le> (1::real)" and "\<bar>1 / 239\<bar> < (1::real)" by auto
|
hoelzl@29740
|
2759 |
from arctan_add[OF this]
|
hoelzl@29740
|
2760 |
have "arctan 1 + arctan (1 / 239) = arctan (120 / 119)" by auto
|
hoelzl@29740
|
2761 |
ultimately have "arctan 1 + arctan (1 / 239) = 4 * arctan (1 / 5)" by auto
|
hoelzl@29740
|
2762 |
thus ?thesis unfolding arctan1_eq_pi4 by algebra
|
hoelzl@29740
|
2763 |
qed
|
hoelzl@29740
|
2764 |
subsection {* Introducing the arcus tangens power series *}
|
hoelzl@29740
|
2765 |
|
hoelzl@29740
|
2766 |
lemma monoseq_arctan_series: fixes x :: real
|
hoelzl@29740
|
2767 |
assumes "\<bar>x\<bar> \<le> 1" shows "monoseq (\<lambda> n. 1 / real (n*2+1) * x^(n*2+1))" (is "monoseq ?a")
|
huffman@30019
|
2768 |
proof (cases "x = 0") case True thus ?thesis unfolding monoseq_def One_nat_def by auto
|
hoelzl@29740
|
2769 |
next
|
hoelzl@29740
|
2770 |
case False
|
hoelzl@29740
|
2771 |
have "norm x \<le> 1" and "x \<le> 1" and "-1 \<le> x" using assms by auto
|
hoelzl@29740
|
2772 |
show "monoseq ?a"
|
hoelzl@29740
|
2773 |
proof -
|
hoelzl@29740
|
2774 |
{ fix n fix x :: real assume "0 \<le> x" and "x \<le> 1"
|
hoelzl@29740
|
2775 |
have "1 / real (Suc (Suc n * 2)) * x ^ Suc (Suc n * 2) \<le> 1 / real (Suc (n * 2)) * x ^ Suc (n * 2)"
|
hoelzl@29740
|
2776 |
proof (rule mult_mono)
|
hoelzl@29740
|
2777 |
show "1 / real (Suc (Suc n * 2)) \<le> 1 / real (Suc (n * 2))" by (rule frac_le) simp_all
|
hoelzl@29740
|
2778 |
show "0 \<le> 1 / real (Suc (n * 2))" by auto
|
hoelzl@29740
|
2779 |
show "x ^ Suc (Suc n * 2) \<le> x ^ Suc (n * 2)" by (rule power_decreasing) (simp_all add: `0 \<le> x` `x \<le> 1`)
|
hoelzl@29740
|
2780 |
show "0 \<le> x ^ Suc (Suc n * 2)" by (rule zero_le_power) (simp add: `0 \<le> x`)
|
hoelzl@29740
|
2781 |
qed
|
hoelzl@29740
|
2782 |
} note mono = this
|
hoelzl@29740
|
2783 |
|
hoelzl@29740
|
2784 |
show ?thesis
|
hoelzl@29740
|
2785 |
proof (cases "0 \<le> x")
|
hoelzl@29740
|
2786 |
case True from mono[OF this `x \<le> 1`, THEN allI]
|
nipkow@31790
|
2787 |
show ?thesis unfolding Suc_eq_plus1[symmetric] by (rule mono_SucI2)
|
hoelzl@29740
|
2788 |
next
|
hoelzl@29740
|
2789 |
case False hence "0 \<le> -x" and "-x \<le> 1" using `-1 \<le> x` by auto
|
hoelzl@29740
|
2790 |
from mono[OF this]
|
hoelzl@29740
|
2791 |
have "\<And>n. 1 / real (Suc (Suc n * 2)) * x ^ Suc (Suc n * 2) \<ge> 1 / real (Suc (n * 2)) * x ^ Suc (n * 2)" using `0 \<le> -x` by auto
|
nipkow@31790
|
2792 |
thus ?thesis unfolding Suc_eq_plus1[symmetric] by (rule mono_SucI1[OF allI])
|
hoelzl@29740
|
2793 |
qed
|
hoelzl@29740
|
2794 |
qed
|
hoelzl@29740
|
2795 |
qed
|
hoelzl@29740
|
2796 |
|
hoelzl@29740
|
2797 |
lemma zeroseq_arctan_series: fixes x :: real
|
hoelzl@29740
|
2798 |
assumes "\<bar>x\<bar> \<le> 1" shows "(\<lambda> n. 1 / real (n*2+1) * x^(n*2+1)) ----> 0" (is "?a ----> 0")
|
huffman@30019
|
2799 |
proof (cases "x = 0") case True thus ?thesis unfolding One_nat_def by (auto simp add: LIMSEQ_const)
|
hoelzl@29740
|
2800 |
next
|
hoelzl@29740
|
2801 |
case False
|
hoelzl@29740
|
2802 |
have "norm x \<le> 1" and "x \<le> 1" and "-1 \<le> x" using assms by auto
|
hoelzl@29740
|
2803 |
show "?a ----> 0"
|
hoelzl@29740
|
2804 |
proof (cases "\<bar>x\<bar> < 1")
|
hoelzl@29740
|
2805 |
case True hence "norm x < 1" by auto
|
hoelzl@29740
|
2806 |
from LIMSEQ_mult[OF LIMSEQ_inverse_real_of_nat LIMSEQ_power_zero[OF `norm x < 1`, THEN LIMSEQ_Suc]]
|
huffman@30019
|
2807 |
have "(\<lambda>n. 1 / real (n + 1) * x ^ (n + 1)) ----> 0"
|
nipkow@31790
|
2808 |
unfolding inverse_eq_divide Suc_eq_plus1 by simp
