src/HOL/Transcendental.thy
author nipkow
Wed Jan 28 16:29:16 2009 +0100 (2009-01-28)
changeset 29667 53103fc8ffa3
parent 29171 5eff800a695f
child 29695 171146a93106
permissions -rw-r--r--
Replaced group_ and ring_simps by algebra_simps;
removed compare_rls - use algebra_simps now
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(*  Title       : Transcendental.thy
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    Author      : Jacques D. Fleuriot
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    Copyright   : 1998,1999 University of Cambridge
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                  1999,2001 University of Edinburgh
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    Conversion to Isar and new proofs by Lawrence C Paulson, 2004
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*)
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header{*Power Series, Transcendental Functions etc.*}
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theory Transcendental
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imports Fact Series Deriv NthRoot
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begin
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subsection {* Properties of Power Series *}
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lemma lemma_realpow_diff:
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  fixes y :: "'a::recpower"
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  shows "p \<le> n \<Longrightarrow> y ^ (Suc n - p) = (y ^ (n - p)) * y"
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proof -
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  assume "p \<le> n"
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  hence "Suc n - p = Suc (n - p)" by (rule Suc_diff_le)
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  thus ?thesis by (simp add: power_Suc power_commutes)
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qed
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lemma lemma_realpow_diff_sumr:
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  fixes y :: "'a::{recpower,comm_semiring_0}" shows
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     "(\<Sum>p=0..<Suc n. (x ^ p) * y ^ (Suc n - p)) =  
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      y * (\<Sum>p=0..<Suc n. (x ^ p) * y ^ (n - p))"
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by (simp add: setsum_right_distrib lemma_realpow_diff mult_ac
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         del: setsum_op_ivl_Suc cong: strong_setsum_cong)
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lemma lemma_realpow_diff_sumr2:
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  fixes y :: "'a::{recpower,comm_ring}" shows
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     "x ^ (Suc n) - y ^ (Suc n) =  
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      (x - y) * (\<Sum>p=0..<Suc n. (x ^ p) * y ^ (n - p))"
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apply (induct n, simp add: power_Suc)
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apply (simp add: power_Suc del: setsum_op_ivl_Suc)
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apply (subst setsum_op_ivl_Suc)
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apply (subst lemma_realpow_diff_sumr)
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apply (simp add: right_distrib del: setsum_op_ivl_Suc)
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apply (subst mult_left_commute [where a="x - y"])
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apply (erule subst)
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apply (simp add: power_Suc algebra_simps)
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done
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lemma lemma_realpow_rev_sumr:
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     "(\<Sum>p=0..<Suc n. (x ^ p) * (y ^ (n - p))) =  
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      (\<Sum>p=0..<Suc n. (x ^ (n - p)) * (y ^ p))"
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apply (rule setsum_reindex_cong [where f="\<lambda>i. n - i"])
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apply (rule inj_onI, simp)
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apply auto
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apply (rule_tac x="n - x" in image_eqI, simp, simp)
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done
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text{*Power series has a `circle` of convergence, i.e. if it sums for @{term
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x}, then it sums absolutely for @{term z} with @{term "\<bar>z\<bar> < \<bar>x\<bar>"}.*}
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lemma powser_insidea:
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  fixes x z :: "'a::{real_normed_field,banach,recpower}"
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  assumes 1: "summable (\<lambda>n. f n * x ^ n)"
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  assumes 2: "norm z < norm x"
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  shows "summable (\<lambda>n. norm (f n * z ^ n))"
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proof -
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  from 2 have x_neq_0: "x \<noteq> 0" by clarsimp
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  from 1 have "(\<lambda>n. f n * x ^ n) ----> 0"
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    by (rule summable_LIMSEQ_zero)
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  hence "convergent (\<lambda>n. f n * x ^ n)"
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    by (rule convergentI)
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  hence "Cauchy (\<lambda>n. f n * x ^ n)"
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    by (simp add: Cauchy_convergent_iff)
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  hence "Bseq (\<lambda>n. f n * x ^ n)"
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    by (rule Cauchy_Bseq)
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  then obtain K where 3: "0 < K" and 4: "\<forall>n. norm (f n * x ^ n) \<le> K"
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    by (simp add: Bseq_def, safe)
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  have "\<exists>N. \<forall>n\<ge>N. norm (norm (f n * z ^ n)) \<le>
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                   K * norm (z ^ n) * inverse (norm (x ^ n))"
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  proof (intro exI allI impI)
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    fix n::nat assume "0 \<le> n"
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    have "norm (norm (f n * z ^ n)) * norm (x ^ n) =
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          norm (f n * x ^ n) * norm (z ^ n)"
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      by (simp add: norm_mult abs_mult)
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    also have "\<dots> \<le> K * norm (z ^ n)"
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      by (simp only: mult_right_mono 4 norm_ge_zero)
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    also have "\<dots> = K * norm (z ^ n) * (inverse (norm (x ^ n)) * norm (x ^ n))"
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      by (simp add: x_neq_0)
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    also have "\<dots> = K * norm (z ^ n) * inverse (norm (x ^ n)) * norm (x ^ n)"
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      by (simp only: mult_assoc)
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    finally show "norm (norm (f n * z ^ n)) \<le>
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                  K * norm (z ^ n) * inverse (norm (x ^ n))"
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      by (simp add: mult_le_cancel_right x_neq_0)
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  qed
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  moreover have "summable (\<lambda>n. K * norm (z ^ n) * inverse (norm (x ^ n)))"
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  proof -
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    from 2 have "norm (norm (z * inverse x)) < 1"
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      using x_neq_0
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      by (simp add: nonzero_norm_divide divide_inverse [symmetric])
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    hence "summable (\<lambda>n. norm (z * inverse x) ^ n)"
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      by (rule summable_geometric)
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    hence "summable (\<lambda>n. K * norm (z * inverse x) ^ n)"
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      by (rule summable_mult)
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    thus "summable (\<lambda>n. K * norm (z ^ n) * inverse (norm (x ^ n)))"
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      using x_neq_0
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      by (simp add: norm_mult nonzero_norm_inverse power_mult_distrib
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                    power_inverse norm_power mult_assoc)
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  qed
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  ultimately show "summable (\<lambda>n. norm (f n * z ^ n))"
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    by (rule summable_comparison_test)
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qed
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lemma powser_inside:
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  fixes f :: "nat \<Rightarrow> 'a::{real_normed_field,banach,recpower}" shows
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     "[| summable (%n. f(n) * (x ^ n)); norm z < norm x |]  
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      ==> summable (%n. f(n) * (z ^ n))"
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by (rule powser_insidea [THEN summable_norm_cancel])
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subsection {* Term-by-Term Differentiability of Power Series *}
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definition
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  diffs :: "(nat => 'a::ring_1) => nat => 'a" where
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  "diffs c = (%n. of_nat (Suc n) * c(Suc n))"
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text{*Lemma about distributing negation over it*}
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lemma diffs_minus: "diffs (%n. - c n) = (%n. - diffs c n)"
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by (simp add: diffs_def)
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lemma sums_Suc_imp:
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  assumes f: "f 0 = 0"
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  shows "(\<lambda>n. f (Suc n)) sums s \<Longrightarrow> (\<lambda>n. f n) sums s"
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unfolding sums_def
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apply (rule LIMSEQ_imp_Suc)
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apply (subst setsum_shift_lb_Suc0_0_upt [where f=f, OF f, symmetric])
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apply (simp only: setsum_shift_bounds_Suc_ivl)
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done
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lemma diffs_equiv:
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     "summable (%n. (diffs c)(n) * (x ^ n)) ==>  
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      (%n. of_nat n * c(n) * (x ^ (n - Suc 0))) sums  
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         (\<Sum>n. (diffs c)(n) * (x ^ n))"
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unfolding diffs_def
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apply (drule summable_sums)
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apply (rule sums_Suc_imp, simp_all)
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done
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lemma lemma_termdiff1:
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  fixes z :: "'a :: {recpower,comm_ring}" shows
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  "(\<Sum>p=0..<m. (((z + h) ^ (m - p)) * (z ^ p)) - (z ^ m)) =  
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   (\<Sum>p=0..<m. (z ^ p) * (((z + h) ^ (m - p)) - (z ^ (m - p))))"
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by(auto simp add: algebra_simps power_add [symmetric] cong: strong_setsum_cong)
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lemma sumr_diff_mult_const2:
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  "setsum f {0..<n} - of_nat n * (r::'a::ring_1) = (\<Sum>i = 0..<n. f i - r)"
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by (simp add: setsum_subtractf)
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lemma lemma_termdiff2:
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  fixes h :: "'a :: {recpower,field}"
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  assumes h: "h \<noteq> 0" shows
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  "((z + h) ^ n - z ^ n) / h - of_nat n * z ^ (n - Suc 0) =
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   h * (\<Sum>p=0..< n - Suc 0. \<Sum>q=0..< n - Suc 0 - p.
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        (z + h) ^ q * z ^ (n - 2 - q))" (is "?lhs = ?rhs")
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apply (subgoal_tac "h * ?lhs = h * ?rhs", simp add: h)
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apply (simp add: right_diff_distrib diff_divide_distrib h)
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apply (simp add: mult_assoc [symmetric])
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apply (cases "n", simp)
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apply (simp add: lemma_realpow_diff_sumr2 h
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                 right_diff_distrib [symmetric] mult_assoc
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            del: realpow_Suc setsum_op_ivl_Suc of_nat_Suc)
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apply (subst lemma_realpow_rev_sumr)
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apply (subst sumr_diff_mult_const2)
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apply simp
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apply (simp only: lemma_termdiff1 setsum_right_distrib)
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apply (rule setsum_cong [OF refl])
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apply (simp add: diff_minus [symmetric] less_iff_Suc_add)
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apply (clarify)
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apply (simp add: setsum_right_distrib lemma_realpow_diff_sumr2 mult_ac
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            del: setsum_op_ivl_Suc realpow_Suc)
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apply (subst mult_assoc [symmetric], subst power_add [symmetric])
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apply (simp add: mult_ac)
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done
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lemma real_setsum_nat_ivl_bounded2:
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  fixes K :: "'a::ordered_semidom"
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  assumes f: "\<And>p::nat. p < n \<Longrightarrow> f p \<le> K"
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  assumes K: "0 \<le> K"
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  shows "setsum f {0..<n-k} \<le> of_nat n * K"
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apply (rule order_trans [OF setsum_mono])
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apply (rule f, simp)
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apply (simp add: mult_right_mono K)
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done
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lemma lemma_termdiff3:
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  fixes h z :: "'a::{real_normed_field,recpower}"
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  assumes 1: "h \<noteq> 0"
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  assumes 2: "norm z \<le> K"
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  assumes 3: "norm (z + h) \<le> K"
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  shows "norm (((z + h) ^ n - z ^ n) / h - of_nat n * z ^ (n - Suc 0))
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          \<le> of_nat n * of_nat (n - Suc 0) * K ^ (n - 2) * norm h"
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proof -
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  have "norm (((z + h) ^ n - z ^ n) / h - of_nat n * z ^ (n - Suc 0)) =
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        norm (\<Sum>p = 0..<n - Suc 0. \<Sum>q = 0..<n - Suc 0 - p.
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          (z + h) ^ q * z ^ (n - 2 - q)) * norm h"
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    apply (subst lemma_termdiff2 [OF 1])
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    apply (subst norm_mult)
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    apply (rule mult_commute)
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    done
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  also have "\<dots> \<le> of_nat n * (of_nat (n - Suc 0) * K ^ (n - 2)) * norm h"
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  proof (rule mult_right_mono [OF _ norm_ge_zero])
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    from norm_ge_zero 2 have K: "0 \<le> K" by (rule order_trans)
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    have le_Kn: "\<And>i j n. i + j = n \<Longrightarrow> norm ((z + h) ^ i * z ^ j) \<le> K ^ n"
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      apply (erule subst)
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      apply (simp only: norm_mult norm_power power_add)
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      apply (intro mult_mono power_mono 2 3 norm_ge_zero zero_le_power K)
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      done
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    show "norm (\<Sum>p = 0..<n - Suc 0. \<Sum>q = 0..<n - Suc 0 - p.
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              (z + h) ^ q * z ^ (n - 2 - q))
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          \<le> of_nat n * (of_nat (n - Suc 0) * K ^ (n - 2))"
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      apply (intro
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         order_trans [OF norm_setsum]
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         real_setsum_nat_ivl_bounded2
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         mult_nonneg_nonneg
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         zero_le_imp_of_nat
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         zero_le_power K)
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      apply (rule le_Kn, simp)
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      done
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  qed
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  also have "\<dots> = of_nat n * of_nat (n - Suc 0) * K ^ (n - 2) * norm h"
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    by (simp only: mult_assoc)
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  finally show ?thesis .
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qed
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lemma lemma_termdiff4:
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  fixes f :: "'a::{real_normed_field,recpower} \<Rightarrow>
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              'b::real_normed_vector"
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  assumes k: "0 < (k::real)"
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  assumes le: "\<And>h. \<lbrakk>h \<noteq> 0; norm h < k\<rbrakk> \<Longrightarrow> norm (f h) \<le> K * norm h"
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  shows "f -- 0 --> 0"
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unfolding LIM_def diff_0_right
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proof (safe)
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  let ?h = "of_real (k / 2)::'a"
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  have "?h \<noteq> 0" and "norm ?h < k" using k by simp_all
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  hence "norm (f ?h) \<le> K * norm ?h" by (rule le)
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  hence "0 \<le> K * norm ?h" by (rule order_trans [OF norm_ge_zero])
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  hence zero_le_K: "0 \<le> K" using k by (simp add: zero_le_mult_iff)
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  fix r::real assume r: "0 < r"
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  show "\<exists>s. 0 < s \<and> (\<forall>x. x \<noteq> 0 \<and> norm x < s \<longrightarrow> norm (f x) < r)"
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  proof (cases)
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    assume "K = 0"
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    with k r le have "0 < k \<and> (\<forall>x. x \<noteq> 0 \<and> norm x < k \<longrightarrow> norm (f x) < r)"
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      by simp
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    thus "\<exists>s. 0 < s \<and> (\<forall>x. x \<noteq> 0 \<and> norm x < s \<longrightarrow> norm (f x) < r)" ..
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  next
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    assume K_neq_zero: "K \<noteq> 0"
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    with zero_le_K have K: "0 < K" by simp
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    show "\<exists>s. 0 < s \<and> (\<forall>x. x \<noteq> 0 \<and> norm x < s \<longrightarrow> norm (f x) < r)"
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    proof (rule exI, safe)
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      from k r K show "0 < min k (r * inverse K / 2)"
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        by (simp add: mult_pos_pos positive_imp_inverse_positive)
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    next
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      fix x::'a
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      assume x1: "x \<noteq> 0" and x2: "norm x < min k (r * inverse K / 2)"
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      from x2 have x3: "norm x < k" and x4: "norm x < r * inverse K / 2"
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        by simp_all
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      from x1 x3 le have "norm (f x) \<le> K * norm x" by simp
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      also from x4 K have "K * norm x < K * (r * inverse K / 2)"
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        by (rule mult_strict_left_mono)
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      also have "\<dots> = r / 2"
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        using K_neq_zero by simp
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      also have "r / 2 < r"
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        using r by simp
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      finally show "norm (f x) < r" .