|
huffman@30019
|
2809 |
then show ?thesis using pos2 by (rule LIMSEQ_linear)
|
hoelzl@29740
|
2810 |
next
|
hoelzl@29740
|
2811 |
case False hence "x = -1 \<or> x = 1" using `\<bar>x\<bar> \<le> 1` by auto
|
huffman@30019
|
2812 |
hence n_eq: "\<And> n. x ^ (n * 2 + 1) = x" unfolding One_nat_def by auto
|
hoelzl@29740
|
2813 |
from LIMSEQ_mult[OF LIMSEQ_inverse_real_of_nat[THEN LIMSEQ_linear, OF pos2, unfolded inverse_eq_divide] LIMSEQ_const[of x]]
|
nipkow@31790
|
2814 |
show ?thesis unfolding n_eq Suc_eq_plus1 by auto
|
hoelzl@29740
|
2815 |
qed
|
hoelzl@29740
|
2816 |
qed
|
hoelzl@29740
|
2817 |
|
hoelzl@29740
|
2818 |
lemma summable_arctan_series: fixes x :: real and n :: nat
|
hoelzl@29740
|
2819 |
assumes "\<bar>x\<bar> \<le> 1" shows "summable (\<lambda> k. (-1)^k * (1 / real (k*2+1) * x ^ (k*2+1)))" (is "summable (?c x)")
|
hoelzl@29740
|
2820 |
by (rule summable_Leibniz(1), rule zeroseq_arctan_series[OF assms], rule monoseq_arctan_series[OF assms])
|
hoelzl@29740
|
2821 |
|
hoelzl@29740
|
2822 |
lemma less_one_imp_sqr_less_one: fixes x :: real assumes "\<bar>x\<bar> < 1" shows "x^2 < 1"
|
hoelzl@29740
|
2823 |
proof -
|
hoelzl@29740
|
2824 |
from mult_mono1[OF less_imp_le[OF `\<bar>x\<bar> < 1`] abs_ge_zero[of x]]
|
hoelzl@29740
|
2825 |
have "\<bar> x^2 \<bar> < 1" using `\<bar> x \<bar> < 1` unfolding numeral_2_eq_2 power_Suc2 by auto
|
hoelzl@29740
|
2826 |
thus ?thesis using zero_le_power2 by auto
|
hoelzl@29740
|
2827 |
qed
|
hoelzl@29740
|
2828 |
|
hoelzl@29740
|
2829 |
lemma DERIV_arctan_series: assumes "\<bar> x \<bar> < 1"
|
hoelzl@29740
|
2830 |
shows "DERIV (\<lambda> x'. \<Sum> k. (-1)^k * (1 / real (k*2+1) * x' ^ (k*2+1))) x :> (\<Sum> k. (-1)^k * x^(k*2))" (is "DERIV ?arctan _ :> ?Int")
|
hoelzl@29740
|
2831 |
proof -
|
hoelzl@29740
|
2832 |
let "?f n" = "if even n then (-1)^(n div 2) * 1 / real (Suc n) else 0"
|
hoelzl@29740
|
2833 |
|
hoelzl@29740
|
2834 |
{ fix n :: nat assume "even n" hence "2 * (n div 2) = n" by presburger } note n_even=this
|
hoelzl@29740
|
2835 |
have if_eq: "\<And> n x'. ?f n * real (Suc n) * x'^n = (if even n then (-1)^(n div 2) * x'^(2 * (n div 2)) else 0)" using n_even by auto
|
hoelzl@29740
|
2836 |
|
hoelzl@29740
|
2837 |
{ fix x :: real assume "\<bar>x\<bar> < 1" hence "x^2 < 1" by (rule less_one_imp_sqr_less_one)
|
hoelzl@29740
|
2838 |
have "summable (\<lambda> n. -1 ^ n * (x^2) ^n)"
|
hoelzl@29740
|
2839 |
by (rule summable_Leibniz(1), auto intro!: LIMSEQ_realpow_zero monoseq_realpow `x^2 < 1` order_less_imp_le[OF `x^2 < 1`])
|
hoelzl@29740
|
2840 |
hence "summable (\<lambda> n. -1 ^ n * x^(2*n))" unfolding power_mult .
|
hoelzl@29740
|
2841 |
} note summable_Integral = this
|
hoelzl@29740
|
2842 |
|
hoelzl@29740
|
2843 |
{ fix f :: "nat \<Rightarrow> real"
|
hoelzl@29740
|
2844 |
have "\<And> x. f sums x = (\<lambda> n. if even n then f (n div 2) else 0) sums x"
|
hoelzl@29740
|
2845 |
proof
|
hoelzl@29740
|
2846 |
fix x :: real assume "f sums x"
|
hoelzl@29740
|
2847 |
from sums_if[OF sums_zero this]
|
hoelzl@29740
|
2848 |
show "(\<lambda> n. if even n then f (n div 2) else 0) sums x" by auto
|
hoelzl@29740
|
2849 |
next
|
hoelzl@29740
|
2850 |
fix x :: real assume "(\<lambda> n. if even n then f (n div 2) else 0) sums x"
|
hoelzl@29740
|
2851 |
from LIMSEQ_linear[OF this[unfolded sums_def] pos2, unfolded sum_split_even_odd[unfolded mult_commute]]
|
hoelzl@29740
|
2852 |
show "f sums x" unfolding sums_def by auto
|
hoelzl@29740
|
2853 |
qed
|
hoelzl@29740
|
2854 |
hence "op sums f = op sums (\<lambda> n. if even n then f (n div 2) else 0)" ..
|
hoelzl@29740
|
2855 |
} note sums_even = this
|
hoelzl@29740
|
2856 |
|
hoelzl@29740
|
2857 |
have Int_eq: "(\<Sum> n. ?f n * real (Suc n) * x^n) = ?Int" unfolding if_eq mult_commute[of _ 2] suminf_def sums_even[of "\<lambda> n. -1 ^ n * x ^ (2 * n)", symmetric]
|
hoelzl@29740
|
2858 |
by auto
|
hoelzl@29740
|
2859 |
|
hoelzl@29740
|
2860 |
{ fix x :: real
|
hoelzl@29740
|
2861 |
have if_eq': "\<And> n. (if even n then -1 ^ (n div 2) * 1 / real (Suc n) else 0) * x ^ Suc n =
|
hoelzl@29740
|
2862 |
(if even n then -1 ^ (n div 2) * (1 / real (Suc (2 * (n div 2))) * x ^ Suc (2 * (n div 2))) else 0)"
|
hoelzl@29740
|
2863 |
using n_even by auto
|
hoelzl@29740
|
2864 |
have idx_eq: "\<And> n. n * 2 + 1 = Suc (2 * n)" by auto
|
hoelzl@29740
|
2865 |
have "(\<Sum> n. ?f n * x^(Suc n)) = ?arctan x" unfolding if_eq' idx_eq suminf_def sums_even[of "\<lambda> n. -1 ^ n * (1 / real (Suc (2 * n)) * x ^ Suc (2 * n))", symmetric]
|
hoelzl@29740
|
2866 |
by auto
|
hoelzl@29740
|
2867 |
} note arctan_eq = this
|
hoelzl@29740
|
2868 |
|
hoelzl@29740
|
2869 |
have "DERIV (\<lambda> x. \<Sum> n. ?f n * x^(Suc n)) x :> (\<Sum> n. ?f n * real (Suc n) * x^n)"
|
hoelzl@29740
|
2870 |
proof (rule DERIV_power_series')
|
hoelzl@29740
|
2871 |
show "x \<in> {- 1 <..< 1}" using `\<bar> x \<bar> < 1` by auto
|
hoelzl@29740
|
2872 |
{ fix x' :: real assume x'_bounds: "x' \<in> {- 1 <..< 1}"
|
hoelzl@29740
|
2873 |
hence "\<bar>x'\<bar> < 1" by auto
|
hoelzl@29740
|
2874 |
|
hoelzl@29740
|
2875 |
let ?S = "\<Sum> n. (-1)^n * x'^(2 * n)"
|
hoelzl@29740
|
2876 |
show "summable (\<lambda> n. ?f n * real (Suc n) * x'^n)" unfolding if_eq
|
hoelzl@29740
|
2877 |
by (rule sums_summable[where l="0 + ?S"], rule sums_if, rule sums_zero, rule summable_sums, rule summable_Integral[OF `\<bar>x'\<bar> < 1`])
|
hoelzl@29740
|
2878 |
}
|
hoelzl@29740
|
2879 |
qed auto
|
hoelzl@29740
|
2880 |
thus ?thesis unfolding Int_eq arctan_eq .
|
hoelzl@29740
|
2881 |
qed
|
hoelzl@29740
|
2882 |
|
hoelzl@29740
|
2883 |
lemma arctan_series: assumes "\<bar> x \<bar> \<le> 1"
|
hoelzl@29740
|
2884 |
shows "arctan x = (\<Sum> k. (-1)^k * (1 / real (k*2+1) * x ^ (k*2+1)))" (is "_ = suminf (\<lambda> n. ?c x n)")
|
hoelzl@29740
|
2885 |
proof -
|
hoelzl@29740
|
2886 |
let "?c' x n" = "(-1)^n * x^(n*2)"
|
hoelzl@29740
|
2887 |
|
hoelzl@29740
|
2888 |
{ fix r x :: real assume "0 < r" and "r < 1" and "\<bar> x \<bar> < r"
|
hoelzl@29740
|
2889 |
have "\<bar>x\<bar> < 1" using `r < 1` and `\<bar>x\<bar> < r` by auto
|
hoelzl@29740
|
2890 |
from DERIV_arctan_series[OF this]
|
hoelzl@29740
|
2891 |
have "DERIV (\<lambda> x. suminf (?c x)) x :> (suminf (?c' x))" .
|
hoelzl@29740
|
2892 |
} note DERIV_arctan_suminf = this
|
hoelzl@29740
|
2893 |
|
hoelzl@29740
|
2894 |
{ fix x :: real assume "\<bar>x\<bar> \<le> 1" note summable_Leibniz[OF zeroseq_arctan_series[OF this] monoseq_arctan_series[OF this]] }
|
hoelzl@29740
|
2895 |
note arctan_series_borders = this
|
hoelzl@29740
|
2896 |
|
hoelzl@29740
|
2897 |
{ fix x :: real assume "\<bar>x\<bar> < 1" have "arctan x = (\<Sum> k. ?c x k)"
|
hoelzl@29740
|
2898 |
proof -
|
hoelzl@29740
|
2899 |
obtain r where "\<bar>x\<bar> < r" and "r < 1" using dense[OF `\<bar>x\<bar> < 1`] by blast
|
hoelzl@29740
|
2900 |
hence "0 < r" and "-r < x" and "x < r" by auto
|
hoelzl@29740
|
2901 |
|
hoelzl@29740
|
2902 |
have suminf_eq_arctan_bounded: "\<And> x a b. \<lbrakk> -r < a ; b < r ; a < b ; a \<le> x ; x \<le> b \<rbrakk> \<Longrightarrow> suminf (?c x) - arctan x = suminf (?c a) - arctan a"
|
hoelzl@29740
|
2903 |
proof -
|
hoelzl@29740
|
2904 |
fix x a b assume "-r < a" and "b < r" and "a < b" and "a \<le> x" and "x \<le> b"
|
hoelzl@29740
|
2905 |
hence "\<bar>x\<bar> < r" by auto
|
hoelzl@29740
|
2906 |
show "suminf (?c x) - arctan x = suminf (?c a) - arctan a"
|
hoelzl@29740
|
2907 |
proof (rule DERIV_isconst2[of "a" "b"])