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    qed
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  qed
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qed
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lemma lemma_termdiff5:
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  fixes g :: "'a::{recpower,real_normed_field} \<Rightarrow>
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              nat \<Rightarrow> 'b::banach"
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  assumes k: "0 < (k::real)"
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  assumes f: "summable f"
huffman@23082
   281
  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
   282
  shows "(\<lambda>h. suminf (g h)) -- 0 --> 0"
huffman@20860
   283
proof (rule lemma_termdiff4 [OF k])
huffman@23082
   284
  fix h::'a assume "h \<noteq> 0" and "norm h < k"
huffman@23082
   285
  hence A: "\<forall>n. norm (g h n) \<le> f n * norm h"
huffman@20860
   286
    by (simp add: le)
huffman@23082
   287
  hence "\<exists>N. \<forall>n\<ge>N. norm (norm (g h n)) \<le> f n * norm h"
huffman@20860
   288
    by simp
huffman@23082
   289
  moreover from f have B: "summable (\<lambda>n. f n * norm h)"
huffman@20860
   290
    by (rule summable_mult2)
huffman@23082
   291
  ultimately have C: "summable (\<lambda>n. norm (g h n))"
huffman@20860
   292
    by (rule summable_comparison_test)
huffman@23082
   293
  hence "norm (suminf (g h)) \<le> (\<Sum>n. norm (g h n))"
huffman@23082
   294
    by (rule summable_norm)
huffman@23082
   295
  also from A C B have "(\<Sum>n. norm (g h n)) \<le> (\<Sum>n. f n * norm h)"
huffman@20860
   296
    by (rule summable_le)
huffman@23082
   297
  also from f have "(\<Sum>n. f n * norm h) = suminf f * norm h"
huffman@20860
   298
    by (rule suminf_mult2 [symmetric])
huffman@23082
   299
  finally show "norm (suminf (g h)) \<le> suminf f * norm h" .
huffman@20860
   300
qed
paulson@15077
   301
paulson@15077
   302
paulson@15077
   303
text{* FIXME: Long proofs*}
paulson@15077
   304
paulson@15077
   305
lemma termdiffs_aux:
huffman@23112
   306
  fixes x :: "'a::{recpower,real_normed_field,banach}"
huffman@20849
   307
  assumes 1: "summable (\<lambda>n. diffs (diffs c) n * K ^ n)"
huffman@23082
   308
  assumes 2: "norm x < norm K"
huffman@20860
   309
  shows "(\<lambda>h. \<Sum>n. c n * (((x + h) ^ n - x ^ n) / h
huffman@23082
   310
             - of_nat n * x ^ (n - Suc 0))) -- 0 --> 0"
huffman@20849
   311
proof -
huffman@20860
   312
  from dense [OF 2]
huffman@23082
   313
  obtain r where r1: "norm x < r" and r2: "r < norm K" by fast
huffman@23082
   314
  from norm_ge_zero r1 have r: "0 < r"
huffman@20860
   315
    by (rule order_le_less_trans)
huffman@20860
   316
  hence r_neq_0: "r \<noteq> 0" by simp
huffman@20860
   317
  show ?thesis
huffman@20849
   318
  proof (rule lemma_termdiff5)
huffman@23082
   319
    show "0 < r - norm x" using r1 by simp
huffman@20849
   320
  next
huffman@23082
   321
    from r r2 have "norm (of_real r::'a) < norm K"
huffman@23082
   322
      by simp
huffman@23082
   323
    with 1 have "summable (\<lambda>n. norm (diffs (diffs c) n * (of_real r ^ n)))"
huffman@20860
   324
      by (rule powser_insidea)
huffman@23082
   325
    hence "summable (\<lambda>n. diffs (diffs (\<lambda>n. norm (c n))) n * r ^ n)"
huffman@23082
   326
      using r
huffman@23082
   327
      by (simp add: diffs_def norm_mult norm_power del: of_nat_Suc)
huffman@23082
   328
    hence "summable (\<lambda>n. of_nat n * diffs (\<lambda>n. norm (c n)) n * r ^ (n - Suc 0))"
huffman@20860
   329
      by (rule diffs_equiv [THEN sums_summable])
huffman@23082
   330
    also have "(\<lambda>n. of_nat n * diffs (\<lambda>n. norm (c n)) n * r ^ (n - Suc 0))
huffman@23082
   331
      = (\<lambda>n. diffs (%m. of_nat (m - Suc 0) * norm (c m) * inverse r) n * (r ^ n))"
huffman@20849
   332
      apply (rule ext)
huffman@20849
   333
      apply (simp add: diffs_def)
huffman@20849
   334
      apply (case_tac n, simp_all add: r_neq_0)
huffman@20849
   335
      done
huffman@20860
   336
    finally have "summable 
huffman@23082
   337
      (\<lambda>n. of_nat n * (of_nat (n - Suc 0) * norm (c n) * inverse r) * r ^ (n - Suc 0))"
huffman@20860
   338
      by (rule diffs_equiv [THEN sums_summable])
huffman@20860
   339
    also have
huffman@23082
   340
      "(\<lambda>n. of_nat n * (of_nat (n - Suc 0) * norm (c n) * inverse r) *
huffman@20860
   341
           r ^ (n - Suc 0)) =
huffman@23082
   342
       (\<lambda>n. norm (c n) * of_nat n * of_nat (n - Suc 0) * r ^ (n - 2))"
huffman@20849
   343
      apply (rule ext)
huffman@20849
   344
      apply (case_tac "n", simp)
huffman@20849
   345
      apply (case_tac "nat", simp)
huffman@20849
   346
      apply (simp add: r_neq_0)
huffman@20849
   347
      done
huffman@20860
   348
    finally show
huffman@23082
   349
      "summable (\<lambda>n. norm (c n) * of_nat n * of_nat (n - Suc 0) * r ^ (n - 2))" .
huffman@20849
   350
  next
huffman@23082
   351
    fix h::'a and n::nat
huffman@20860
   352
    assume h: "h \<noteq> 0"
huffman@23082
   353
    assume "norm h < r - norm x"
huffman@23082
   354
    hence "norm x + norm h < r" by simp
huffman@23082
   355
    with norm_triangle_ineq have xh: "norm (x + h) < r"
huffman@20860
   356
      by (rule order_le_less_trans)
huffman@23082
   357
    show "norm (c n * (((x + h) ^ n - x ^ n) / h - of_nat n * x ^ (n - Suc 0)))
huffman@23082
   358
          \<le> norm (c n) * of_nat n * of_nat (n - Suc 0) * r ^ (n - 2) * norm h"
huffman@23082
   359
      apply (simp only: norm_mult mult_assoc)
huffman@23082
   360
      apply (rule mult_left_mono [OF _ norm_ge_zero])
huffman@20860
   361
      apply (simp (no_asm) add: mult_assoc [symmetric])
huffman@20860
   362
      apply (rule lemma_termdiff3)
huffman@20860
   363
      apply (rule h)
huffman@20860
   364
      apply (rule r1 [THEN order_less_imp_le])
huffman@20860
   365
      apply (rule xh [THEN order_less_imp_le])
huffman@20860
   366
      done
huffman@20849
   367
  qed
huffman@20849
   368
qed
webertj@20217
   369
huffman@20860
   370
lemma termdiffs:
huffman@23112
   371
  fixes K x :: "'a::{recpower,real_normed_field,banach}"
huffman@20860
   372
  assumes 1: "summable (\<lambda>n. c n * K ^ n)"
huffman@20860
   373
  assumes 2: "summable (\<lambda>n. (diffs c) n * K ^ n)"
huffman@20860
   374
  assumes 3: "summable (\<lambda>n. (diffs (diffs c)) n * K ^ n)"
huffman@23082
   375
  assumes 4: "norm x < norm K"
huffman@20860
   376
  shows "DERIV (\<lambda>x. \<Sum>n. c n * x ^ n) x :> (\<Sum>n. (diffs c) n * x ^ n)"
huffman@29163
   377
unfolding deriv_def
huffman@29163
   378
proof (rule LIM_zero_cancel)
huffman@20860
   379
  show "(\<lambda>h. (suminf (\<lambda>n. c n * (x + h) ^ n) - suminf (\<lambda>n. c n * x ^ n)) / h
huffman@20860
   380
            - suminf (\<lambda>n. diffs c n * x ^ n)) -- 0 --> 0"
huffman@20860
   381
  proof (rule LIM_equal2)
huffman@29163
   382
    show "0 < norm K - norm x" using 4 by (simp add: less_diff_eq)
huffman@20860
   383
  next
huffman@23082
   384
    fix h :: 'a
huffman@20860
   385
    assume "h \<noteq> 0"
huffman@23082
   386
    assume "norm (h - 0) < norm K - norm x"
huffman@23082
   387
    hence "norm x + norm h < norm K" by simp
huffman@23082
   388
    hence 5: "norm (x + h) < norm K"
huffman@23082
   389
      by (rule norm_triangle_ineq [THEN order_le_less_trans])
huffman@20860
   390
    have A: "summable (\<lambda>n. c n * x ^ n)"
huffman@20860
   391
      by (rule powser_inside [OF 1 4])
huffman@20860
   392
    have B: "summable (\<lambda>n. c n * (x + h) ^ n)"
huffman@20860
   393
      by (rule powser_inside [OF 1 5])
huffman@20860
   394
    have C: "summable (\<lambda>n. diffs c n * x ^ n)"
huffman@20860
   395
      by (rule powser_inside [OF 2 4])
huffman@20860
   396
    show "((\<Sum>n. c n * (x + h) ^ n) - (\<Sum>n. c n * x ^ n)) / h
huffman@20860
   397
             - (\<Sum>n. diffs c n * x ^ n) = 
huffman@23082
   398
          (\<Sum>n. c n * (((x + h) ^ n - x ^ n) / h - of_nat n * x ^ (n - Suc 0)))"
huffman@20860
   399
      apply (subst sums_unique [OF diffs_equiv [OF C]])
huffman@20860
   400
      apply (subst suminf_diff [OF B A])
huffman@20860
   401
      apply (subst suminf_divide [symmetric])
huffman@20860
   402
      apply (rule summable_diff [OF B A])
huffman@20860
   403
      apply (subst suminf_diff)
huffman@20860
   404
      apply (rule summable_divide)
huffman@20860
   405
      apply (rule summable_diff [OF B A])
huffman@20860
   406
      apply (rule sums_summable [OF diffs_equiv [OF C]])
huffman@29163
   407
      apply (rule arg_cong [where f="suminf"], rule ext)
nipkow@29667
   408
      apply (simp add: algebra_simps)
huffman@20860
   409
      done
huffman@20860
   410
  next
huffman@20860
   411
    show "(\<lambda>h. \<Sum>n. c n * (((x + h) ^ n - x ^ n) / h -
huffman@23082
   412
               of_nat n * x ^ (n - Suc 0))) -- 0 --> 0"
huffman@20860
   413
        by (rule termdiffs_aux [OF 3 4])
huffman@20860
   414
  qed
huffman@20860
   415
qed
huffman@20860
   416
paulson@15077
   417
huffman@29164
   418
subsection {* Exponential Function *}
huffman@23043
   419
huffman@23043
   420
definition
huffman@23115
   421
  exp :: "'a \<Rightarrow> 'a::{recpower,real_normed_field,banach}" where
haftmann@25062
   422
  "exp x = (\<Sum>n. x ^ n /\<^sub>R real (fact n))"
huffman@23043
   423
huffman@23115
   424
lemma summable_exp_generic:
huffman@23115
   425
  fixes x :: "'a::{real_normed_algebra_1,recpower,banach}"
haftmann@25062
   426
  defines S_def: "S \<equiv> \<lambda>n. x ^ n /\<^sub>R real (fact n)"
huffman@23115
   427
  shows "summable S"
huffman@23115
   428
proof -
haftmann@25062
   429
  have S_Suc: "\<And>n. S (Suc n) = (x * S n) /\<^sub>R real (Suc n)"
huffman@23115
   430
    unfolding S_def by (simp add: power_Suc del: mult_Suc)
huffman@23115
   431
  obtain r :: real where r0: "0 < r" and r1: "r < 1"
huffman@23115
   432
    using dense [OF zero_less_one] by fast
huffman@23115
   433
  obtain N :: nat where N: "norm x < real N * r"
huffman@23115
   434
    using reals_Archimedean3 [OF r0] by fast
huffman@23115
   435
  from r1 show ?thesis
huffman@23115
   436
  proof (rule ratio_test [rule_format])
huffman@23115
   437
    fix n :: nat
huffman@23115
   438
    assume n: "N \<le> n"
huffman@23115
   439
    have "norm x \<le> real N * r"
huffman@23115
   440
      using N by (rule order_less_imp_le)
huffman@23115
   441
    also have "real N * r \<le> real (Suc n) * r"
huffman@23115
   442
      using r0 n by (simp add: mult_right_mono)
huffman@23115
   443
    finally have "norm x * norm (S n) \<le> real (Suc n) * r * norm (S n)"
huffman@23115
   444
      using norm_ge_zero by (rule mult_right_mono)
huffman@23115
   445
    hence "norm (x * S n) \<le> real (Suc n) * r * norm (S n)"
huffman@23115
   446
      by (rule order_trans [OF norm_mult_ineq])
huffman@23115
   447
    hence "norm (x * S n) / real (Suc n) \<le> r * norm (S n)"
huffman@23115
   448
      by (simp add: pos_divide_le_eq mult_ac)
huffman@23115
   449
    thus "norm (S (Suc n)) \<le> r * norm (S n)"
huffman@23115
   450
      by (simp add: S_Suc norm_scaleR inverse_eq_divide)
huffman@23115
   451
  qed
huffman@23115
   452
qed
huffman@23115
   453
huffman@23115
   454
lemma summable_norm_exp:
huffman@23115
   455
  fixes x :: "'a::{real_normed_algebra_1,recpower,banach}"
haftmann@25062
   456
  shows "summable (\<lambda>n. norm (x ^ n /\<^sub>R real (fact n)))"
huffman@23115
   457
proof (rule summable_norm_comparison_test [OF exI, rule_format])
haftmann@25062
   458
  show "summable (\<lambda>n. norm x ^ n /\<^sub>R real (fact n))"
huffman@23115
   459
    by (rule summable_exp_generic)
huffman@23115
   460
next
haftmann@25062
   461
  fix n show "norm (x ^ n /\<^sub>R real (fact n)) \<le> norm x ^ n /\<^sub>R real (fact n)"
huffman@23115
   462
    by (simp add: norm_scaleR norm_power_ineq)
huffman@23115
   463
qed
huffman@23115
   464
huffman@23043
   465
lemma summable_exp: "summable (%n. inverse (real (fact n)) * x ^ n)"
huffman@23115
   466
by (insert summable_exp_generic [where x=x], simp)
huffman@23043
   467
haftmann@25062
   468
lemma exp_converges: "(\<lambda>n. x ^ n /\<^sub>R real (fact n)) sums exp x"
huffman@23115
   469
unfolding exp_def by (rule summable_exp_generic [THEN summable_sums])
huffman@23043
   470
huffman@23043
   471
paulson@15077
   472
lemma exp_fdiffs: 
paulson@15077
   473
      "diffs (%n. inverse(real (fact n))) = (%n. inverse(real (fact n)))"
huffman@23431
   474
by (simp add: diffs_def mult_assoc [symmetric] real_of_nat_def of_nat_mult
huffman@23082
   475
         del: mult_Suc of_nat_Suc)
paulson@15077
   476
huffman@23115
   477
lemma diffs_of_real: "diffs (\<lambda>n. of_real (f n)) = (\<lambda>n. of_real (diffs f n))"
huffman@23115
   478
by (simp add: diffs_def)
huffman@23115
   479
haftmann@25062
   480
lemma lemma_exp_ext: "exp = (\<lambda>x. \<Sum>n. x ^ n /\<^sub>R real (fact n))"
paulson@15077
   481
by (auto intro!: ext simp add: exp_def)
paulson@15077
   482
paulson@15077
   483
lemma DERIV_exp [simp]: "DERIV exp x :> exp(x)"
paulson@15229
   484
apply (simp add: exp_def)
paulson@15077
   485
apply (subst lemma_exp_ext)
huffman@23115
   486
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
   487
apply (rule_tac [2] K = "of_real (1 + norm x)" in termdiffs)
huffman@23115
   488
apply (simp_all only: diffs_of_real scaleR_conv_of_real exp_fdiffs)
huffman@23115
   489
apply (rule exp_converges [THEN sums_summable, unfolded scaleR_conv_of_real])+
huffman@23115
   490
apply (simp del: of_real_add)
paulson@15077
   491
done
paulson@15077
   492
huffman@23045
   493
lemma isCont_exp [simp]: "isCont exp x"
huffman@23045
   494
by (rule DERIV_exp [THEN DERIV_isCont])
huffman@23045
   495
huffman@23045
   496
huffman@29167
   497
subsubsection {* Properties of the Exponential Function *}
paulson@15077
   498
huffman@23278
   499
lemma powser_zero:
huffman@23278
   500
  fixes f :: "nat \<Rightarrow> 'a::{real_normed_algebra_1,recpower}"
huffman@23278
   501
  shows "(\<Sum>n. f n * 0 ^ n) = f 0"
paulson@15077
   502
proof -
huffman@23278
   503
  have "(\<Sum>n = 0..<1. f n * 0 ^ n) = (\<Sum>n. f n * 0 ^ n)"
huffman@23115
   504
    by (rule sums_unique [OF series_zero], simp add: power_0_left)
huffman@23278
   505
  thus ?thesis by simp
paulson@15077
   506
qed
paulson@15077
   507
huffman@23278
   508
lemma exp_zero [simp]: "exp 0 = 1"
huffman@23278
   509
unfolding exp_def by (simp add: scaleR_conv_of_real powser_zero)
huffman@23278
   510
huffman@23115
   511
lemma setsum_cl_ivl_Suc2:
huffman@23115
   512
  "(\<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
   513
by (simp add: setsum_head_Suc setsum_shift_bounds_cl_Suc_ivl
huffman@23115
   514
         del: setsum_cl_ivl_Suc)
huffman@23115
   515
huffman@23115
   516
lemma exp_series_add:
huffman@23115
   517
  fixes x y :: "'a::{real_field,recpower}"
haftmann@25062
   518
  defines S_def: "S \<equiv> \<lambda>x n. x ^ n /\<^sub>R real (fact n)"
huffman@23115
   519
  shows "S (x + y) n = (\<Sum>i=0..n. S x i * S y (n - i))"
huffman@23115
   520
proof (induct n)
huffman@23115
   521
  case 0
huffman@23115
   522
  show ?case
huffman@23115
   523
    unfolding S_def by simp
huffman@23115
   524
next
huffman@23115
   525
  case (Suc n)
haftmann@25062
   526
  have S_Suc: "\<And>x n. S x (Suc n) = (x * S x n) /\<^sub>R real (Suc n)"
huffman@23115
   527
    unfolding S_def by (simp add: power_Suc del: mult_Suc)
haftmann@25062
   528
  hence times_S: "\<And>x n. x * S x n = real (Suc n) *\<^sub>R S x (Suc n)"
huffman@23115
   529
    by simp
huffman@23115
   530
haftmann@25062
   531
  have "real (Suc n) *\<^sub>R S (x + y) (Suc n) = (x + y) * S (x + y) n"
huffman@23115
   532
    by (simp only: times_S)
huffman@23115
   533
  also have "\<dots> = (x + y) * (\<Sum>i=0..n. S x i * S y (n-i))"
huffman@23115
   534
    by (simp only: Suc)
huffman@23115
   535
  also have "\<dots> = x * (\<Sum>i=0..n. S x i * S y (n-i))