|
hoelzl@29740
|
2908 |
show "a < b" and "a \<le> x" and "x \<le> b" using `a < b` `a \<le> x` `x \<le> b` by auto
|
hoelzl@29740
|
2909 |
have "\<forall> x. -r < x \<and> x < r \<longrightarrow> DERIV (\<lambda> x. suminf (?c x) - arctan x) x :> 0"
|
hoelzl@29740
|
2910 |
proof (rule allI, rule impI)
|
hoelzl@29740
|
2911 |
fix x assume "-r < x \<and> x < r" hence "\<bar>x\<bar> < r" by auto
|
hoelzl@29740
|
2912 |
hence "\<bar>x\<bar> < 1" using `r < 1` by auto
|
hoelzl@29740
|
2913 |
have "\<bar> - (x^2) \<bar> < 1" using less_one_imp_sqr_less_one[OF `\<bar>x\<bar> < 1`] by auto
|
hoelzl@29740
|
2914 |
hence "(\<lambda> n. (- (x^2)) ^ n) sums (1 / (1 - (- (x^2))))" unfolding real_norm_def[symmetric] by (rule geometric_sums)
|
hoelzl@29740
|
2915 |
hence "(?c' x) sums (1 / (1 - (- (x^2))))" unfolding power_mult_distrib[symmetric] power_mult nat_mult_commute[of _ 2] by auto
|
hoelzl@29740
|
2916 |
hence suminf_c'_eq_geom: "inverse (1 + x^2) = suminf (?c' x)" using sums_unique unfolding inverse_eq_divide by auto
|
hoelzl@29740
|
2917 |
have "DERIV (\<lambda> x. suminf (?c x)) x :> (inverse (1 + x^2))" unfolding suminf_c'_eq_geom
|
hoelzl@29740
|
2918 |
by (rule DERIV_arctan_suminf[OF `0 < r` `r < 1` `\<bar>x\<bar> < r`])
|
hoelzl@29740
|
2919 |
from DERIV_add_minus[OF this DERIV_arctan]
|
hoelzl@29740
|
2920 |
show "DERIV (\<lambda> x. suminf (?c x) - arctan x) x :> 0" unfolding diff_minus by auto
|
hoelzl@29740
|
2921 |
qed
|
hoelzl@29740
|
2922 |
hence DERIV_in_rball: "\<forall> y. a \<le> y \<and> y \<le> b \<longrightarrow> DERIV (\<lambda> x. suminf (?c x) - arctan x) y :> 0" using `-r < a` `b < r` by auto
|
hoelzl@29740
|
2923 |
thus "\<forall> y. a < y \<and> y < b \<longrightarrow> DERIV (\<lambda> x. suminf (?c x) - arctan x) y :> 0" using `\<bar>x\<bar> < r` by auto
|
hoelzl@29740
|
2924 |
show "\<forall> y. a \<le> y \<and> y \<le> b \<longrightarrow> isCont (\<lambda> x. suminf (?c x) - arctan x) y" using DERIV_in_rball DERIV_isCont by auto
|
hoelzl@29740
|
2925 |
qed
|
hoelzl@29740
|
2926 |
qed
|
hoelzl@29740
|
2927 |
|
hoelzl@29740
|
2928 |
have suminf_arctan_zero: "suminf (?c 0) - arctan 0 = 0"
|
nipkow@31790
|
2929 |
unfolding Suc_eq_plus1[symmetric] power_Suc2 mult_zero_right arctan_zero_zero suminf_zero by auto
|
hoelzl@29740
|
2930 |
|
hoelzl@29740
|
2931 |
have "suminf (?c x) - arctan x = 0"
|
hoelzl@29740
|
2932 |
proof (cases "x = 0")
|
hoelzl@29740
|
2933 |
case True thus ?thesis using suminf_arctan_zero by auto
|
hoelzl@29740
|
2934 |
next
|
hoelzl@29740
|
2935 |
case False hence "0 < \<bar>x\<bar>" and "- \<bar>x\<bar> < \<bar>x\<bar>" by auto
|
hoelzl@29740
|
2936 |
have "suminf (?c (-\<bar>x\<bar>)) - arctan (-\<bar>x\<bar>) = suminf (?c 0) - arctan 0"
|
hoelzl@29740
|
2937 |
by (rule suminf_eq_arctan_bounded[where x="0" and a="-\<bar>x\<bar>" and b="\<bar>x\<bar>", symmetric], auto simp add: `\<bar>x\<bar> < r` `-\<bar>x\<bar> < \<bar>x\<bar>`)
|
hoelzl@29740
|
2938 |
moreover
|
hoelzl@29740
|
2939 |
have "suminf (?c x) - arctan x = suminf (?c (-\<bar>x\<bar>)) - arctan (-\<bar>x\<bar>)"
|
hoelzl@29740
|
2940 |
by (rule suminf_eq_arctan_bounded[where x="x" and a="-\<bar>x\<bar>" and b="\<bar>x\<bar>"], auto simp add: `\<bar>x\<bar> < r` `-\<bar>x\<bar> < \<bar>x\<bar>`)
|
hoelzl@29740
|
2941 |
ultimately
|
hoelzl@29740
|
2942 |
show ?thesis using suminf_arctan_zero by auto
|
hoelzl@29740
|
2943 |
qed
|
hoelzl@29740
|
2944 |
thus ?thesis by auto
|
hoelzl@29740
|
2945 |
qed } note when_less_one = this
|
hoelzl@29740
|
2946 |
|
hoelzl@29740
|
2947 |
show "arctan x = suminf (\<lambda> n. ?c x n)"
|
hoelzl@29740
|
2948 |
proof (cases "\<bar>x\<bar> < 1")
|
hoelzl@29740
|
2949 |
case True thus ?thesis by (rule when_less_one)
|
hoelzl@29740
|
2950 |
next case False hence "\<bar>x\<bar> = 1" using `\<bar>x\<bar> \<le> 1` by auto
|
hoelzl@29740
|
2951 |