huffman@23115
   536
                + y * (\<Sum>i=0..n. S x i * S y (n-i))"
huffman@23115
   537
    by (rule left_distrib)
huffman@23115
   538
  also have "\<dots> = (\<Sum>i=0..n. (x * S x i) * S y (n-i))
huffman@23115
   539
                + (\<Sum>i=0..n. S x i * (y * S y (n-i)))"
huffman@23115
   540
    by (simp only: setsum_right_distrib mult_ac)
haftmann@25062
   541
  also have "\<dots> = (\<Sum>i=0..n. real (Suc i) *\<^sub>R (S x (Suc i) * S y (n-i)))
haftmann@25062
   542
                + (\<Sum>i=0..n. real (Suc n-i) *\<^sub>R (S x i * S y (Suc n-i)))"
huffman@23115
   543
    by (simp add: times_S Suc_diff_le)
haftmann@25062
   544
  also have "(\<Sum>i=0..n. real (Suc i) *\<^sub>R (S x (Suc i) * S y (n-i))) =
haftmann@25062
   545
             (\<Sum>i=0..Suc n. real i *\<^sub>R (S x i * S y (Suc n-i)))"
huffman@23115
   546
    by (subst setsum_cl_ivl_Suc2, simp)
haftmann@25062
   547
  also have "(\<Sum>i=0..n. real (Suc n-i) *\<^sub>R (S x i * S y (Suc n-i))) =
haftmann@25062
   548
             (\<Sum>i=0..Suc n. real (Suc n-i) *\<^sub>R (S x i * S y (Suc n-i)))"
huffman@23115
   549
    by (subst setsum_cl_ivl_Suc, simp)
haftmann@25062
   550
  also have "(\<Sum>i=0..Suc n. real i *\<^sub>R (S x i * S y (Suc n-i))) +
haftmann@25062
   551
             (\<Sum>i=0..Suc n. real (Suc n-i) *\<^sub>R (S x i * S y (Suc n-i))) =
haftmann@25062
   552
             (\<Sum>i=0..Suc n. real (Suc n) *\<^sub>R (S x i * S y (Suc n-i)))"
huffman@23115
   553
    by (simp only: setsum_addf [symmetric] scaleR_left_distrib [symmetric]
huffman@23115
   554
              real_of_nat_add [symmetric], simp)
haftmann@25062
   555
  also have "\<dots> = real (Suc n) *\<^sub>R (\<Sum>i=0..Suc n. S x i * S y (Suc n-i))"
huffman@23127
   556
    by (simp only: scaleR_right.setsum)
huffman@23115
   557
  finally show
huffman@23115
   558
    "S (x + y) (Suc n) = (\<Sum>i=0..Suc n. S x i * S y (Suc n - i))"
huffman@23115
   559
    by (simp add: scaleR_cancel_left del: setsum_cl_ivl_Suc)
huffman@23115
   560
qed
huffman@23115
   561
huffman@23115
   562
lemma exp_add: "exp (x + y) = exp x * exp y"
huffman@23115
   563
unfolding exp_def
huffman@23115
   564
by (simp only: Cauchy_product summable_norm_exp exp_series_add)
huffman@23115
   565
huffman@29170
   566
lemma mult_exp_exp: "exp x * exp y = exp (x + y)"
huffman@29170
   567
by (rule exp_add [symmetric])
huffman@29170
   568
huffman@23241
   569
lemma exp_of_real: "exp (of_real x) = of_real (exp x)"
huffman@23241
   570
unfolding exp_def
huffman@23241
   571
apply (subst of_real.suminf)
huffman@23241
   572
apply (rule summable_exp_generic)
huffman@23241
   573
apply (simp add: scaleR_conv_of_real)
huffman@23241
   574
done
huffman@23241
   575
huffman@29170
   576
lemma exp_not_eq_zero [simp]: "exp x \<noteq> 0"
huffman@29170
   577
proof
huffman@29170
   578
  have "exp x * exp (- x) = 1" by (simp add: mult_exp_exp)
huffman@29170
   579
  also assume "exp x = 0"
huffman@29170
   580
  finally show "False" by simp
paulson@15077
   581
qed
paulson@15077
   582
huffman@29170
   583
lemma exp_minus: "exp (- x) = inverse (exp x)"
huffman@29170
   584
by (rule inverse_unique [symmetric], simp add: mult_exp_exp)
paulson@15077
   585
huffman@29170
   586
lemma exp_diff: "exp (x - y) = exp x / exp y"
huffman@29170
   587
  unfolding diff_minus divide_inverse
huffman@29170
   588
  by (simp add: exp_add exp_minus)
paulson@15077
   589
huffman@29167
   590
huffman@29167
   591
subsubsection {* Properties of the Exponential Function on Reals *}
huffman@29167
   592
huffman@29170
   593
text {* Comparisons of @{term "exp x"} with zero. *}
huffman@29167
   594
huffman@29167
   595
text{*Proof: because every exponential can be seen as a square.*}
huffman@29167
   596
lemma exp_ge_zero [simp]: "0 \<le> exp (x::real)"
huffman@29167
   597
proof -
huffman@29167
   598
  have "0 \<le> exp (x/2) * exp (x/2)" by simp
huffman@29167
   599
  thus ?thesis by (simp add: exp_add [symmetric])
huffman@29167
   600
qed
huffman@29167
   601
huffman@23115
   602
lemma exp_gt_zero [simp]: "0 < exp (x::real)"
paulson@15077
   603
by (simp add: order_less_le)
paulson@15077
   604
huffman@29170
   605
lemma not_exp_less_zero [simp]: "\<not> exp (x::real) < 0"
huffman@29170
   606
by (simp add: not_less)
huffman@29170
   607
huffman@29170
   608
lemma not_exp_le_zero [simp]: "\<not> exp (x::real) \<le> 0"
huffman@29170
   609
by (simp add: not_le)
paulson@15077
   610
huffman@23115
   611
lemma abs_exp_cancel [simp]: "\<bar>exp x::real\<bar> = exp x"
huffman@29165
   612
by simp
paulson@15077
   613
paulson@15077
   614
lemma exp_real_of_nat_mult: "exp(real n * x) = exp(x) ^ n"
paulson@15251
   615
apply (induct "n")
paulson@15077
   616
apply (auto simp add: real_of_nat_Suc right_distrib exp_add mult_commute)
paulson@15077
   617
done
paulson@15077
   618
huffman@29170
   619
text {* Strict monotonicity of exponential. *}
huffman@29170
   620
huffman@29170
   621
lemma exp_ge_add_one_self_aux: "0 \<le> (x::real) ==> (1 + x) \<le> exp(x)"
huffman@29170
   622
apply (drule order_le_imp_less_or_eq, auto)
huffman@29170
   623
apply (simp add: exp_def)
huffman@29170
   624
apply (rule real_le_trans)
huffman@29170
   625
apply (rule_tac [2] n = 2 and f = "(%n. inverse (real (fact n)) * x ^ n)" in series_pos_le)
huffman@29170
   626
apply (auto intro: summable_exp simp add: numeral_2_eq_2 zero_le_mult_iff)
huffman@29170
   627
done
huffman@29170
   628
huffman@29170
   629
lemma exp_gt_one: "0 < (x::real) \<Longrightarrow> 1 < exp x"
huffman@29170
   630
proof -
huffman@29170
   631
  assume x: "0 < x"
huffman@29170
   632
  hence "1 < 1 + x" by simp
huffman@29170
   633
  also from x have "1 + x \<le> exp x"
huffman@29170
   634
    by (simp add: exp_ge_add_one_self_aux)
huffman@29170
   635
  finally show ?thesis .
huffman@29170
   636
qed
huffman@29170
   637
paulson@15077
   638
lemma exp_less_mono:
huffman@23115
   639
  fixes x y :: real
huffman@29165
   640
  assumes "x < y" shows "exp x < exp y"
paulson@15077
   641
proof -
huffman@29165
   642
  from `x < y` have "0 < y - x" by simp
huffman@29165
   643
  hence "1 < exp (y - x)" by (rule exp_gt_one)
huffman@29165
   644
  hence "1 < exp y / exp x" by (simp only: exp_diff)
huffman@29165
   645
  thus "exp x < exp y" by simp
paulson@15077
   646
qed
paulson@15077
   647
huffman@23115
   648
lemma exp_less_cancel: "exp (x::real) < exp y ==> x < y"
huffman@29170
   649
apply (simp add: linorder_not_le [symmetric])
huffman@29170
   650
apply (auto simp add: order_le_less exp_less_mono)
paulson@15077
   651
done
paulson@15077
   652
huffman@29170
   653
lemma exp_less_cancel_iff [iff]: "exp (x::real) < exp y \<longleftrightarrow> x < y"
paulson@15077
   654
by (auto intro: exp_less_mono exp_less_cancel)
paulson@15077
   655
huffman@29170
   656
lemma exp_le_cancel_iff [iff]: "exp (x::real) \<le> exp y \<longleftrightarrow> x \<le> y"
paulson@15077
   657
by (auto simp add: linorder_not_less [symmetric])
paulson@15077
   658
huffman@29170
   659
lemma exp_inj_iff [iff]: "exp (x::real) = exp y \<longleftrightarrow> x = y"
paulson@15077
   660
by (simp add: order_eq_iff)
paulson@15077
   661
huffman@29170
   662
text {* Comparisons of @{term "exp x"} with one. *}
huffman@29170
   663
huffman@29170
   664
lemma one_less_exp_iff [simp]: "1 < exp (x::real) \<longleftrightarrow> 0 < x"
huffman@29170
   665
  using exp_less_cancel_iff [where x=0 and y=x] by simp
huffman@29170
   666
huffman@29170
   667
lemma exp_less_one_iff [simp]: "exp (x::real) < 1 \<longleftrightarrow> x < 0"
huffman@29170
   668
  using exp_less_cancel_iff [where x=x and y=0] by simp
huffman@29170
   669
huffman@29170
   670
lemma one_le_exp_iff [simp]: "1 \<le> exp (x::real) \<longleftrightarrow> 0 \<le> x"
huffman@29170
   671
  using exp_le_cancel_iff [where x=0 and y=x] by simp
huffman@29170
   672
huffman@29170
   673
lemma exp_le_one_iff [simp]: "exp (x::real) \<le> 1 \<longleftrightarrow> x \<le> 0"
huffman@29170
   674
  using exp_le_cancel_iff [where x=x and y=0] by simp
huffman@29170
   675
huffman@29170
   676
lemma exp_eq_one_iff [simp]: "exp (x::real) = 1 \<longleftrightarrow> x = 0"
huffman@29170
   677
  using exp_inj_iff [where x=x and y=0] by simp
huffman@29170
   678
huffman@23115
   679
lemma lemma_exp_total: "1 \<le> y ==> \<exists>x. 0 \<le> x & x \<le> y - 1 & exp(x::real) = y"
paulson@15077
   680
apply (rule IVT)
huffman@23045
   681
apply (auto intro: isCont_exp simp add: le_diff_eq)
paulson@15077
   682
apply (subgoal_tac "1 + (y - 1) \<le> exp (y - 1)") 
huffman@29165
   683
apply simp
avigad@17014
   684
apply (rule exp_ge_add_one_self_aux, simp)
paulson@15077
   685
done
paulson@15077
   686
huffman@23115
   687
lemma exp_total: "0 < (y::real) ==> \<exists>x. exp x = y"
paulson@15077
   688
apply (rule_tac x = 1 and y = y in linorder_cases)
paulson@15077
   689
apply (drule order_less_imp_le [THEN lemma_exp_total])
paulson@15077
   690
apply (rule_tac [2] x = 0 in exI)
paulson@15077
   691
apply (frule_tac [3] real_inverse_gt_one)
paulson@15077
   692
apply (drule_tac [4] order_less_imp_le [THEN lemma_exp_total], auto)
paulson@15077
   693
apply (rule_tac x = "-x" in exI)
paulson@15077
   694
apply (simp add: exp_minus)
paulson@15077
   695
done
paulson@15077
   696
paulson@15077
   697
huffman@29164
   698
subsection {* Natural Logarithm *}
paulson@15077
   699
huffman@23043
   700
definition
huffman@23043
   701
  ln :: "real => real" where
huffman@23043
   702
  "ln x = (THE u. exp u = x)"
huffman@23043
   703
huffman@23043
   704
lemma ln_exp [simp]: "ln (exp x) = x"
paulson@15077
   705
by (simp add: ln_def)
paulson@15077
   706
huffman@22654
   707
lemma exp_ln [simp]: "0 < x \<Longrightarrow> exp (ln x) = x"
huffman@22654
   708
by (auto dest: exp_total)
huffman@22654
   709
huffman@29171
   710
lemma exp_ln_iff [simp]: "exp (ln x) = x \<longleftrightarrow> 0 < x"
huffman@29171
   711
apply (rule iffI)
huffman@29171
   712
apply (erule subst, rule exp_gt_zero)
huffman@29171
   713
apply (erule exp_ln)
paulson@15077
   714
done
paulson@15077
   715
huffman@29171
   716
lemma ln_unique: "exp y = x \<Longrightarrow> ln x = y"
huffman@29171
   717
by (erule subst, rule ln_exp)
huffman@29171
   718
huffman@29171
   719
lemma ln_one [simp]: "ln 1 = 0"
huffman@29171
   720
by (rule ln_unique, simp)
huffman@29171
   721
huffman@29171
   722
lemma ln_mult: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln (x * y) = ln x + ln y"
huffman@29171
   723
by (rule ln_unique, simp add: exp_add)
huffman@29171
   724
huffman@29171
   725
lemma ln_inverse: "0 < x \<Longrightarrow> ln (inverse x) = - ln x"
huffman@29171
   726
by (rule ln_unique, simp add: exp_minus)
huffman@29171
   727
huffman@29171
   728
lemma ln_div: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln (x / y) = ln x - ln y"
huffman@29171
   729
by (rule ln_unique, simp add: exp_diff)
paulson@15077
   730
huffman@29171
   731
lemma ln_realpow: "0 < x \<Longrightarrow> ln (x ^ n) = real n * ln x"
huffman@29171
   732
by (rule ln_unique, simp add: exp_real_of_nat_mult)
huffman@29171
   733
huffman@29171
   734
lemma ln_less_cancel_iff [simp]: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln x < ln y \<longleftrightarrow> x < y"
huffman@29171
   735
by (subst exp_less_cancel_iff [symmetric], simp)
huffman@29171
   736
huffman@29171
   737
lemma ln_le_cancel_iff [simp]: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln x \<le> ln y \<longleftrightarrow> x \<le> y"
huffman@29171
   738
by (simp add: linorder_not_less [symmetric])
huffman@29171
   739
huffman@29171
   740
lemma ln_inj_iff [simp]: "\<lbrakk>0 < x; 0 < y\<rbrakk> \<Longrightarrow> ln x = ln y \<longleftrightarrow> x = y"
huffman@29171
   741
by (simp add: order_eq_iff)
huffman@29171
   742
huffman@29171
   743
lemma ln_add_one_self_le_self [simp]: "0 \<le> x \<Longrightarrow> ln (1 + x) \<le> x"
huffman@29171
   744
apply (rule exp_le_cancel_iff [THEN iffD1])
huffman@29171
   745
apply (simp add: exp_ge_add_one_self_aux)
paulson@15077
   746
done
paulson@15077
   747
huffman@29171
   748
lemma ln_less_self [simp]: "0 < x \<Longrightarrow> ln x < x"
huffman@29171
   749
by (rule order_less_le_trans [where y="ln (1 + x)"]) simp_all
paulson@15077
   750
paulson@15234
   751
lemma ln_ge_zero [simp]:
paulson@15077
   752
  assumes x: "1 \<le> x" shows "0 \<le> ln x"
paulson@15077
   753
proof -
paulson@15077
   754
  have "0 < x" using x by arith
paulson@15077
   755
  hence "exp 0 \<le> exp (ln x)"
huffman@22915
   756
    by (simp add: x)
paulson@15077
   757
  thus ?thesis by (simp only: exp_le_cancel_iff)
paulson@15077
   758
qed
paulson@15077
   759
paulson@15077
   760
lemma ln_ge_zero_imp_ge_one:
paulson@15077
   761
  assumes ln: "0 \<le> ln x" 
paulson@15077
   762
      and x:  "0 < x"
paulson@15077
   763
  shows "1 \<le> x"
paulson@15077
   764
proof -
paulson@15077
   765
  from ln have "ln 1 \<le> ln x" by simp
paulson@15077
   766
  thus ?thesis by (simp add: x del: ln_one) 
paulson@15077
   767
qed
paulson@15077
   768
paulson@15077
   769
lemma ln_ge_zero_iff [simp]: "0 < x ==> (0 \<le> ln x) = (1 \<le> x)"
paulson@15077
   770
by (blast intro: ln_ge_zero ln_ge_zero_imp_ge_one)
paulson@15077
   771
paulson@15234
   772
lemma ln_less_zero_iff [simp]: "0 < x ==> (ln x < 0) = (x < 1)"
paulson@15234
   773
by (insert ln_ge_zero_iff [of x], arith)
paulson@15234
   774
paulson@15077
   775
lemma ln_gt_zero:
paulson@15077
   776
  assumes x: "1 < x" shows "0 < ln x"
paulson@15077
   777
proof -
paulson@15077
   778
  have "0 < x" using x by arith
huffman@22915
   779
  hence "exp 0 < exp (ln x)" by (simp add: x)
paulson@15077
   780
  thus ?thesis  by (simp only: exp_less_cancel_iff)
paulson@15077
   781
qed
paulson@15077
   782
paulson@15077
   783
lemma ln_gt_zero_imp_gt_one:
paulson@15077
   784
  assumes ln: "0 < ln x" 
paulson@15077
   785
      and x:  "0 < x"
paulson@15077
   786
  shows "1 < x"
paulson@15077
   787
proof -
paulson@15077
   788
  from ln have "ln 1 < ln x" by simp
paulson@15077
   789
  thus ?thesis by (simp add: x del: ln_one) 
paulson@15077
   790
qed
paulson@15077
   791
paulson@15077
   792
lemma ln_gt_zero_iff [simp]: "0 < x ==> (0 < ln x) = (1 < x)"
paulson@15077
   793
by (blast intro: ln_gt_zero ln_gt_zero_imp_gt_one)
paulson@15077
   794
paulson@15234
   795
lemma ln_eq_zero_iff [simp]: "0 < x ==> (ln x = 0) = (x = 1)"
paulson@15234
   796
by (insert ln_less_zero_iff [of x] ln_gt_zero_iff [of x], arith)
paulson@15077
   797
paulson@15077
   798
lemma ln_less_zero: "[| 0 < x; x < 1 |] ==> ln x < 0"
paulson@15234
   799
by simp
paulson@15077
   800
paulson@15077
   801
lemma exp_ln_eq: "exp u = x ==> ln x = u"
paulson@15077
   802
by auto
paulson@15077
   803
huffman@23045
   804
lemma isCont_ln: "0 < x \<Longrightarrow> isCont ln x"
huffman@23045
   805
apply (subgoal_tac "isCont ln (exp (ln x))", simp)
huffman@23045
   806
apply (rule isCont_inverse_function [where f=exp], simp_all)
huffman@23045
   807
done
huffman@23045
   808
huffman@23045
   809
lemma DERIV_ln: "0 < x \<Longrightarrow> DERIV ln x :> inverse x"
huffman@23045
   810
apply (rule DERIV_inverse_function [where f=exp and a=0 and b="x+1"])
huffman@23045
   811
apply (erule lemma_DERIV_subst [OF DERIV_exp exp_ln])
huffman@23045
   812
apply (simp_all add: abs_if isCont_ln)
huffman@23045
   813
done
huffman@23045
   814
paulson@15077
   815
huffman@29164
   816
subsection {* Sine and Cosine *}
huffman@29164
   817
huffman@29164
   818
definition
huffman@29164
   819
  sin :: "real => real" where
huffman@29164
   820
  "sin x = (\<Sum>n. (if even(n) then 0 else
huffman@29164
   821
             (-1 ^ ((n - Suc 0) div 2))/(real (fact n))) * x ^ n)"
huffman@29164
   822
 
huffman@29164
   823
definition
huffman@29164
   824
  cos :: "real => real" where
huffman@29164
   825
  "cos x = (\<Sum>n. (if even(n) then (-1 ^ (n div 2))/(real (fact n)) 
huffman@29164
   826
                            else 0) * x ^ n)"
huffman@29164
   827
huffman@29164
   828
lemma summable_sin: 
huffman@29164
   829
     "summable (%n.  