let "?a x n" = "\<bar>1 / real (n*2+1) * x^(n*2+1)\<bar>"
|
hoelzl@29740
|
2952 |
let "?diff x n" = "\<bar> arctan x - (\<Sum> i = 0..<n. ?c x i)\<bar>"
|
hoelzl@29740
|
2953 |
{ fix n :: nat
|
hoelzl@29740
|
2954 |
have "0 < (1 :: real)" by auto
|
hoelzl@29740
|
2955 |
moreover
|
hoelzl@29740
|
2956 |
{ fix x :: real assume "0 < x" and "x < 1" hence "\<bar>x\<bar> \<le> 1" and "\<bar>x\<bar> < 1" by auto
|
hoelzl@29740
|
2957 |
from `0 < x` have "0 < 1 / real (0 * 2 + (1::nat)) * x ^ (0 * 2 + 1)" by auto
|
hoelzl@29740
|
2958 |
note bounds = mp[OF arctan_series_borders(2)[OF `\<bar>x\<bar> \<le> 1`] this, unfolded when_less_one[OF `\<bar>x\<bar> < 1`, symmetric], THEN spec]
|
hoelzl@29740
|
2959 |
have "0 < 1 / real (n*2+1) * x^(n*2+1)" by (rule mult_pos_pos, auto simp only: zero_less_power[OF `0 < x`], auto)
|
hoelzl@29740
|
2960 |
hence a_pos: "?a x n = 1 / real (n*2+1) * x^(n*2+1)" by (rule abs_of_pos)
|
hoelzl@29740
|
2961 |
have "?diff x n \<le> ?a x n"
|
hoelzl@29740
|
2962 |
proof (cases "even n")
|
hoelzl@29740
|
2963 |
case True hence sgn_pos: "(-1)^n = (1::real)" by auto
|
hoelzl@29740
|
2964 |
from `even n` obtain m where "2 * m = n" unfolding even_mult_two_ex by auto
|
hoelzl@29740
|
2965 |
from bounds[of m, unfolded this atLeastAtMost_iff]
|
hoelzl@29740
|
2966 |
have "\<bar>arctan x - (\<Sum>i = 0..<n. (?c x i))\<bar> \<le> (\<Sum>i = 0..<n + 1. (?c x i)) - (\<Sum>i = 0..<n. (?c x i))" by auto
|
huffman@30019
|
2967 |
also have "\<dots> = ?c x n" unfolding One_nat_def by auto
|
hoelzl@29740
|
2968 |
also have "\<dots> = ?a x n" unfolding sgn_pos a_pos by auto
|
hoelzl@29740
|
2969 |
finally show ?thesis .
|
hoelzl@29740
|
2970 |
next
|
hoelzl@29740
|
2971 |
case False hence sgn_neg: "(-1)^n = (-1::real)" by auto
|
hoelzl@29740
|
2972 |
from `odd n` obtain m where m_def: "2 * m + 1 = n" unfolding odd_Suc_mult_two_ex by auto
|
hoelzl@29740
|
2973 |
hence m_plus: "2 * (m + 1) = n + 1" by auto
|
hoelzl@29740
|
2974 |
from bounds[of "m + 1", unfolded this atLeastAtMost_iff, THEN conjunct1] bounds[of m, unfolded m_def atLeastAtMost_iff, THEN conjunct2]
|
hoelzl@29740
|
2975 |
have "\<bar>arctan x - (\<Sum>i = 0..<n. (?c x i))\<bar> \<le> (\<Sum>i = 0..<n. (?c x i)) - (\<Sum>i = 0..<n+1. (?c x i))" by auto
|
huffman@30019
|
2976 |
also have "\<dots> = - ?c x n" unfolding One_nat_def by auto
|
hoelzl@29740
|
2977 |
also have "\<dots> = ?a x n" unfolding sgn_neg a_pos by auto
|
hoelzl@29740
|
2978 |
finally show ?thesis .
|
hoelzl@29740
|
2979 |
qed
|
hoelzl@29740
|
2980 |
hence "0 \<le> ?a x n - ?diff x n" by auto
|
hoelzl@29740
|
2981 |
}
|
hoelzl@29740
|
2982 |
hence "\<forall> x \<in> { 0 <..< 1 }. 0 \<le> ?a x n - ?diff x n" by auto
|
hoelzl@29740
|
2983 |
moreover have "\<And>x. isCont (\<lambda> x. ?a x n - ?diff x n) x"
|
hoelzl@29740
|
2984 |
unfolding real_diff_def divide_inverse
|
hoelzl@29740
|
2985 |
by (auto intro!: isCont_add isCont_rabs isCont_ident isCont_minus isCont_arctan isCont_inverse isCont_mult isCont_power isCont_const isCont_setsum)
|
hoelzl@29740
|
2986 |
ultimately have "0 \<le> ?a 1 n - ?diff 1 n" by (rule LIM_less_bound)
|
hoelzl@29740
|
2987 |
hence "?diff 1 n \<le> ?a 1 n" by auto
|
hoelzl@29740
|
2988 |
}
|
huffman@30019
|
2989 |
have "?a 1 ----> 0"
|
huffman@30019
|
2990 |
unfolding LIMSEQ_rabs_zero power_one divide_inverse One_nat_def
|
huffman@30019
|
2991 |
by (auto intro!: LIMSEQ_mult LIMSEQ_linear LIMSEQ_inverse_real_of_nat)
|
hoelzl@29740
|
2992 |
have "?diff 1 ----> 0"
|
hoelzl@29740
|
2993 |
proof (rule LIMSEQ_I)
|
hoelzl@29740
|
2994 |
fix r :: real assume "0 < r"
|
hoelzl@29740
|
2995 |
obtain N :: nat where N_I: "\<And> n. N \<le> n \<Longrightarrow> ?a 1 n < r" using LIMSEQ_D[OF `?a 1 ----> 0` `0 < r`] by auto
|
hoelzl@29740
|
2996 |
{ fix n assume "N \<le> n" from `?diff 1 n \<le> ?a 1 n` N_I[OF this]
|
hoelzl@29740
|
2997 |
have "norm (?diff 1 n - 0) < r" by auto }
|
hoelzl@29740
|
2998 |
thus "\<exists> N. \<forall> n \<ge> N. norm (?diff 1 n - 0) < r" by blast
|
hoelzl@29740
|
2999 |
qed
|
hoelzl@29740
|
3000 |
from this[unfolded LIMSEQ_rabs_zero real_diff_def add_commute[of "arctan 1"], THEN LIMSEQ_add_const, of "- arctan 1", THEN LIMSEQ_minus]
|
hoelzl@29740
|
3001 |
have "(?c 1) sums (arctan 1)" unfolding sums_def by auto
|
hoelzl@29740
|
3002 |
hence "arctan 1 = (\<Sum> i. ?c 1 i)" by (rule sums_unique)
|
hoelzl@29740
|
3003 |
|
hoelzl@29740
|
3004 |
show ?thesis
|
hoelzl@29740
|
3005 |
proof (cases "x = 1", simp add: `arctan 1 = (\<Sum> i. ?c 1 i)`)
|
hoelzl@29740
|
3006 |
assume "x \<noteq> 1" hence "x = -1" using `\<bar>x\<bar> = 1` by auto
|
hoelzl@29740
|
3007 |
|
hoelzl@29740
|
3008 |
have "- (pi / 2) < 0" using pi_gt_zero by auto
|
hoelzl@29740
|
3009 |
have "- (2 * pi) < 0" using pi_gt_zero by auto
|
hoelzl@29740
|
3010 |
|
huffman@30019
|
3011 |
have c_minus_minus: "\<And> i. ?c (- 1) i = - ?c 1 i" unfolding One_nat_def by auto
|
hoelzl@29740
|
3012 |
|
hoelzl@29740
|
3013 |
have "arctan (- 1) = arctan (tan (-(pi / 4)))" unfolding tan_45 tan_minus ..
|
hoelzl@29740
|
3014 |
also have "\<dots> = - (pi / 4)" by (rule arctan_tan, auto simp add: order_less_trans[OF `- (pi / 2) < 0` pi_gt_zero])
|
hoelzl@29740
|
3015 |
also have "\<dots> = - (arctan (tan (pi / 4)))" unfolding neg_equal_iff_equal by (rule arctan_tan[symmetric], auto simp add: order_less_trans[OF `- (2 * pi) < 0` pi_gt_zero])
|
hoelzl@29740
|
3016 |
also have "\<dots> = - (arctan 1)" unfolding tan_45 ..
|
hoelzl@29740
|
3017 |
also have "\<dots> = - (\<Sum> i. ?c 1 i)" using `arctan 1 = (\<Sum> i. ?c 1 i)` by auto
|
hoelzl@29740
|
3018 |
also have "\<dots> = (\<Sum> i. ?c (- 1) i)" using suminf_minus[OF sums_summable[OF `(?c 1) sums (arctan 1)`]] unfolding c_minus_minus by auto
|
hoelzl@29740
|
3019 |
finally show ?thesis using `x = -1` by auto
|
hoelzl@29740
|
3020 |
qed
|
hoelzl@29740
|
3021 |
qed
|
hoelzl@29740
|
3022 |
qed
|
hoelzl@29740
|
3023 |
|
hoelzl@29740
|
3024 |
lemma arctan_half: fixes x :: real
|
hoelzl@29740
|
3025 |
shows "arctan x = 2 * arctan (x / (1 + sqrt(1 + x^2)))"
|
hoelzl@29740
|
3026 |
proof -
|
hoelzl@29740
|
3027 |
obtain y where low: "- (pi / 2) < y" and high: "y < pi / 2" and y_eq: "tan y = x" using tan_total by blast
|
hoelzl@29740
|
3028 |
hence low2: "- (pi / 2) < y / 2" and high2: "y / 2 < pi / 2" by auto
|
hoelzl@29740
|
3029 |
|
hoelzl@29740
|
3030 |
have divide_nonzero_divide: "\<And> A B C :: real. C \<noteq> 0 \<Longrightarrow> A / B = (A / C) / (B / C)" by auto
|
hoelzl@29740
|
3031 |
|
hoelzl@29740
|
3032 |
have "0 < cos y" using cos_gt_zero_pi[OF low high] .
|
hoelzl@29740
|
3033 |
hence "cos y \<noteq> 0" and cos_sqrt: "sqrt ((cos y) ^ 2) = cos y" by auto
|
hoelzl@29740
|
3034 |
|
hoelzl@29740
|
3035 |
have "1 + (tan y)^2 = 1 + sin y^2 / cos y^2" unfolding tan_def power_divide ..
|
hoelzl@29740
|
3036 |
also have "\<dots> = cos y^2 / cos y^2 + sin y^2 / cos y^2" using `cos y \<noteq> 0` by auto
|
hoelzl@29740
|
3037 |
also have "\<dots> = 1 / cos y^2" unfolding add_divide_distrib[symmetric] sin_cos_squared_add2 ..
|
hoelzl@29740
|
3038 |
finally have "1 + (tan y)^2 = 1 / cos y^2" .
|
hoelzl@29740
|
3039 |
|
hoelzl@29740
|
3040 |
have "sin y / (cos y + 1) = tan y / ((cos y + 1) / cos y)" unfolding tan_def divide_nonzero_divide[OF `cos y \<noteq> 0`, symmetric] ..
|
hoelzl@29740
|
3041 |
also have "\<dots> = tan y / (1 + 1 / cos y)" using `cos y \<noteq> 0` unfolding add_divide_distrib by auto
|
hoelzl@29740
|
3042 |
also have "\<dots> = tan y / (1 + 1 / sqrt(cos y^2))" unfolding cos_sqrt ..
|
hoelzl@29740
|
3043 |
also have "\<dots> = tan y / (1 + sqrt(1 / cos y^2))" unfolding real_sqrt_divide by auto
|
hoelzl@29740
|
3044 |
finally have eq: "sin y / (cos y + 1) = tan y / (1 + sqrt(1 + (tan y)^2))" unfolding `1 + (tan y)^2 = 1 / cos y^2` .