huffman@29164
   830
           (if even n then 0  
huffman@29164
   831
           else -1 ^ ((n - Suc 0) div 2)/(real (fact n))) *  
huffman@29164
   832
                x ^ n)"
huffman@29164
   833
apply (rule_tac g = "(%n. inverse (real (fact n)) * \<bar>x\<bar> ^ n)" in summable_comparison_test)
huffman@29164
   834
apply (rule_tac [2] summable_exp)
huffman@29164
   835
apply (rule_tac x = 0 in exI)
huffman@29164
   836
apply (auto simp add: divide_inverse abs_mult power_abs [symmetric] zero_le_mult_iff)
huffman@29164
   837
done
huffman@29164
   838
huffman@29164
   839
lemma summable_cos: 
huffman@29164
   840
      "summable (%n.  
huffman@29164
   841
           (if even n then  
huffman@29164
   842
           -1 ^ (n div 2)/(real (fact n)) else 0) * x ^ n)"
huffman@29164
   843
apply (rule_tac g = "(%n. inverse (real (fact n)) * \<bar>x\<bar> ^ n)" in summable_comparison_test)
huffman@29164
   844
apply (rule_tac [2] summable_exp)
huffman@29164
   845
apply (rule_tac x = 0 in exI)
huffman@29164
   846
apply (auto simp add: divide_inverse abs_mult power_abs [symmetric] zero_le_mult_iff)
huffman@29164
   847
done
huffman@29164
   848
huffman@29164
   849
lemma lemma_STAR_sin:
huffman@29164
   850
     "(if even n then 0  
huffman@29164
   851
       else -1 ^ ((n - Suc 0) div 2)/(real (fact n))) * 0 ^ n = 0"
huffman@29164
   852
by (induct "n", auto)
huffman@29164
   853
huffman@29164
   854
lemma lemma_STAR_cos:
huffman@29164
   855
     "0 < n -->  
huffman@29164
   856
      -1 ^ (n div 2)/(real (fact n)) * 0 ^ n = 0"
huffman@29164
   857
by (induct "n", auto)
huffman@29164
   858
huffman@29164
   859
lemma lemma_STAR_cos1:
huffman@29164
   860
     "0 < n -->  
huffman@29164
   861
      (-1) ^ (n div 2)/(real (fact n)) * 0 ^ n = 0"
huffman@29164
   862
by (induct "n", auto)
huffman@29164
   863
huffman@29164
   864
lemma lemma_STAR_cos2:
huffman@29164
   865
  "(\<Sum>n=1..<n. if even n then -1 ^ (n div 2)/(real (fact n)) *  0 ^ n 
huffman@29164
   866
                         else 0) = 0"
huffman@29164
   867
apply (induct "n")
huffman@29164
   868
apply (case_tac [2] "n", auto)
huffman@29164
   869
done
huffman@29164
   870
huffman@29164
   871
lemma sin_converges: 
huffman@29164
   872
      "(%n. (if even n then 0  
huffman@29164
   873
            else -1 ^ ((n - Suc 0) div 2)/(real (fact n))) *  
huffman@29164
   874
                 x ^ n) sums sin(x)"
huffman@29164
   875
unfolding sin_def by (rule summable_sin [THEN summable_sums])
huffman@29164
   876
huffman@29164
   877
lemma cos_converges: 
huffman@29164
   878
      "(%n. (if even n then  
huffman@29164
   879
           -1 ^ (n div 2)/(real (fact n))  
huffman@29164
   880
           else 0) * x ^ n) sums cos(x)"
huffman@29164
   881
unfolding cos_def by (rule summable_cos [THEN summable_sums])
huffman@29164
   882
huffman@29164
   883
lemma sin_fdiffs: 
huffman@29164
   884
      "diffs(%n. if even n then 0  
huffman@29164
   885
           else -1 ^ ((n - Suc 0) div 2)/(real (fact n)))  
huffman@29164
   886
       = (%n. if even n then  
huffman@29164
   887
                 -1 ^ (n div 2)/(real (fact n))  
huffman@29164
   888
              else 0)"
huffman@29164
   889
by (auto intro!: ext 
huffman@29164
   890
         simp add: diffs_def divide_inverse real_of_nat_def of_nat_mult
huffman@29164
   891
         simp del: mult_Suc of_nat_Suc)
huffman@29164
   892
huffman@29164
   893
lemma sin_fdiffs2: 
huffman@29164
   894
       "diffs(%n. if even n then 0  
huffman@29164
   895
           else -1 ^ ((n - Suc 0) div 2)/(real (fact n))) n  
huffman@29164
   896
       = (if even n then  
huffman@29164
   897
                 -1 ^ (n div 2)/(real (fact n))  
huffman@29164
   898
              else 0)"
huffman@29164
   899
by (simp only: sin_fdiffs)
huffman@29164
   900
huffman@29164
   901
lemma cos_fdiffs: 
huffman@29164
   902
      "diffs(%n. if even n then  
huffman@29164
   903
                 -1 ^ (n div 2)/(real (fact n)) else 0)  
huffman@29164
   904
       = (%n. - (if even n then 0  
huffman@29164
   905
           else -1 ^ ((n - Suc 0)div 2)/(real (fact n))))"
huffman@29164
   906
by (auto intro!: ext 
huffman@29164
   907
         simp add: diffs_def divide_inverse odd_Suc_mult_two_ex real_of_nat_def of_nat_mult
huffman@29164
   908
         simp del: mult_Suc of_nat_Suc)
huffman@29164
   909
huffman@29164
   910
huffman@29164
   911
lemma cos_fdiffs2: 
huffman@29164
   912
      "diffs(%n. if even n then  
huffman@29164
   913
                 -1 ^ (n div 2)/(real (fact n)) else 0) n 
huffman@29164
   914
       = - (if even n then 0  
huffman@29164
   915
           else -1 ^ ((n - Suc 0)div 2)/(real (fact n)))"
huffman@29164
   916
by (simp only: cos_fdiffs)
huffman@29164
   917
huffman@29164
   918
text{*Now at last we can get the derivatives of exp, sin and cos*}
huffman@29164
   919
huffman@29164
   920
lemma lemma_sin_minus:
huffman@29164
   921
     "- sin x = (\<Sum>n. - ((if even n then 0 
huffman@29164
   922
                  else -1 ^ ((n - Suc 0) div 2)/(real (fact n))) * x ^ n))"
huffman@29164
   923
by (auto intro!: sums_unique sums_minus sin_converges)
huffman@29164
   924
huffman@29164
   925
lemma lemma_sin_ext:
huffman@29164
   926
     "sin = (%x. \<Sum>n. 
huffman@29164
   927
                   (if even n then 0  
huffman@29164
   928
                       else -1 ^ ((n - Suc 0) div 2)/(real (fact n))) *  
huffman@29164
   929
                   x ^ n)"
huffman@29164
   930
by (auto intro!: ext simp add: sin_def)
huffman@29164
   931
huffman@29164
   932
lemma lemma_cos_ext:
huffman@29164
   933
     "cos = (%x. \<Sum>n. 
huffman@29164
   934
                   (if even n then -1 ^ (n div 2)/(real (fact n)) else 0) *
huffman@29164
   935
                   x ^ n)"
huffman@29164
   936
by (auto intro!: ext simp add: cos_def)
huffman@29164
   937
huffman@29164
   938
lemma DERIV_sin [simp]: "DERIV sin x :> cos(x)"
huffman@29164
   939
apply (simp add: cos_def)
huffman@29164
   940
apply (subst lemma_sin_ext)
huffman@29164
   941
apply (auto simp add: sin_fdiffs2 [symmetric])
huffman@29164
   942
apply (rule_tac K = "1 + \<bar>x\<bar>" in termdiffs)
huffman@29164
   943
apply (auto intro: sin_converges cos_converges sums_summable intro!: sums_minus [THEN sums_summable] simp add: cos_fdiffs sin_fdiffs)
huffman@29164
   944
done
huffman@29164
   945
huffman@29164
   946
lemma DERIV_cos [simp]: "DERIV cos x :> -sin(x)"
huffman@29164
   947
apply (subst lemma_cos_ext)
huffman@29164
   948
apply (auto simp add: lemma_sin_minus cos_fdiffs2 [symmetric] minus_mult_left)
huffman@29164
   949
apply (rule_tac K = "1 + \<bar>x\<bar>" in termdiffs)
huffman@29164
   950
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
   951
done
huffman@29164
   952
huffman@29164
   953
lemma isCont_sin [simp]: "isCont sin x"
huffman@29164
   954
by (rule DERIV_sin [THEN DERIV_isCont])
huffman@29164
   955
huffman@29164
   956
lemma isCont_cos [simp]: "isCont cos x"
huffman@29164
   957
by (rule DERIV_cos [THEN DERIV_isCont])
huffman@29164
   958
huffman@29164
   959
huffman@29164
   960
subsection {* Properties of Sine and Cosine *}
paulson@15077
   961
paulson@15077
   962
lemma sin_zero [simp]: "sin 0 = 0"
huffman@23278
   963
unfolding sin_def by (simp add: powser_zero)
paulson@15077
   964
paulson@15077
   965
lemma cos_zero [simp]: "cos 0 = 1"
huffman@23278
   966
unfolding cos_def by (simp add: powser_zero)
paulson@15077
   967
paulson@15077
   968
lemma DERIV_sin_sin_mult [simp]:
paulson@15077
   969
     "DERIV (%x. sin(x)*sin(x)) x :> cos(x) * sin(x) + cos(x) * sin(x)"
paulson@15077
   970
by (rule DERIV_mult, auto)
paulson@15077
   971
paulson@15077
   972
lemma DERIV_sin_sin_mult2 [simp]:
paulson@15077
   973
     "DERIV (%x. sin(x)*sin(x)) x :> 2 * cos(x) * sin(x)"
paulson@15077
   974
apply (cut_tac x = x in DERIV_sin_sin_mult)
paulson@15077
   975
apply (auto simp add: mult_assoc)
paulson@15077
   976
done
paulson@15077
   977
paulson@15077
   978
lemma DERIV_sin_realpow2 [simp]:
paulson@15077
   979
     "DERIV (%x. (sin x)\<twosuperior>) x :> cos(x) * sin(x) + cos(x) * sin(x)"
paulson@15077
   980
by (auto simp add: numeral_2_eq_2 real_mult_assoc [symmetric])
paulson@15077
   981
paulson@15077
   982
lemma DERIV_sin_realpow2a [simp]:
paulson@15077
   983
     "DERIV (%x. (sin x)\<twosuperior>) x :> 2 * cos(x) * sin(x)"
paulson@15077
   984
by (auto simp add: numeral_2_eq_2)
paulson@15077
   985
paulson@15077
   986
lemma DERIV_cos_cos_mult [simp]:
paulson@15077
   987
     "DERIV (%x. cos(x)*cos(x)) x :> -sin(x) * cos(x) + -sin(x) * cos(x)"
paulson@15077
   988
by (rule DERIV_mult, auto)
paulson@15077
   989
paulson@15077
   990
lemma DERIV_cos_cos_mult2 [simp]:
paulson@15077
   991
     "DERIV (%x. cos(x)*cos(x)) x :> -2 * cos(x) * sin(x)"
paulson@15077
   992
apply (cut_tac x = x in DERIV_cos_cos_mult)
paulson@15077
   993
apply (auto simp add: mult_ac)
paulson@15077
   994
done
paulson@15077
   995
paulson@15077
   996
lemma DERIV_cos_realpow2 [simp]:
paulson@15077
   997
     "DERIV (%x. (cos x)\<twosuperior>) x :> -sin(x) * cos(x) + -sin(x) * cos(x)"
paulson@15077
   998
by (auto simp add: numeral_2_eq_2 real_mult_assoc [symmetric])
paulson@15077
   999
paulson@15077
  1000
lemma DERIV_cos_realpow2a [simp]:
paulson@15077
  1001
     "DERIV (%x. (cos x)\<twosuperior>) x :> -2 * cos(x) * sin(x)"
paulson@15077
  1002
by (auto simp add: numeral_2_eq_2)
paulson@15077
  1003
paulson@15077
  1004
lemma lemma_DERIV_subst: "[| DERIV f x :> D; D = E |] ==> DERIV f x :> E"
paulson@15077
  1005
by auto
paulson@15077
  1006
paulson@15077
  1007
lemma DERIV_cos_realpow2b: "DERIV (%x. (cos x)\<twosuperior>) x :> -(2 * cos(x) * sin(x))"
paulson@15077
  1008
apply (rule lemma_DERIV_subst)
paulson@15077
  1009
apply (rule DERIV_cos_realpow2a, auto)
paulson@15077
  1010
done
paulson@15077
  1011
paulson@15077
  1012
(* most useful *)
paulson@15229
  1013
lemma DERIV_cos_cos_mult3 [simp]:
paulson@15229
  1014
     "DERIV (%x. cos(x)*cos(x)) x :> -(2 * cos(x) * sin(x))"
paulson@15077
  1015
apply (rule lemma_DERIV_subst)
paulson@15077
  1016
apply (rule DERIV_cos_cos_mult2, auto)
paulson@15077
  1017
done
paulson@15077
  1018
paulson@15077
  1019
lemma DERIV_sin_circle_all: 
paulson@15077
  1020
     "\<forall>x. DERIV (%x. (sin x)\<twosuperior> + (cos x)\<twosuperior>) x :>  
paulson@15077
  1021
             (2*cos(x)*sin(x) - 2*cos(x)*sin(x))"
paulson@15229
  1022
apply (simp only: diff_minus, safe)
paulson@15229
  1023
apply (rule DERIV_add) 
paulson@15077
  1024
apply (auto simp add: numeral_2_eq_2)
paulson@15077
  1025
done
paulson@15077
  1026
paulson@15229
  1027
lemma DERIV_sin_circle_all_zero [simp]:
paulson@15229
  1028
     "\<forall>x. DERIV (%x. (sin x)\<twosuperior> + (cos x)\<twosuperior>) x :> 0"
paulson@15077
  1029
by (cut_tac DERIV_sin_circle_all, auto)
paulson@15077
  1030
paulson@15077
  1031
lemma sin_cos_squared_add [simp]: "((sin x)\<twosuperior>) + ((cos x)\<twosuperior>) = 1"
paulson@15077
  1032
apply (cut_tac x = x and y = 0 in DERIV_sin_circle_all_zero [THEN DERIV_isconst_all])
paulson@15077
  1033
apply (auto simp add: numeral_2_eq_2)
paulson@15077
  1034
done
paulson@15077
  1035
paulson@15077
  1036
lemma sin_cos_squared_add2 [simp]: "((cos x)\<twosuperior>) + ((sin x)\<twosuperior>) = 1"
huffman@23286
  1037
apply (subst add_commute)
paulson@15077
  1038
apply (simp (no_asm) del: realpow_Suc)
paulson@15077
  1039
done
paulson@15077
  1040
paulson@15077
  1041
lemma sin_cos_squared_add3 [simp]: "cos x * cos x + sin x * sin x = 1"
paulson@15077
  1042
apply (cut_tac x = x in sin_cos_squared_add2)
paulson@15077
  1043
apply (auto simp add: numeral_2_eq_2)
paulson@15077
  1044
done
paulson@15077
  1045
paulson@15077
  1046
lemma sin_squared_eq: "(sin x)\<twosuperior> = 1 - (cos x)\<twosuperior>"
paulson@15229
  1047
apply (rule_tac a1 = "(cos x)\<twosuperior>" in add_right_cancel [THEN iffD1])
paulson@15077
  1048
apply (simp del: realpow_Suc)