|
hoelzl@29740
|
3045 |
|
hoelzl@29740
|
3046 |
have "arctan x = y" using arctan_tan low high y_eq by auto
|
hoelzl@29740
|
3047 |
also have "\<dots> = 2 * (arctan (tan (y/2)))" using arctan_tan[OF low2 high2] by auto
|
hoelzl@29740
|
3048 |
also have "\<dots> = 2 * (arctan (sin y / (cos y + 1)))" unfolding tan_half[OF low2 high2] by auto
|
hoelzl@29740
|
3049 |
finally show ?thesis unfolding eq `tan y = x` .
|
hoelzl@29740
|
3050 |
qed
|
hoelzl@29740
|
3051 |
|
hoelzl@29740
|
3052 |
lemma arctan_monotone: assumes "x < y"
|
hoelzl@29740
|
3053 |
shows "arctan x < arctan y"
|
hoelzl@29740
|
3054 |
proof -
|
hoelzl@29740
|
3055 |
obtain z where "-(pi / 2) < z" and "z < pi / 2" and "tan z = x" using tan_total by blast
|
hoelzl@29740
|
3056 |
obtain w where "-(pi / 2) < w" and "w < pi / 2" and "tan w = y" using tan_total by blast
|
hoelzl@29740
|
3057 |
have "z < w" unfolding tan_monotone'[OF `-(pi / 2) < z` `z < pi / 2` `-(pi / 2) < w` `w < pi / 2`] `tan z = x` `tan w = y` using `x < y` .
|
hoelzl@29740
|
3058 |
thus ?thesis
|
hoelzl@29740
|
3059 |
unfolding `tan z = x`[symmetric] arctan_tan[OF `-(pi / 2) < z` `z < pi / 2`]
|
hoelzl@29740
|
3060 |
unfolding `tan w = y`[symmetric] arctan_tan[OF `-(pi / 2) < w` `w < pi / 2`] .
|
hoelzl@29740
|
3061 |
qed
|
hoelzl@29740
|
3062 |
|
hoelzl@29740
|
3063 |
lemma arctan_monotone': assumes "x \<le> y" shows "arctan x \<le> arctan y"
|
hoelzl@29740
|
3064 |
proof (cases "x = y")
|
hoelzl@29740
|
3065 |
case False hence "x < y" using `x \<le> y` by auto from arctan_monotone[OF this] show ?thesis by auto
|
hoelzl@29740
|
3066 |
qed auto
|
hoelzl@29740
|
3067 |
|
hoelzl@29740
|
3068 |
lemma arctan_minus: "arctan (- x) = - arctan x"
|
hoelzl@29740
|
3069 |
proof -
|
hoelzl@29740
|
3070 |
obtain y where "- (pi / 2) < y" and "y < pi / 2" and "tan y = x" using tan_total by blast
|
hoelzl@29740
|
3071 |
thus ?thesis unfolding `tan y = x`[symmetric] tan_minus[symmetric] using arctan_tan[of y] arctan_tan[of "-y"] by auto
|
hoelzl@29740
|
3072 |
qed
|
hoelzl@29740
|
3073 |
|
hoelzl@29740
|
3074 |
lemma arctan_inverse: assumes "x \<noteq> 0" shows "arctan (1 / x) = sgn x * pi / 2 - arctan x"
|
hoelzl@29740
|
3075 |
proof -
|
hoelzl@29740
|
3076 |
obtain y where "- (pi / 2) < y" and "y < pi / 2" and "tan y = x" using tan_total by blast
|
hoelzl@29740
|
3077 |
hence "y = arctan x" unfolding `tan y = x`[symmetric] using arctan_tan by auto
|
hoelzl@29740
|
3078 |
|
hoelzl@29740
|
3079 |
{ fix y x :: real assume "0 < y" and "y < pi /2" and "y = arctan x" and "tan y = x" hence "- (pi / 2) < y" by auto
|
hoelzl@29740
|
3080 |
have "tan y > 0" using tan_monotone'[OF _ _ `- (pi / 2) < y` `y < pi / 2`, of 0] tan_zero `0 < y` by auto
|
hoelzl@29740
|
3081 |
hence "x > 0" using `tan y = x` by auto
|
hoelzl@29740
|
3082 |
|
hoelzl@29740
|
3083 |
have "- (pi / 2) < pi / 2 - y" using `y > 0` `y < pi / 2` by auto
|
hoelzl@29740
|
3084 |
moreover have "pi / 2 - y < pi / 2" using `y > 0` `y < pi / 2` by auto
|
hoelzl@29740
|
3085 |
ultimately have "arctan (1 / x) = pi / 2 - y" unfolding `tan y = x`[symmetric] tan_inverse using arctan_tan by auto
|
hoelzl@29740
|
3086 |
hence "arctan (1 / x) = sgn x * pi / 2 - arctan x" unfolding `y = arctan x` real_sgn_pos[OF `x > 0`] by auto
|
hoelzl@29740
|
3087 |
} note pos_y = this
|
hoelzl@29740
|
3088 |
|
hoelzl@29740
|
3089 |
show ?thesis
|
hoelzl@29740
|
3090 |
proof (cases "y > 0")
|
hoelzl@29740
|
3091 |
case True from pos_y[OF this `y < pi / 2` `y = arctan x` `tan y = x`] show ?thesis .
|
hoelzl@29740
|
3092 |
next
|
hoelzl@29740
|
3093 |
case False hence "y \<le> 0" by auto
|
hoelzl@29740
|
3094 |
moreover have "y \<noteq> 0"
|
hoelzl@29740
|
3095 |
proof (rule ccontr)
|
hoelzl@29740
|
3096 |
assume "\<not> y \<noteq> 0" hence "y = 0" by auto
|
hoelzl@29740
|
3097 |
have "x = 0" unfolding `tan y = x`[symmetric] `y = 0` tan_zero ..