paulson@15077
  1049
done
paulson@15077
  1050
paulson@15077
  1051
lemma cos_squared_eq: "(cos x)\<twosuperior> = 1 - (sin x)\<twosuperior>"
paulson@15077
  1052
apply (rule_tac a1 = "(sin x)\<twosuperior>" in add_right_cancel [THEN iffD1])
paulson@15077
  1053
apply (simp del: realpow_Suc)
paulson@15077
  1054
done
paulson@15077
  1055
paulson@15081
  1056
lemma abs_sin_le_one [simp]: "\<bar>sin x\<bar> \<le> 1"
huffman@23097
  1057
by (rule power2_le_imp_le, simp_all add: sin_squared_eq)
paulson@15077
  1058
paulson@15077
  1059
lemma sin_ge_minus_one [simp]: "-1 \<le> sin x"
paulson@15077
  1060
apply (insert abs_sin_le_one [of x]) 
huffman@22998
  1061
apply (simp add: abs_le_iff del: abs_sin_le_one) 
paulson@15077
  1062
done
paulson@15077
  1063
paulson@15077
  1064
lemma sin_le_one [simp]: "sin x \<le> 1"
paulson@15077
  1065
apply (insert abs_sin_le_one [of x]) 
huffman@22998
  1066
apply (simp add: abs_le_iff del: abs_sin_le_one) 
paulson@15077
  1067
done
paulson@15077
  1068
paulson@15081
  1069
lemma abs_cos_le_one [simp]: "\<bar>cos x\<bar> \<le> 1"
huffman@23097
  1070
by (rule power2_le_imp_le, simp_all add: cos_squared_eq)
paulson@15077
  1071
paulson@15077
  1072
lemma cos_ge_minus_one [simp]: "-1 \<le> cos x"
paulson@15077
  1073
apply (insert abs_cos_le_one [of x]) 
huffman@22998
  1074
apply (simp add: abs_le_iff del: abs_cos_le_one) 
paulson@15077
  1075
done
paulson@15077
  1076
paulson@15077
  1077
lemma cos_le_one [simp]: "cos x \<le> 1"
paulson@15077
  1078
apply (insert abs_cos_le_one [of x]) 
huffman@22998
  1079
apply (simp add: abs_le_iff del: abs_cos_le_one)
paulson@15077
  1080
done
paulson@15077
  1081
paulson@15077
  1082
lemma DERIV_fun_pow: "DERIV g x :> m ==>  
paulson@15077
  1083
      DERIV (%x. (g x) ^ n) x :> real n * (g x) ^ (n - 1) * m"
paulson@15077
  1084
apply (rule lemma_DERIV_subst)
paulson@15229
  1085
apply (rule_tac f = "(%x. x ^ n)" in DERIV_chain2)
paulson@15077
  1086
apply (rule DERIV_pow, auto)
paulson@15077
  1087
done
paulson@15077
  1088
paulson@15229
  1089
lemma DERIV_fun_exp:
paulson@15229
  1090
     "DERIV g x :> m ==> DERIV (%x. exp(g x)) x :> exp(g x) * m"
paulson@15077
  1091
apply (rule lemma_DERIV_subst)
paulson@15077
  1092
apply (rule_tac f = exp in DERIV_chain2)
paulson@15077
  1093
apply (rule DERIV_exp, auto)
paulson@15077
  1094
done
paulson@15077
  1095
paulson@15229
  1096
lemma DERIV_fun_sin:
paulson@15229
  1097
     "DERIV g x :> m ==> DERIV (%x. sin(g x)) x :> cos(g x) * m"
paulson@15077
  1098
apply (rule lemma_DERIV_subst)
paulson@15077
  1099
apply (rule_tac f = sin in DERIV_chain2)
paulson@15077
  1100
apply (rule DERIV_sin, auto)
paulson@15077
  1101
done
paulson@15077
  1102
paulson@15229
  1103
lemma DERIV_fun_cos:
paulson@15229
  1104
     "DERIV g x :> m ==> DERIV (%x. cos(g x)) x :> -sin(g x) * m"
paulson@15077
  1105
apply (rule lemma_DERIV_subst)
paulson@15077
  1106
apply (rule_tac f = cos in DERIV_chain2)
paulson@15077
  1107
apply (rule DERIV_cos, auto)
paulson@15077
  1108
done
paulson@15077
  1109
huffman@23069
  1110
lemmas DERIV_intros = DERIV_ident DERIV_const DERIV_cos DERIV_cmult 
paulson@15077
  1111
                    DERIV_sin  DERIV_exp  DERIV_inverse DERIV_pow 
paulson@15077
  1112
                    DERIV_add  DERIV_diff  DERIV_mult  DERIV_minus 
paulson@15077
  1113
                    DERIV_inverse_fun DERIV_quotient DERIV_fun_pow 
paulson@15077
  1114
                    DERIV_fun_exp DERIV_fun_sin DERIV_fun_cos 
paulson@15077
  1115
paulson@15077
  1116
(* lemma *)
paulson@15229
  1117
lemma lemma_DERIV_sin_cos_add:
paulson@15229
  1118
     "\<forall>x.  
paulson@15077
  1119
         DERIV (%x. (sin (x + y) - (sin x * cos y + cos x * sin y)) ^ 2 +  
paulson@15077
  1120
               (cos (x + y) - (cos x * cos y - sin x * sin y)) ^ 2) x :> 0"
paulson@15077
  1121
apply (safe, rule lemma_DERIV_subst)
paulson@15077
  1122
apply (best intro!: DERIV_intros intro: DERIV_chain2) 
paulson@15077
  1123
  --{*replaces the old @{text DERIV_tac}*}
nipkow@29667
  1124
apply (auto simp add: algebra_simps)
paulson@15077
  1125
done
paulson@15077
  1126
paulson@15077
  1127
lemma sin_cos_add [simp]:
paulson@15077
  1128
     "(sin (x + y) - (sin x * cos y + cos x * sin y)) ^ 2 +  
paulson@15077
  1129
      (cos (x + y) - (cos x * cos y - sin x * sin y)) ^ 2 = 0"
paulson@15077
  1130
apply (cut_tac y = 0 and x = x and y7 = y 
paulson@15077
  1131
       in lemma_DERIV_sin_cos_add [THEN DERIV_isconst_all])
paulson@15077
  1132
apply (auto simp add: numeral_2_eq_2)
paulson@15077
  1133
done
paulson@15077
  1134
paulson@15077
  1135
lemma sin_add: "sin (x + y) = sin x * cos y + cos x * sin y"
paulson@15077
  1136
apply (cut_tac x = x and y = y in sin_cos_add)
huffman@22969
  1137
apply (simp del: sin_cos_add)
paulson@15077
  1138
done
paulson@15077
  1139
paulson@15077
  1140
lemma cos_add: "cos (x + y) = cos x * cos y - sin x * sin y"
paulson@15077
  1141
apply (cut_tac x = x and y = y in sin_cos_add)
huffman@22969
  1142
apply (simp del: sin_cos_add)
paulson@15077
  1143
done
paulson@15077
  1144
paulson@15085
  1145
lemma lemma_DERIV_sin_cos_minus:
paulson@15085
  1146
    "\<forall>x. DERIV (%x. (sin(-x) + (sin x)) ^ 2 + (cos(-x) - (cos x)) ^ 2) x :> 0"
paulson@15077
  1147
apply (safe, rule lemma_DERIV_subst)
nipkow@29667
  1148
apply (best intro!: DERIV_intros intro: DERIV_chain2)
nipkow@29667
  1149
apply (simp add: algebra_simps)
paulson@15077
  1150
done
paulson@15077
  1151
huffman@29165
  1152
lemma sin_cos_minus: 
paulson@15085
  1153
    "(sin(-x) + (sin x)) ^ 2 + (cos(-x) - (cos x)) ^ 2 = 0"
paulson@15085
  1154
apply (cut_tac y = 0 and x = x 
paulson@15085
  1155
       in lemma_DERIV_sin_cos_minus [THEN DERIV_isconst_all])
huffman@22969
  1156
apply simp
paulson@15077
  1157
done
paulson@15077
  1158
paulson@15077
  1159
lemma sin_minus [simp]: "sin (-x) = -sin(x)"
huffman@29165
  1160
  using sin_cos_minus [where x=x] by simp
paulson@15077
  1161
paulson@15077
  1162
lemma cos_minus [simp]: "cos (-x) = cos(x)"
huffman@29165
  1163
  using sin_cos_minus [where x=x] by simp
paulson@15077
  1164
paulson@15077
  1165
lemma sin_diff: "sin (x - y) = sin x * cos y - cos x * sin y"
huffman@22969
  1166
by (simp add: diff_minus sin_add)
paulson@15077
  1167
paulson@15077
  1168
lemma sin_diff2: "sin (x - y) = cos y * sin x - sin y * cos x"
paulson@15077
  1169
by (simp add: sin_diff mult_commute)
paulson@15077
  1170
paulson@15077
  1171
lemma cos_diff: "cos (x - y) = cos x * cos y + sin x * sin y"
huffman@22969
  1172
by (simp add: diff_minus cos_add)
paulson@15077
  1173
paulson@15077
  1174
lemma cos_diff2: "cos (x - y) = cos y * cos x + sin y * sin x"
paulson@15077
  1175
by (simp add: cos_diff mult_commute)
paulson@15077
  1176
paulson@15077
  1177
lemma sin_double [simp]: "sin(2 * x) = 2* sin x * cos x"
huffman@29165
  1178
  using sin_add [where x=x and y=x] by simp
paulson@15077
  1179
paulson@15077
  1180
lemma cos_double: "cos(2* x) = ((cos x)\<twosuperior>) - ((sin x)\<twosuperior>)"
huffman@29165
  1181
  using cos_add [where x=x and y=x]
huffman@29165
  1182
  by (simp add: power2_eq_square)
paulson@15077
  1183
paulson@15077
  1184
huffman@29164
  1185
subsection {* The Constant Pi *}
paulson@15077
  1186
huffman@23043
  1187
definition
huffman@23043
  1188
  pi :: "real" where
huffman@23053
  1189
  "pi = 2 * (THE x. 0 \<le> (x::real) & x \<le> 2 & cos x = 0)"
huffman@23043
  1190
paulson@15077
  1191
text{*Show that there's a least positive @{term x} with @{term "cos(x) = 0"}; 
paulson@15077
  1192
   hence define pi.*}
paulson@15077
  1193
paulson@15077
  1194
lemma sin_paired:
huffman@23177
  1195
     "(%n. -1 ^ n /(real (fact (2 * n + 1))) * x ^ (2 * n + 1)) 
paulson@15077
  1196
      sums  sin x"
paulson@15077
  1197
proof -
paulson@15077
  1198
  have "(\<lambda>n. \<Sum>k = n * 2..<n * 2 + 2.
paulson@15077
  1199
            (if even k then 0
huffman@23177
  1200
             else -1 ^ ((k - Suc 0) div 2) / real (fact k)) *
paulson@15077
  1201
            x ^ k) 
huffman@23176
  1202
	sums sin x"
huffman@23176
  1203
    unfolding sin_def
paulson@15077
  1204
    by (rule sin_converges [THEN sums_summable, THEN sums_group], simp) 
huffman@23176
  1205
  thus ?thesis by (simp add: mult_ac)
paulson@15077
  1206
qed
paulson@15077
  1207
paulson@15077
  1208
lemma sin_gt_zero: "[|0 < x; x < 2 |] ==> 0 < sin x"
paulson@15077
  1209
apply (subgoal_tac 
paulson@15077
  1210
       "(\<lambda>n. \<Sum>k = n * 2..<n * 2 + 2.
huffman@23177
  1211
              -1 ^ k / real (fact (2 * k + 1)) * x ^ (2 * k + 1)) 
huffman@23177
  1212
     sums (\<Sum>n. -1 ^ n / real (fact (2 * n + 1)) * x ^ (2 * n + 1))")
paulson@15077
  1213
 prefer 2
paulson@15077
  1214
 apply (rule sin_paired [THEN sums_summable, THEN sums_group], simp) 
paulson@15077
  1215
apply (rotate_tac 2)
paulson@15077
  1216
apply (drule sin_paired [THEN sums_unique, THEN ssubst])
paulson@15077
  1217
apply (auto simp del: fact_Suc realpow_Suc)
paulson@15077
  1218
apply (frule sums_unique)
paulson@15077
  1219
apply (auto simp del: fact_Suc realpow_Suc)
paulson@15077
  1220
apply (rule_tac n1 = 0 in series_pos_less [THEN [2] order_le_less_trans])
paulson@15077
  1221
apply (auto simp del: fact_Suc realpow_Suc)
paulson@15077
  1222
apply (erule sums_summable)
paulson@15077
  1223
apply (case_tac "m=0")
paulson@15077
  1224
apply (simp (no_asm_simp))
paulson@15234
  1225
apply (subgoal_tac "6 * (x * (x * x) / real (Suc (Suc (Suc (Suc (Suc (Suc 0))))))) < 6 * x") 
nipkow@15539
  1226
apply (simp only: mult_less_cancel_left, simp)  
nipkow@15539
  1227
apply (simp (no_asm_simp) add: numeral_2_eq_2 [symmetric] mult_assoc [symmetric])
paulson@15077
  1228
apply (subgoal_tac "x*x < 2*3", simp) 
paulson@15077
  1229
apply (rule mult_strict_mono)
paulson@15085
  1230
apply (auto simp add: real_0_less_add_iff real_of_nat_Suc simp del: fact_Suc)
paulson@15077
  1231
apply (subst fact_Suc)
paulson@15077
  1232
apply (subst fact_Suc)
paulson@15077
  1233
apply (subst fact_Suc)
paulson@15077
  1234
apply (subst fact_Suc)
paulson@15077
  1235
apply (subst real_of_nat_mult)
paulson@15077
  1236
apply (subst real_of_nat_mult)
paulson@15077
  1237
apply (subst real_of_nat_mult)
paulson@15077
  1238
apply (subst real_of_nat_mult)
nipkow@15539
  1239
apply (simp (no_asm) add: divide_inverse del: fact_Suc)
paulson@15077
  1240
apply (auto simp add: mult_assoc [symmetric] simp del: fact_Suc)
paulson@15077
  1241
apply (rule_tac c="real (Suc (Suc (4*m)))" in mult_less_imp_less_right) 
paulson@15077
  1242
apply (auto simp add: mult_assoc simp del: fact_Suc)
paulson@15077
  1243
apply (rule_tac c="real (Suc (Suc (Suc (4*m))))" in mult_less_imp_less_right) 
paulson@15077
  1244
apply (auto simp add: mult_assoc mult_less_cancel_left simp del: fact_Suc)
paulson@15077
  1245
apply (subgoal_tac "x * (x * x ^ (4*m)) = (x ^ (4*m)) * (x * x)") 
paulson@15077
  1246
apply (erule ssubst)+
paulson@15077
  1247
apply (auto simp del: fact_Suc)
paulson@15077
  1248
apply (subgoal_tac "0 < x ^ (4 * m) ")
paulson@15077
  1249
 prefer 2 apply (simp only: zero_less_power) 
paulson@15077
  1250
apply (simp (no_asm_simp) add: mult_less_cancel_left)
paulson@15077
  1251
apply (rule mult_strict_mono)
paulson@15077
  1252
apply (simp_all (no_asm_simp))
paulson@15077
  1253
done
paulson@15077
  1254
paulson@15077
  1255
lemma sin_gt_zero1: "[|0 < x; x < 2 |] ==> 0 < sin x"
paulson@15077
  1256
by (auto intro: sin_gt_zero)
paulson@15077
  1257
paulson@15077
  1258
lemma cos_double_less_one: "[| 0 < x; x < 2 |] ==> cos (2 * x) < 1"
paulson@15077
  1259
apply (cut_tac x = x in sin_gt_zero1)
paulson@15077
  1260
apply (auto simp add: cos_squared_eq cos_double)
paulson@15077
  1261
done
paulson@15077
  1262
paulson@15077
  1263
lemma cos_paired:
huffman@23177
  1264
     "(%n. -1 ^ n /(real (fact (2 * n))) * x ^ (2 * n)) sums cos x"
paulson@15077
  1265
proof -
paulson@15077
  1266
  have "(\<lambda>n. \<Sum>k = n * 2..<n * 2 + 2.
huffman@23177
  1267
            (if even k then -1 ^ (k div 2) / real (fact k) else 0) *
paulson@15077
  1268
            x ^ k) 
huffman@23176
  1269
        sums cos x"
huffman@23176
  1270
    unfolding cos_def
paulson@15077
  1271
    by (rule cos_converges [THEN sums_summable, THEN sums_group], simp) 
huffman@23176
  1272
  thus ?thesis by (simp add: mult_ac)
paulson@15077
  1273
qed
paulson@15077
  1274
paulson@15077
  1275
lemma fact_lemma: "real (n::nat) * 4 = real (4 * n)"
paulson@15077
  1276
by simp
paulson@15077
  1277
huffman@23053
  1278
lemma cos_two_less_zero [simp]: "cos (2) < 0"
paulson@15077
  1279
apply (cut_tac x = 2 in cos_paired)
paulson@15077
  1280
apply (drule sums_minus)
paulson@15077
  1281
apply (rule neg_less_iff_less [THEN iffD1]) 
nipkow@15539
  1282
apply (frule sums_unique, auto)
nipkow@15539
  1283
apply (rule_tac y =
huffman@23177
  1284
 "\<Sum>n=0..< Suc(Suc(Suc 0)). - (-1 ^ n / (real(fact (2*n))) * 2 ^ (2*n))"
paulson@15481
  1285
       in order_less_trans)
paulson@15077
  1286
apply (simp (no_asm) add: fact_num_eq_if realpow_num_eq_if del: fact_Suc realpow_Suc)
nipkow@15561
  1287
apply (simp (no_asm) add: mult_assoc del: setsum_op_ivl_Suc)
paulson@15077
  1288
apply (rule sumr_pos_lt_pair)
paulson@15077
  1289
apply (erule sums_summable, safe)
paulson@15085
  1290
apply (simp (no_asm) add: divide_inverse real_0_less_add_iff mult_assoc [symmetric] 
paulson@15085
  1291
            del: fact_Suc)
paulson@15077
  1292
apply (rule real_mult_inverse_cancel2)
paulson@15077
  1293
apply (rule real_of_nat_fact_gt_zero)+
paulson@15077
  1294
apply (simp (no_asm) add: mult_assoc [symmetric] del: fact_Suc)
paulson@15077
  1295
apply (subst fact_lemma) 
paulson@15481
  1296
apply (subst fact_Suc [of "Suc (Suc (Suc (Suc (Suc (Suc (Suc (4 * d)))))))"])
paulson@15481
  1297
apply (simp only: real_of_nat_mult)
huffman@23007
  1298
apply (rule mult_strict_mono, force)
huffman@27483
  1299
  apply (rule_tac [3] real_of_nat_ge_zero)
paulson@15481
  1300
 prefer 2 apply force
paulson@15077
  1301
apply (rule real_of_nat_less_iff [THEN iffD2])
paulson@15077
  1302
apply (rule fact_less_mono, auto)
paulson@15077
  1303
done
huffman@23053
  1304
huffman@23053
  1305
lemmas cos_two_neq_zero [simp] = cos_two_less_zero [THEN less_imp_neq]
huffman@23053
  1306
lemmas cos_two_le_zero [simp] = cos_two_less_zero [THEN order_less_imp_le]
paulson@15077
  1307
paulson@15077
  1308
lemma cos_is_zero: "EX! x. 0 \<le> x & x \<le> 2 & cos x = 0"
paulson@15077
  1309
apply (subgoal_tac "\<exists>x. 0 \<le> x & x \<le> 2 & cos x = 0")
paulson@15077
  1310
apply (rule_tac [2] IVT2)
paulson@15077
  1311
apply (auto intro: DERIV_isCont DERIV_cos)
paulson@15077
  1312
apply (cut_tac x = xa and y = y in linorder_less_linear)
paulson@15077
  1313
apply (rule ccontr)
paulson@15077
  1314
apply (subgoal_tac " (\<forall>x. cos differentiable x) & (\<forall>x. isCont cos x) ")
paulson@15077
  1315
apply (auto intro: DERIV_cos DERIV_isCont simp add: differentiable_def)
paulson@15077
  1316
apply (drule_tac f = cos in Rolle)
paulson@15077
  1317
apply (drule_tac [5] f = cos in Rolle)
paulson@15077
  1318
apply (auto dest!: DERIV_cos [THEN DERIV_unique] simp add: differentiable_def)
paulson@15077
  1319
apply (drule_tac y1 = xa in order_le_less_trans [THEN sin_gt_zero])
paulson@15077
  1320
apply (assumption, rule_tac y=y in order_less_le_trans, simp_all) 
paulson@15077
  1321
apply (drule_tac y1 = y in order_le_less_trans [THEN sin_gt_zero], assumption, simp_all) 
paulson@15077
  1322
done
paulson@15077
  1323
    
huffman@23053
  1324
lemma pi_half: "pi/2 = (THE x. 0 \<le> x & x \<le> 2 & cos x = 0)"
paulson@15077
  1325
by (simp add: pi_def)
paulson@15077
  1326
paulson@15077
  1327
lemma cos_pi_half [simp]: "cos (pi / 2) = 0"
huffman@23053
  1328
by (simp add: pi_half cos_is_zero [THEN theI'])
huffman@23053
  1329
huffman@23053
  1330
lemma pi_half_gt_zero [simp]: "0 < pi / 2"
huffman@23053
  1331
apply (rule order_le_neq_trans)
huffman@23053
  1332
apply (simp add: pi_half cos_is_zero [THEN theI'])
huffman@23053
  1333
apply (rule notI, drule arg_cong [where f=cos], simp)
paulson@15077
  1334
done
paulson@15077
  1335
huffman@23053
  1336
lemmas pi_half_neq_zero [simp] = pi_half_gt_zero [THEN less_imp_neq, symmetric]
huffman@23053
  1337
lemmas pi_half_ge_zero [simp] = pi_half_gt_zero [THEN order_less_imp_le]
paulson@15077
  1338
huffman@23053
  1339
lemma pi_half_less_two [simp]: "pi / 2 < 2"
huffman@23053
  1340
apply (rule order_le_neq_trans)
huffman@23053
  1341
apply (simp add: pi_half cos_is_zero [THEN theI'])
huffman@23053
  1342
apply (rule notI, drule arg_cong [where f=cos], simp)
paulson@15077
  1343
done
huffman@23053
  1344
huffman@23053
  1345
lemmas pi_half_neq_two [simp] = pi_half_less_two [THEN less_imp_neq]
huffman@23053
  1346
lemmas pi_half_le_two [simp] =  pi_half_less_two [THEN order_less_imp_le]
paulson@15077
  1347
paulson@15077
  1348
lemma pi_gt_zero [simp]: "0 < pi"
huffman@23053
  1349
by (insert pi_half_gt_zero, simp)
huffman@23053
  1350
huffman@23053
  1351
lemma pi_ge_zero [simp]: "0 \<le> pi"
huffman@23053
  1352
by (rule pi_gt_zero [THEN order_less_imp_le])
paulson@15077
  1353
paulson@15077
  1354
lemma pi_neq_zero [simp]: "pi \<noteq> 0"
huffman@22998
  1355
by (rule pi_gt_zero [THEN less_imp_neq, THEN not_sym])
paulson@15077
  1356
huffman@23053
  1357
lemma pi_not_less_zero [simp]: "\<not> pi < 0"
huffman@23053
  1358
by (simp add: linorder_not_less)
paulson@15077
  1359
huffman@29165
  1360
lemma minus_pi_half_less_zero: "-(pi/2) < 0"
huffman@29165
  1361
by simp
paulson@15077
  1362
paulson@15077
  1363
lemma sin_pi_half [simp]: "sin(pi/2) = 1"
paulson@15077
  1364
apply (cut_tac x = "pi/2" in sin_cos_squared_add2)
paulson@15077
  1365
apply (cut_tac sin_gt_zero [OF pi_half_gt_zero pi_half_less_two])
huffman@23053
  1366
apply (simp add: power2_eq_square)
paulson@15077
  1367
done
paulson@15077
  1368
paulson@15077
  1369
lemma cos_pi [simp]: "cos pi = -1"
nipkow@15539
  1370
by (cut_tac x = "pi/2" and y = "pi/2" in cos_add, simp)
paulson@15077
  1371
paulson@15077
  1372
lemma sin_pi [simp]: "sin pi = 0"
nipkow@15539
  1373
by (cut_tac x = "pi/2" and y = "pi/2" in sin_add, simp)
paulson@15077
  1374
paulson@15077
  1375
lemma sin_cos_eq: "sin x = cos (pi/2 - x)"
paulson@15229
  1376
by (simp add: diff_minus cos_add)
huffman@23053
  1377
declare sin_cos_eq [symmetric, simp]
paulson@15077
  1378
paulson@15077
  1379
lemma minus_sin_cos_eq: "-sin x = cos (x + pi/2)"
paulson@15229
  1380
by (simp add: cos_add)
paulson@15077
  1381
declare minus_sin_cos_eq [symmetric, simp]
paulson@15077
  1382
paulson@15077
  1383
lemma cos_sin_eq: "cos x = sin (pi/2 - x)"
paulson@15229
  1384
by (simp add: diff_minus sin_add)
huffman@23053
  1385
declare cos_sin_eq [symmetric, simp]
paulson@15077
  1386
paulson@15077
  1387
lemma sin_periodic_pi [simp]: "sin (x + pi) = - sin x"
paulson@15229
  1388
by (simp add: sin_add)
paulson@15077
  1389
paulson@15077
  1390
lemma sin_periodic_pi2 [simp]: "sin (pi + x) = - sin x"
paulson@15229
  1391
by (simp add: sin_add)
paulson@15077
  1392
paulson@15077
  1393
lemma cos_periodic_pi [simp]: "cos (x + pi) = - cos x"
paulson@15229
  1394
by (simp add: cos_add)
paulson@15077
  1395
paulson@15077
  1396
lemma sin_periodic [simp]: "sin (x + 2*pi) = sin x"
paulson@15077
  1397
by (simp add: sin_add cos_double)
paulson@15077
  1398
paulson@15077
  1399
lemma cos_periodic [simp]: "cos (x + 2*pi) = cos x"
paulson@15077
  1400
by (simp add: cos_add cos_double)
paulson@15077
  1401
paulson@15077
  1402
lemma cos_npi [simp]: "cos (real n * pi) = -1 ^ n"
paulson@15251
  1403
apply (induct "n")
paulson@15077
  1404
apply (auto simp add: real_of_nat_Suc left_distrib)
paulson@15077
  1405
done
paulson@15077
  1406
paulson@15383
  1407
lemma cos_npi2 [simp]: "cos (pi * real n) = -1 ^ n"
paulson@15383
  1408
proof -
paulson@15383
  1409
  have "cos (pi * real n) = cos (real n * pi)" by (simp only: mult_commute)
paulson@15383
  1410
  also have "... = -1 ^ n" by (rule cos_npi) 
paulson@15383
  1411
  finally show ?thesis .
paulson@15383
  1412
qed
paulson@15383
  1413
paulson@15077
  1414
lemma sin_npi [simp]: "sin (real (n::nat) * pi) = 0"
paulson@15251
  1415
apply (induct "n")
paulson@15077
  1416
apply (auto simp add: real_of_nat_Suc left_distrib)
paulson@15077
  1417
done
paulson@15077
  1418
paulson@15077
  1419
lemma sin_npi2 [simp]: "sin (pi * real (n::nat)) = 0"
paulson@15383
  1420
by (simp add: mult_commute [of pi]) 
paulson@15077
  1421
paulson@15077
  1422
lemma cos_two_pi [simp]: "cos (2 * pi) = 1"
paulson@15077
  1423
by (simp add: cos_double)
paulson@15077
  1424
paulson@15077
  1425
lemma sin_two_pi [simp]: "sin (2 * pi) = 0"
paulson@15229
  1426
by simp
paulson@15077
  1427
paulson@15077
  1428
lemma sin_gt_zero2: "[| 0 < x; x < pi/2 |] ==> 0 < sin x"
paulson@15077
  1429
apply (rule sin_gt_zero, assumption)
paulson@15077
  1430
apply (rule order_less_trans, assumption)
paulson@15077
  1431
apply (rule pi_half_less_two)
paulson@15077
  1432
done
paulson@15077
  1433
paulson@15077
  1434
lemma sin_less_zero: 
paulson@15077
  1435
  assumes lb: "- pi/2 < x" and "x < 0" shows "sin x < 0"
paulson@15077
  1436
proof -
paulson@15077
  1437
  have "0 < sin (- x)" using prems by (simp only: sin_gt_zero2) 
paulson@15077
  1438
  thus ?thesis by simp
paulson@15077
  1439
qed
paulson@15077
  1440
paulson@15077
  1441
lemma pi_less_4: "pi < 4"
paulson@15077
  1442
by (cut_tac pi_half_less_two, auto)
paulson@15077
  1443
paulson@15077
  1444
lemma cos_gt_zero: "[| 0 < x; x < pi/2 |] ==> 0 < cos x"
paulson@15077
  1445
apply (cut_tac pi_less_4)
paulson@15077
  1446
apply (cut_tac f = cos and a = 0 and b = x and y = 0 in IVT2_objl, safe, simp_all)
paulson@15077
  1447
apply (cut_tac cos_is_zero, safe)
paulson@15077
  1448
apply (rename_tac y z)
paulson@15077
  1449
apply (drule_tac x = y in spec)
paulson@15077
  1450
apply (drule_tac x = "pi/2" in spec, simp) 
paulson@15077
  1451
done
paulson@15077
  1452
paulson@15077
  1453
lemma cos_gt_zero_pi: "[| -(pi/2) < x; x < pi/2 |] ==> 0 < cos x"
paulson@15077
  1454
apply (rule_tac x = x and y = 0 in linorder_cases)
paulson@15077
  1455
apply (rule cos_minus [THEN subst])
paulson@15077
  1456
apply (rule cos_gt_zero)
paulson@15077
  1457
apply (auto intro: cos_gt_zero)
paulson@15077
  1458
done
paulson@15077
  1459
 
paulson@15077
  1460
lemma cos_ge_zero: "[| -(pi/2) \<le> x; x \<le> pi/2 |] ==> 0 \<le> cos x"
paulson@15077
  1461
apply (auto simp add: order_le_less cos_gt_zero_pi)
paulson@15077
  1462
apply (subgoal_tac "x = pi/2", auto) 
paulson@15077
  1463
done
paulson@15077
  1464
paulson@15077
  1465
lemma sin_gt_zero_pi: "[| 0 < x; x < pi  |] ==> 0 < sin x"
paulson@15077
  1466
apply (subst sin_cos_eq)
paulson@15077
  1467
apply (rotate_tac 1)
paulson@15077
  1468
apply (drule real_sum_of_halves [THEN ssubst])
paulson@15077
  1469
apply (auto intro!: cos_gt_zero_pi simp del: sin_cos_eq [symmetric])
paulson@15077
  1470
done
paulson@15077
  1471
paulson@15077
  1472
lemma sin_ge_zero: "[| 0 \<le> x; x \<le> pi |] ==> 0 \<le> sin x"
paulson@15077
  1473
by (auto simp add: order_le_less sin_gt_zero_pi)
paulson@15077
  1474
paulson@15077
  1475
lemma cos_total: "[| -1 \<le> y; y \<le> 1 |] ==> EX! x. 0 \<le> x & x \<le> pi & (cos x = y)"
paulson@15077
  1476
apply (subgoal_tac "\<exists>x. 0 \<le> x & x \<le> pi & cos x = y")
paulson@15077
  1477
apply (rule_tac [2] IVT2)
paulson@15077
  1478
apply (auto intro: order_less_imp_le DERIV_isCont DERIV_cos)
paulson@15077
  1479
apply (cut_tac x = xa and y = y in linorder_less_linear)
paulson@15077
  1480
apply (rule ccontr, auto)
paulson@15077
  1481
apply (drule_tac f = cos in Rolle)
paulson@15077
  1482
apply (drule_tac [5] f = cos in Rolle)
paulson@15077
  1483
apply (auto intro: order_less_imp_le DERIV_isCont DERIV_cos
paulson@15077
  1484
            dest!: DERIV_cos [THEN DERIV_unique] 
paulson@15077
  1485
            simp add: differentiable_def)
paulson@15077
  1486
apply (auto dest: sin_gt_zero_pi [OF order_le_less_trans order_less_le_trans])
paulson@15077
  1487
done
paulson@15077
  1488
paulson@15077
  1489
lemma sin_total:
paulson@15077
  1490
     "[| -1 \<le> y; y \<le> 1 |] ==> EX! x. -(pi/2) \<le> x & x \<le> pi/2 & (sin x = y)"
paulson@15077
  1491
apply (rule ccontr)
paulson@15077
  1492
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
  1493
apply (erule contrapos_np)
paulson@15077
  1494
apply (simp del: minus_sin_cos_eq [symmetric])
paulson@15077
  1495
apply (cut_tac y="-y" in cos_total, simp) apply simp 
paulson@15077
  1496
apply (erule ex1E)
paulson@15229
  1497
apply (rule_tac a = "x - (pi/2)" in ex1I)
huffman@23286
  1498
apply (simp (no_asm) add: add_assoc)
paulson@15077
  1499
apply (rotate_tac 3)
paulson@15077
  1500
apply (drule_tac x = "xa + pi/2" in spec, safe, simp_all) 
paulson@15077
  1501
done
paulson@15077
  1502