|
hoelzl@29740
|
3098 |
thus False using `x \<noteq> 0` by auto
|
hoelzl@29740
|
3099 |
qed
|
hoelzl@29740
|
3100 |
ultimately have "y < 0" by auto
|
hoelzl@29740
|
3101 |
hence "0 < - y" and "-y < pi / 2" using `- (pi / 2) < y` by auto
|
hoelzl@29740
|
3102 |
moreover have "-y = arctan (-x)" unfolding arctan_minus `y = arctan x` ..
|
hoelzl@29740
|
3103 |
moreover have "tan (-y) = -x" unfolding tan_minus `tan y = x` ..
|
hoelzl@29740
|
3104 |
ultimately have "arctan (1 / -x) = sgn (-x) * pi / 2 - arctan (-x)" using pos_y by blast
|
hoelzl@29740
|
3105 |
hence "arctan (- (1 / x)) = - (sgn x * pi / 2 - arctan x)" unfolding arctan_minus[of x] divide_minus_right sgn_minus by auto
|
hoelzl@29740
|
3106 |
thus ?thesis unfolding arctan_minus neg_equal_iff_equal .
|
hoelzl@29740
|
3107 |
qed
|
hoelzl@29740
|
3108 |
qed
|
hoelzl@29740
|
3109 |
|
hoelzl@29740
|
3110 |
theorem pi_series: "pi / 4 = (\<Sum> k. (-1)^k * 1 / real (k*2+1))" (is "_ = ?SUM")
|
hoelzl@29740
|
3111 |
proof -
|
hoelzl@29740
|
3112 |
have "pi / 4 = arctan 1" using arctan1_eq_pi4 by auto
|
hoelzl@29740
|
3113 |
also have "\<dots> = ?SUM" using arctan_series[of 1] by auto
|
hoelzl@29740
|
3114 |
finally show ?thesis by auto
|
hoelzl@29740
|
3115 |
qed
|
paulson@15077
|
3116 |
|
huffman@22978
|
3117 |
subsection {* Existence of Polar Coordinates *}
|
paulson@15077
|
3118 |
|
huffman@22978
|
3119 |
lemma cos_x_y_le_one: "\<bar>x / sqrt (x\<twosuperior> + y\<twosuperior>)\<bar> \<le> 1"
|
huffman@22978
|
3120 |
apply (rule power2_le_imp_le [OF _ zero_le_one])
|
huffman@22978
|
3121 |
apply (simp add: abs_divide power_divide divide_le_eq not_sum_power2_lt_zero)
|
huffman@22976
|
3122 |
done
|
paulson@15077
|
3123 |
|
huffman@22978
|
3124 |
lemma cos_arccos_abs: "\<bar>y\<bar> \<le> 1 \<Longrightarrow> cos (arccos y) = y"
|
huffman@22978
|
3125 |
by (simp add: abs_le_iff)
|
paulson@15077
|
3126 |
|
huffman@23045
|
3127 |
lemma sin_arccos_abs: "\<bar>y\<bar> \<le> 1 \<Longrightarrow> sin (arccos y) = sqrt (1 - y\<twosuperior>)"
|
huffman@23045
|
3128 |
by (simp add: sin_arccos abs_le_iff)
|
paulson@15077
|
3129 |
|
huffman@22978
|
3130 |
lemmas cos_arccos_lemma1 = cos_arccos_abs [OF cos_x_y_le_one]
|
paulson@15077
|
3131 |
|
huffman@23045
|
3132 |
lemmas sin_arccos_lemma1 = sin_arccos_abs [OF cos_x_y_le_one]
|
paulson@15077
|
3133 |
|
paulson@15229
|
3134 |
lemma polar_ex1:
|
huffman@22978
|
3135 |
"0 < y ==> \<exists>r a. x = r * cos a & y = r * sin a"
|
paulson@15229
|
3136 |
apply (rule_tac x = "sqrt (x\<twosuperior> + y\<twosuperior>)" in exI)
|
huffman@22978
|
3137 |
apply (rule_tac x = "arccos (x / sqrt (x\<twosuperior> + y\<twosuperior>))" in exI)
|
huffman@22978
|
3138 |
apply (simp add: cos_arccos_lemma1)
|
huffman@23045
|
3139 |
apply (simp add: sin_arccos_lemma1)
|
huffman@23045
|
3140 |
apply (simp add: power_divide)
|
huffman@23045
|
3141 |
apply (simp add: real_sqrt_mult [symmetric])
|
huffman@23045
|
3142 |
apply (simp add: right_diff_distrib)
|
paulson@15077
|
3143 |
done
|
paulson@15077
|
3144 |
|
paulson@15229
|
3145 |
lemma polar_ex2:
|
huffman@22978
|
3146 |
"y < 0 ==> \<exists>r a. x = r * cos a & y = r * sin a"
|
huffman@22978
|
3147 |
apply (insert polar_ex1 [where x=x and y="-y"], simp, clarify)
|
paulson@15077
|
3148 |
apply (rule_tac x = r in exI)
|
huffman@22978
|
3149 |
apply (rule_tac x = "-a" in exI, simp)
|
paulson@15077
|
3150 |
done
|
paulson@15077
|
3151 |
|
paulson@15077
|
3152 |
lemma polar_Ex: "\<exists>r a. x = r * cos a & y = r * sin a"
|
huffman@22978
|
3153 |
apply (rule_tac x=0 and y=y in linorder_cases)
|
huffman@22978
|
3154 |
apply (erule polar_ex1)
|
huffman@22978
|
3155 |
apply (rule_tac x=x in exI, rule_tac x=0 in exI, simp)
|
huffman@22978
|
3156 |
apply (erule polar_ex2)
|
paulson@15077
|
3157 |
done
|
paulson@15077
|
3158 |
|
huffman@30019
|
3159 |
end
|