paulson@15077
  1503
lemma reals_Archimedean4:
paulson@15077
  1504
     "[| 0 < y; 0 \<le> x |] ==> \<exists>n. real n * y \<le> x & x < real (Suc n) * y"
paulson@15077
  1505
apply (auto dest!: reals_Archimedean3)
paulson@15077
  1506
apply (drule_tac x = x in spec, clarify) 
paulson@15077
  1507
apply (subgoal_tac "x < real(LEAST m::nat. x < real m * y) * y")
paulson@15077
  1508
 prefer 2 apply (erule LeastI) 
paulson@15077
  1509
apply (case_tac "LEAST m::nat. x < real m * y", simp) 
paulson@15077
  1510
apply (subgoal_tac "~ x < real nat * y")
paulson@15077
  1511
 prefer 2 apply (rule not_less_Least, simp, force)  
paulson@15077
  1512
done
paulson@15077
  1513
paulson@15077
  1514
(* Pre Isabelle99-2 proof was simpler- numerals arithmetic 
paulson@15077
  1515
   now causes some unwanted re-arrangements of literals!   *)
paulson@15229
  1516
lemma cos_zero_lemma:
paulson@15229
  1517
     "[| 0 \<le> x; cos x = 0 |] ==>  
paulson@15077
  1518
      \<exists>n::nat. ~even n & x = real n * (pi/2)"
paulson@15077
  1519
apply (drule pi_gt_zero [THEN reals_Archimedean4], safe)
paulson@15086
  1520
apply (subgoal_tac "0 \<le> x - real n * pi & 
paulson@15086
  1521
                    (x - real n * pi) \<le> pi & (cos (x - real n * pi) = 0) ")
nipkow@29667
  1522
apply (auto simp add: algebra_simps real_of_nat_Suc)
nipkow@29667
  1523
 prefer 2 apply (simp add: cos_diff)
paulson@15077
  1524
apply (simp add: cos_diff)
paulson@15077
  1525
apply (subgoal_tac "EX! x. 0 \<le> x & x \<le> pi & cos x = 0")
paulson@15077
  1526
apply (rule_tac [2] cos_total, safe)
paulson@15077
  1527
apply (drule_tac x = "x - real n * pi" in spec)
paulson@15077
  1528
apply (drule_tac x = "pi/2" in spec)
paulson@15077
  1529
apply (simp add: cos_diff)
paulson@15229
  1530
apply (rule_tac x = "Suc (2 * n)" in exI)
nipkow@29667
  1531
apply (simp add: real_of_nat_Suc algebra_simps, auto)
paulson@15077
  1532
done
paulson@15077
  1533
paulson@15229
  1534
lemma sin_zero_lemma:
paulson@15229
  1535
     "[| 0 \<le> x; sin x = 0 |] ==>  
paulson@15077
  1536
      \<exists>n::nat. even n & x = real n * (pi/2)"
paulson@15077
  1537
apply (subgoal_tac "\<exists>n::nat. ~ even n & x + pi/2 = real n * (pi/2) ")
paulson@15077
  1538
 apply (clarify, rule_tac x = "n - 1" in exI)
paulson@15077
  1539
 apply (force simp add: odd_Suc_mult_two_ex real_of_nat_Suc left_distrib)
paulson@15085
  1540
apply (rule cos_zero_lemma)
paulson@15085
  1541
apply (simp_all add: add_increasing)  
paulson@15077
  1542
done
paulson@15077
  1543
paulson@15077
  1544
paulson@15229
  1545
lemma cos_zero_iff:
paulson@15229
  1546
     "(cos x = 0) =  
paulson@15077
  1547
      ((\<exists>n::nat. ~even n & (x = real n * (pi/2))) |    
paulson@15077
  1548
       (\<exists>n::nat. ~even n & (x = -(real n * (pi/2)))))"
paulson@15077
  1549
apply (rule iffI)
paulson@15077
  1550
apply (cut_tac linorder_linear [of 0 x], safe)
paulson@15077
  1551
apply (drule cos_zero_lemma, assumption+)
paulson@15077
  1552
apply (cut_tac x="-x" in cos_zero_lemma, simp, simp) 
paulson@15077
  1553
apply (force simp add: minus_equation_iff [of x]) 
paulson@15077
  1554
apply (auto simp only: odd_Suc_mult_two_ex real_of_nat_Suc left_distrib) 
nipkow@15539
  1555
apply (auto simp add: cos_add)
paulson@15077
  1556
done
paulson@15077
  1557
paulson@15077
  1558
(* ditto: but to a lesser extent *)
paulson@15229
  1559
lemma sin_zero_iff:
paulson@15229
  1560
     "(sin x = 0) =  
paulson@15077
  1561
      ((\<exists>n::nat. even n & (x = real n * (pi/2))) |    
paulson@15077
  1562
       (\<exists>n::nat. even n & (x = -(real n * (pi/2)))))"
paulson@15077
  1563
apply (rule iffI)
paulson@15077
  1564
apply (cut_tac linorder_linear [of 0 x], safe)
paulson@15077
  1565
apply (drule sin_zero_lemma, assumption+)
paulson@15077
  1566
apply (cut_tac x="-x" in sin_zero_lemma, simp, simp, safe)
paulson@15077
  1567
apply (force simp add: minus_equation_iff [of x]) 
nipkow@15539
  1568
apply (auto simp add: even_mult_two_ex)
paulson@15077
  1569
done
paulson@15077
  1570
paulson@15077
  1571
huffman@29164
  1572
subsection {* Tangent *}
paulson@15077
  1573
huffman@23043
  1574
definition
huffman@23043
  1575
  tan :: "real => real" where
huffman@23043
  1576
  "tan x = (sin x)/(cos x)"
huffman@23043
  1577
paulson@15077
  1578
lemma tan_zero [simp]: "tan 0 = 0"
paulson@15077
  1579
by (simp add: tan_def)
paulson@15077
  1580
paulson@15077
  1581
lemma tan_pi [simp]: "tan pi = 0"
paulson@15077
  1582
by (simp add: tan_def)
paulson@15077
  1583
paulson@15077
  1584
lemma tan_npi [simp]: "tan (real (n::nat) * pi) = 0"
paulson@15077
  1585
by (simp add: tan_def)
paulson@15077
  1586
paulson@15077
  1587
lemma tan_minus [simp]: "tan (-x) = - tan x"
paulson@15077
  1588
by (simp add: tan_def minus_mult_left)
paulson@15077
  1589
paulson@15077
  1590
lemma tan_periodic [simp]: "tan (x + 2*pi) = tan x"
paulson@15077
  1591
by (simp add: tan_def)
paulson@15077
  1592
paulson@15077
  1593
lemma lemma_tan_add1: 
paulson@15077
  1594
      "[| cos x \<noteq> 0; cos y \<noteq> 0 |]  
paulson@15077
  1595
        ==> 1 - tan(x)*tan(y) = cos (x + y)/(cos x * cos y)"
paulson@15229
  1596
apply (simp add: tan_def divide_inverse)
paulson@15229
  1597
apply (auto simp del: inverse_mult_distrib 
paulson@15229
  1598
            simp add: inverse_mult_distrib [symmetric] mult_ac)
paulson@15077
  1599
apply (rule_tac c1 = "cos x * cos y" in real_mult_right_cancel [THEN subst])
paulson@15229
  1600
apply (auto simp del: inverse_mult_distrib 
paulson@15229
  1601
            simp add: mult_assoc left_diff_distrib cos_add)
nipkow@29667
  1602
done
paulson@15077
  1603
paulson@15077
  1604
lemma add_tan_eq: 
paulson@15077
  1605
      "[| cos x \<noteq> 0; cos y \<noteq> 0 |]  
paulson@15077
  1606
       ==> tan x + tan y = sin(x + y)/(cos x * cos y)"
paulson@15229
  1607
apply (simp add: tan_def)
paulson@15077
  1608
apply (rule_tac c1 = "cos x * cos y" in real_mult_right_cancel [THEN subst])
paulson@15077
  1609
apply (auto simp add: mult_assoc left_distrib)
nipkow@15539
  1610
apply (simp add: sin_add)
paulson@15077
  1611
done
paulson@15077
  1612
paulson@15229
  1613
lemma tan_add:
paulson@15229
  1614
     "[| cos x \<noteq> 0; cos y \<noteq> 0; cos (x + y) \<noteq> 0 |]  
paulson@15077
  1615
      ==> tan(x + y) = (tan(x) + tan(y))/(1 - tan(x) * tan(y))"
paulson@15077
  1616
apply (simp (no_asm_simp) add: add_tan_eq lemma_tan_add1)
paulson@15077
  1617
apply (simp add: tan_def)
paulson@15077
  1618
done
paulson@15077
  1619
paulson@15229
  1620
lemma tan_double:
paulson@15229
  1621
     "[| cos x \<noteq> 0; cos (2 * x) \<noteq> 0 |]  
paulson@15077
  1622
      ==> tan (2 * x) = (2 * tan x)/(1 - (tan(x) ^ 2))"
paulson@15077
  1623
apply (insert tan_add [of x x]) 
paulson@15077
  1624
apply (simp add: mult_2 [symmetric])  
paulson@15077
  1625
apply (auto simp add: numeral_2_eq_2)
paulson@15077
  1626
done
paulson@15077
  1627
paulson@15077
  1628
lemma tan_gt_zero: "[| 0 < x; x < pi/2 |] ==> 0 < tan x"
paulson@15229
  1629
by (simp add: tan_def zero_less_divide_iff sin_gt_zero2 cos_gt_zero_pi) 
paulson@15077
  1630
paulson@15077
  1631
lemma tan_less_zero: 
paulson@15077
  1632
  assumes lb: "- pi/2 < x" and "x < 0" shows "tan x < 0"
paulson@15077
  1633
proof -
paulson@15077
  1634
  have "0 < tan (- x)" using prems by (simp only: tan_gt_zero) 
paulson@15077
  1635
  thus ?thesis by simp
paulson@15077
  1636
qed
paulson@15077
  1637
paulson@15077
  1638
lemma lemma_DERIV_tan:
paulson@15077
  1639
     "cos x \<noteq> 0 ==> DERIV (%x. sin(x)/cos(x)) x :> inverse((cos x)\<twosuperior>)"
paulson@15077
  1640
apply (rule lemma_DERIV_subst)
paulson@15077
  1641
apply (best intro!: DERIV_intros intro: DERIV_chain2) 
paulson@15079
  1642
apply (auto simp add: divide_inverse numeral_2_eq_2)
paulson@15077
  1643
done
paulson@15077
  1644
paulson@15077
  1645
lemma DERIV_tan [simp]: "cos x \<noteq> 0 ==> DERIV tan x :> inverse((cos x)\<twosuperior>)"
paulson@15077
  1646
by (auto dest: lemma_DERIV_tan simp add: tan_def [symmetric])
paulson@15077
  1647
huffman@23045
  1648
lemma isCont_tan [simp]: "cos x \<noteq> 0 ==> isCont tan x"
huffman@23045
  1649
by (rule DERIV_tan [THEN DERIV_isCont])
huffman@23045
  1650
paulson@15077
  1651
lemma LIM_cos_div_sin [simp]: "(%x. cos(x)/sin(x)) -- pi/2 --> 0"
paulson@15077
  1652
apply (subgoal_tac "(\<lambda>x. cos x * inverse (sin x)) -- pi * inverse 2 --> 0*1")
paulson@15229
  1653
apply (simp add: divide_inverse [symmetric])
huffman@22613
  1654
apply (rule LIM_mult)
paulson@15077
  1655
apply (rule_tac [2] inverse_1 [THEN subst])
paulson@15077
  1656
apply (rule_tac [2] LIM_inverse)
paulson@15077
  1657
apply (simp_all add: divide_inverse [symmetric]) 
paulson@15077
  1658
apply (simp_all only: isCont_def [symmetric] cos_pi_half [symmetric] sin_pi_half [symmetric]) 
paulson@15077
  1659
apply (blast intro!: DERIV_isCont DERIV_sin DERIV_cos)+
paulson@15077
  1660
done
paulson@15077
  1661
paulson@15077
  1662
lemma lemma_tan_total: "0 < y ==> \<exists>x. 0 < x & x < pi/2 & y < tan x"
paulson@15077
  1663
apply (cut_tac LIM_cos_div_sin)
paulson@15077
  1664
apply (simp only: LIM_def)
paulson@15077
  1665
apply (drule_tac x = "inverse y" in spec, safe, force)
paulson@15077
  1666
apply (drule_tac ?d1.0 = s in pi_half_gt_zero [THEN [2] real_lbound_gt_zero], safe)
paulson@15229
  1667
apply (rule_tac x = "(pi/2) - e" in exI)
paulson@15077
  1668
apply (simp (no_asm_simp))
paulson@15229
  1669
apply (drule_tac x = "(pi/2) - e" in spec)
paulson@15229
  1670
apply (auto simp add: tan_def)
paulson@15077
  1671
apply (rule inverse_less_iff_less [THEN iffD1])
paulson@15079
  1672
apply (auto simp add: divide_inverse)
paulson@15229
  1673
apply (rule real_mult_order) 
paulson@15229
  1674
apply (subgoal_tac [3] "0 < sin e & 0 < cos e")
paulson@15229
  1675
apply (auto intro: cos_gt_zero sin_gt_zero2 simp add: mult_commute) 
paulson@15077
  1676
done
paulson@15077
  1677
paulson@15077
  1678
lemma tan_total_pos: "0 \<le> y ==> \<exists>x. 0 \<le> x & x < pi/2 & tan x = y"
huffman@22998
  1679
apply (frule order_le_imp_less_or_eq, safe)
paulson@15077
  1680
 prefer 2 apply force
paulson@15077
  1681
apply (drule lemma_tan_total, safe)
paulson@15077
  1682
apply (cut_tac f = tan and a = 0 and b = x and y = y in IVT_objl)
paulson@15077
  1683
apply (auto intro!: DERIV_tan [THEN DERIV_isCont])
paulson@15077
  1684
apply (drule_tac y = xa in order_le_imp_less_or_eq)
paulson@15077
  1685
apply (auto dest: cos_gt_zero)
paulson@15077
  1686
done
paulson@15077
  1687
paulson@15077
  1688
lemma lemma_tan_total1: "\<exists>x. -(pi/2) < x & x < (pi/2) & tan x = y"
paulson@15077
  1689
apply (cut_tac linorder_linear [of 0 y], safe)
paulson@15077
  1690
apply (drule tan_total_pos)
paulson@15077
  1691
apply (cut_tac [2] y="-y" in tan_total_pos, safe)
paulson@15077
  1692
apply (rule_tac [3] x = "-x" in exI)
paulson@15077
  1693
apply (auto intro!: exI)
paulson@15077
  1694
done
paulson@15077
  1695
paulson@15077
  1696
lemma tan_total: "EX! x. -(pi/2) < x & x < (pi/2) & tan x = y"
paulson@15077
  1697
apply (cut_tac y = y in lemma_tan_total1, auto)
paulson@15077
  1698
apply (cut_tac x = xa and y = y in linorder_less_linear, auto)
paulson@15077
  1699
apply (subgoal_tac [2] "\<exists>z. y < z & z < xa & DERIV tan z :> 0")
paulson@15077
  1700
apply (subgoal_tac "\<exists>z. xa < z & z < y & DERIV tan z :> 0")
paulson@15077
  1701
apply (rule_tac [4] Rolle)
paulson@15077
  1702
apply (rule_tac [2] Rolle)
paulson@15077
  1703
apply (auto intro!: DERIV_tan DERIV_isCont exI 
paulson@15077
  1704
            simp add: differentiable_def)
paulson@15077
  1705
txt{*Now, simulate TRYALL*}
paulson@15077
  1706
apply (rule_tac [!] DERIV_tan asm_rl)
paulson@15077
  1707
apply (auto dest!: DERIV_unique [OF _ DERIV_tan]
huffman@22998
  1708
	    simp add: cos_gt_zero_pi [THEN less_imp_neq, THEN not_sym]) 
paulson@15077
  1709
done
paulson@15077
  1710
huffman@23043
  1711
huffman@23043
  1712
subsection {* Inverse Trigonometric Functions *}
huffman@23043
  1713
huffman@23043
  1714
definition
huffman@23043
  1715
  arcsin :: "real => real" where
huffman@23043
  1716
  "arcsin y = (THE x. -(pi/2) \<le> x & x \<le> pi/2 & sin x = y)"
huffman@23043
  1717
huffman@23043
  1718
definition
huffman@23043
  1719
  arccos :: "real => real" where
huffman@23043
  1720
  "arccos y = (THE x. 0 \<le> x & x \<le> pi & cos x = y)"
huffman@23043
  1721
huffman@23043
  1722
definition     
huffman@23043
  1723
  arctan :: "real => real" where
huffman@23043
  1724
  "arctan y = (THE x. -(pi/2) < x & x < pi/2 & tan x = y)"
huffman@23043
  1725
paulson@15229
  1726
lemma arcsin:
paulson@15229
  1727
     "[| -1 \<le> y; y \<le> 1 |]  
paulson@15077
  1728
      ==> -(pi/2) \<le> arcsin y &  
paulson@15077
  1729
           arcsin y \<le> pi/2 & sin(arcsin y) = y"
huffman@23011
  1730
unfolding arcsin_def by (rule theI' [OF sin_total])
huffman@23011
  1731
huffman@23011
  1732
lemma arcsin_pi:
huffman@23011
  1733
     "[| -1 \<le> y; y \<le> 1 |]  
huffman@23011
  1734
      ==> -(pi/2) \<le> arcsin y & arcsin y \<le> pi & sin(arcsin y) = y"
huffman@23011
  1735
apply (drule (1) arcsin)
huffman@23011
  1736
apply (force intro: order_trans)
paulson@15077
  1737
done
paulson@15077
  1738
paulson@15077
  1739
lemma sin_arcsin [simp]: "[| -1 \<le> y; y \<le> 1 |] ==> sin(arcsin y) = y"
paulson@15077
  1740
by (blast dest: arcsin)
paulson@15077
  1741
      
paulson@15077
  1742
lemma arcsin_bounded:
paulson@15077
  1743
     "[| -1 \<le> y; y \<le> 1 |] ==> -(pi/2) \<le> arcsin y & arcsin y \<le> pi/2"
paulson@15077
  1744
by (blast dest: arcsin)
paulson@15077
  1745
paulson@15077
  1746
lemma arcsin_lbound: "[| -1 \<le> y; y \<le> 1 |] ==> -(pi/2) \<le> arcsin y"
paulson@15077
  1747
by (blast dest: arcsin)
paulson@15077
  1748
paulson@15077
  1749
lemma arcsin_ubound: "[| -1 \<le> y; y \<le> 1 |] ==> arcsin y \<le> pi/2"
paulson@15077
  1750
by (blast dest: arcsin)
paulson@15077
  1751
paulson@15077
  1752
lemma arcsin_lt_bounded:
paulson@15077
  1753
     "[| -1 < y; y < 1 |] ==> -(pi/2) < arcsin y & arcsin y < pi/2"
paulson@15077
  1754
apply (frule order_less_imp_le)
paulson@15077
  1755
apply (frule_tac y = y in order_less_imp_le)
paulson@15077
  1756
apply (frule arcsin_bounded)
paulson@15077
  1757
apply (safe, simp)
paulson@15077
  1758
apply (drule_tac y = "arcsin y" in order_le_imp_less_or_eq)
paulson@15077
  1759
apply (drule_tac [2] y = "pi/2" in order_le_imp_less_or_eq, safe)
paulson@15077
  1760
apply (drule_tac [!] f = sin in arg_cong, auto)
paulson@15077
  1761
done
paulson@15077
  1762
paulson@15077
  1763
lemma arcsin_sin: "[|-(pi/2) \<le> x; x \<le> pi/2 |] ==> arcsin(sin x) = x"
paulson@15077
  1764
apply (unfold arcsin_def)
huffman@23011
  1765
apply (rule the1_equality)
paulson@15077
  1766
apply (rule sin_total, auto)
paulson@15077
  1767
done
paulson@15077
  1768
huffman@22975
  1769
lemma arccos:
paulson@15229
  1770
     "[| -1 \<le> y; y \<le> 1 |]  
huffman@22975
  1771
      ==> 0 \<le> arccos y & arccos y \<le> pi & cos(arccos y) = y"
huffman@23011
  1772
unfolding arccos_def by (rule theI' [OF cos_total])
paulson@15077
  1773
huffman@22975
  1774
lemma cos_arccos [simp]: "[| -1 \<le> y; y \<le> 1 |] ==> cos(arccos y) = y"
huffman@22975
  1775
by (blast dest: arccos)
paulson@15077
  1776
      
huffman@22975
  1777
lemma arccos_bounded: "[| -1 \<le> y; y \<le> 1 |] ==> 0 \<le> arccos y & arccos y \<le> pi"
huffman@22975
  1778
by (blast dest: arccos)
paulson@15077
  1779
huffman@22975
  1780
lemma arccos_lbound: "[| -1 \<le> y; y \<le> 1 |] ==> 0 \<le> arccos y"
huffman@22975
  1781
by (blast dest: arccos)
paulson@15077
  1782
huffman@22975
  1783
lemma arccos_ubound: "[| -1 \<le> y; y \<le> 1 |] ==> arccos y \<le> pi"
huffman@22975
  1784
by (blast dest: arccos)
paulson@15077
  1785
huffman@22975
  1786
lemma arccos_lt_bounded:
paulson@15229
  1787
     "[| -1 < y; y < 1 |]  
huffman@22975
  1788
      ==> 0 < arccos y & arccos y < pi"
paulson@15077
  1789
apply (frule order_less_imp_le)
paulson@15077
  1790
apply (frule_tac y = y in order_less_imp_le)
huffman@22975
  1791
apply (frule arccos_bounded, auto)
huffman@22975
  1792
apply (drule_tac y = "arccos y" in order_le_imp_less_or_eq)
paulson@15077
  1793
apply (drule_tac [2] y = pi in order_le_imp_less_or_eq, auto)
paulson@15077
  1794
apply (drule_tac [!] f = cos in arg_cong, auto)
paulson@15077
  1795
done
paulson@15077
  1796
huffman@22975
  1797
lemma arccos_cos: "[|0 \<le> x; x \<le> pi |] ==> arccos(cos x) = x"
huffman@22975
  1798
apply (simp add: arccos_def)
huffman@23011
  1799
apply (auto intro!: the1_equality cos_total)
paulson@15077
  1800
done
paulson@15077
  1801
huffman@22975
  1802
lemma arccos_cos2: "[|x \<le> 0; -pi \<le> x |] ==> arccos(cos x) = -x"
huffman@22975
  1803
apply (simp add: arccos_def)
huffman@23011
  1804
apply (auto intro!: the1_equality cos_total)
paulson@15077
  1805
done
paulson@15077
  1806
huffman@23045
  1807
lemma cos_arcsin: "\<lbrakk>-1 \<le> x; x \<le> 1\<rbrakk> \<Longrightarrow> cos (arcsin x) = sqrt (1 - x\<twosuperior>)"
huffman@23045
  1808
apply (subgoal_tac "x\<twosuperior> \<le> 1")
huffman@23052
  1809
apply (rule power2_eq_imp_eq)
huffman@23045
  1810
apply (simp add: cos_squared_eq)
huffman@23045
  1811
apply (rule cos_ge_zero)
huffman@23045
  1812
apply (erule (1) arcsin_lbound)
huffman@23045
  1813
apply (erule (1) arcsin_ubound)
huffman@23045
  1814
apply simp
huffman@23045
  1815
apply (subgoal_tac "\<bar>x\<bar>\<twosuperior> \<le> 1\<twosuperior>", simp)
huffman@23045
  1816
apply (rule power_mono, simp, simp)
huffman@23045
  1817
done
huffman@23045
  1818
huffman@23045
  1819
lemma sin_arccos: "\<lbrakk>-1 \<le> x; x \<le> 1\<rbrakk> \<Longrightarrow> sin (arccos x) = sqrt (1 - x\<twosuperior>)"
huffman@23045
  1820
apply (subgoal_tac "x\<twosuperior> \<le> 1")
huffman@23052
  1821
apply (rule power2_eq_imp_eq)
huffman@23045
  1822
apply (simp add: sin_squared_eq)
huffman@23045
  1823
apply (rule sin_ge_zero)
huffman@23045
  1824
apply (erule (1) arccos_lbound)
huffman@23045
  1825
apply (erule (1) arccos_ubound)
huffman@23045
  1826
apply simp
huffman@23045
  1827
apply (subgoal_tac "\<bar>x\<bar>\<twosuperior> \<le> 1\<twosuperior>", simp)
huffman@23045
  1828
apply (rule power_mono, simp, simp)
huffman@23045
  1829
done
huffman@23045
  1830
paulson@15077
  1831
lemma arctan [simp]:
paulson@15077
  1832
     "- (pi/2) < arctan y  & arctan y < pi/2 & tan (arctan y) = y"
huffman@23011
  1833
unfolding arctan_def by (rule theI' [OF tan_total])
paulson@15077
  1834
paulson@15077
  1835
lemma tan_arctan: "tan(arctan y) = y"
paulson@15077
  1836
by auto
paulson@15077
  1837
paulson@15077
  1838
lemma arctan_bounded: "- (pi/2) < arctan y  & arctan y < pi/2"
paulson@15077
  1839
by (auto simp only: arctan)
paulson@15077
  1840
paulson@15077
  1841
lemma arctan_lbound: "- (pi/2) < arctan y"
paulson@15077
  1842
by auto
paulson@15077
  1843
paulson@15077
  1844
lemma arctan_ubound: "arctan y < pi/2"
paulson@15077
  1845
by (auto simp only: arctan)
paulson@15077
  1846
paulson@15077
  1847
lemma arctan_tan: 
paulson@15077
  1848
      "[|-(pi/2) < x; x < pi/2 |] ==> arctan(tan x) = x"
paulson@15077
  1849
apply (unfold arctan_def)
huffman@23011
  1850
apply (rule the1_equality)
paulson@15077
  1851
apply (rule tan_total, auto)
paulson@15077
  1852
done
paulson@15077
  1853
paulson@15077
  1854
lemma arctan_zero_zero [simp]: "arctan 0 = 0"
paulson@15077
  1855
by (insert arctan_tan [of 0], simp)
paulson@15077
  1856
paulson@15077
  1857
lemma cos_arctan_not_zero [simp]: "cos(arctan x) \<noteq> 0"
paulson@15077
  1858
apply (auto simp add: cos_zero_iff)
paulson@15077
  1859
apply (case_tac "n")
paulson@15077
  1860
apply (case_tac [3] "n")
paulson@15077
  1861
apply (cut_tac [2] y = x in arctan_ubound)
paulson@15077
  1862
apply (cut_tac [4] y = x in arctan_lbound) 
paulson@15077
  1863
apply (auto simp add: real_of_nat_Suc left_distrib mult_less_0_iff)
paulson@15077
  1864
done
paulson@15077
  1865
paulson@15077
  1866
lemma tan_sec: "cos x \<noteq> 0 ==> 1 + tan(x) ^ 2 = inverse(cos x) ^ 2"
paulson@15077
  1867
apply (rule power_inverse [THEN subst])
paulson@15077
  1868
apply (rule_tac c1 = "(cos x)\<twosuperior>" in real_mult_right_cancel [THEN iffD1])
huffman@22960
  1869
apply (auto dest: field_power_not_zero
huffman@20516
  1870
        simp add: power_mult_distrib left_distrib power_divide tan_def 
paulson@15077
  1871
                  mult_assoc power_inverse [symmetric] 
paulson@15077
  1872
        simp del: realpow_Suc)
paulson@15077
  1873
done
paulson@15077
  1874
huffman@23045
  1875
lemma isCont_inverse_function2:
huffman@23045
  1876
  fixes f g :: "real \<Rightarrow> real" shows
huffman@23045
  1877
  "\<lbrakk>a < x; x < b;
huffman@23045
  1878
    \<forall>z. a \<le> z \<and> z \<le> b \<longrightarrow> g (f z) = z;
huffman@23045
  1879
    \<forall>z. a \<le> z \<and> z \<le> b \<longrightarrow> isCont f z\<rbrakk>
huffman@23045
  1880
   \<Longrightarrow> isCont g (f x)"
huffman@23045
  1881
apply (rule isCont_inverse_function
huffman@23045
  1882
       [where f=f and d="min (x - a) (b - x)"])
huffman@23045
  1883
apply (simp_all add: abs_le_iff)
huffman@23045
  1884
done
huffman@23045
  1885
huffman@23045
  1886
lemma isCont_arcsin: "\<lbrakk>-1 < x; x < 1\<rbrakk> \<Longrightarrow> isCont arcsin x"
huffman@23045
  1887
apply (subgoal_tac "isCont arcsin (sin (arcsin x))", simp)
huffman@23045
  1888
apply (rule isCont_inverse_function2 [where f=sin])
huffman@23045
  1889
apply (erule (1) arcsin_lt_bounded [THEN conjunct1])
huffman@23045
  1890
apply (erule (1) arcsin_lt_bounded [THEN conjunct2])
huffman@23045
  1891
apply (fast intro: arcsin_sin, simp)
huffman@23045
  1892
done
huffman@23045
  1893
huffman@23045
  1894
lemma isCont_arccos: "\<lbrakk>-1 < x; x < 1\<rbrakk> \<Longrightarrow> isCont arccos x"
huffman@23045
  1895
apply (subgoal_tac "isCont arccos (cos (arccos x))", simp)
huffman@23045
  1896
apply (rule isCont_inverse_function2 [where f=cos])
huffman@23045
  1897
apply (erule (1) arccos_lt_bounded [THEN conjunct1])
huffman@23045
  1898
apply (erule (1) arccos_lt_bounded [THEN conjunct2])
huffman@23045
  1899
apply (fast intro: arccos_cos, simp)
huffman@23045
  1900
done
huffman@23045
  1901
huffman@23045
  1902
lemma isCont_arctan: "isCont arctan x"
huffman@23045
  1903
apply (rule arctan_lbound [of x, THEN dense, THEN exE], clarify)
huffman@23045
  1904
apply (rule arctan_ubound [of x, THEN dense, THEN exE], clarify)
huffman@23045
  1905
apply (subgoal_tac "isCont arctan (tan (arctan x))", simp)
huffman@23045
  1906
apply (erule (1) isCont_inverse_function2 [where f=tan])
huffman@23045
  1907
apply (clarify, rule arctan_tan)
huffman@23045
  1908
apply (erule (1) order_less_le_trans)
huffman@23045
  1909
apply (erule (1) order_le_less_trans)
huffman@23045
  1910
apply (clarify, rule isCont_tan)
huffman@23045
  1911
apply (rule less_imp_neq [symmetric])
huffman@23045
  1912
apply (rule cos_gt_zero_pi)
huffman@23045
  1913
apply (erule (1) order_less_le_trans)
huffman@23045
  1914
apply (erule (1) order_le_less_trans)
huffman@23045
  1915
done
huffman@23045
  1916
huffman@23045
  1917
lemma DERIV_arcsin:
huffman@23045
  1918
  "\<lbrakk>-1 < x; x < 1\<rbrakk> \<Longrightarrow> DERIV arcsin x :> inverse (sqrt (1 - x\<twosuperior>))"
huffman@23045
  1919
apply (rule DERIV_inverse_function [where f=sin and a="-1" and b="1"])
huffman@23045
  1920
apply (rule lemma_DERIV_subst [OF DERIV_sin])
huffman@23045
  1921
apply (simp add: cos_arcsin)
huffman@23045
  1922
apply (subgoal_tac "\<bar>x\<bar>\<twosuperior> < 1\<twosuperior>", simp)
huffman@23045
  1923
apply (rule power_strict_mono, simp, simp, simp)
huffman@23045
  1924
apply assumption
huffman@23045
  1925
apply assumption
huffman@23045
  1926
apply simp
huffman@23045
  1927
apply (erule (1) isCont_arcsin)
huffman@23045
  1928
done
huffman@23045
  1929
huffman@23045
  1930
lemma DERIV_arccos:
huffman@23045
  1931
  "\<lbrakk>-1 < x; x < 1\<rbrakk> \<Longrightarrow> DERIV arccos x :> inverse (- sqrt (1 - x\<twosuperior>))"
huffman@23045
  1932
apply (rule DERIV_inverse_function [where f=cos and a="-1" and b="1"])
huffman@23045
  1933
apply (rule lemma_DERIV_subst [OF DERIV_cos])
huffman@23045
  1934
apply (simp add: sin_arccos)
huffman@23045
  1935
apply (subgoal_tac "\<bar>x\<bar>\<twosuperior> < 1\<twosuperior>", simp)
huffman@23045
  1936
apply (rule power_strict_mono, simp, simp, simp)
huffman@23045
  1937
apply assumption
huffman@23045
  1938
apply assumption
huffman@23045
  1939
apply simp
huffman@23045
  1940
apply (erule (1) isCont_arccos)
huffman@23045
  1941
done
huffman@23045
  1942
huffman@23045
  1943
lemma DERIV_arctan: "DERIV arctan x :> inverse (1 + x\<twosuperior>)"
huffman@23045
  1944
apply (rule DERIV_inverse_function [where f=tan and a="x - 1" and b="x + 1"])
huffman@23045
  1945
apply (rule lemma_DERIV_subst [OF DERIV_tan])
huffman@23045
  1946
apply (rule cos_arctan_not_zero)
huffman@23045
  1947
apply (simp add: power_inverse tan_sec [symmetric])
huffman@23045
  1948
apply (subgoal_tac "0 < 1 + x\<twosuperior>", simp)
huffman@23045
  1949
apply (simp add: add_pos_nonneg)
huffman@23045
  1950
apply (simp, simp, simp, rule isCont_arctan)
huffman@23045
  1951
done
huffman@23045
  1952
huffman@23045
  1953
huffman@23043
  1954
subsection {* More Theorems about Sin and Cos *}
huffman@23043
  1955
huffman@23052
  1956
lemma cos_45: "cos (pi / 4) = sqrt 2 / 2"
huffman@23052
  1957
proof -
huffman@23052
  1958
  let ?c = "cos (pi / 4)" and ?s = "sin (pi / 4)"
huffman@23052
  1959
  have nonneg: "0 \<le> ?c"
huffman@23052
  1960
    by (rule cos_ge_zero, rule order_trans [where y=0], simp_all)
huffman@23052
  1961
  have "0 = cos (pi / 4 + pi / 4)"
huffman@23052
  1962
    by simp
huffman@23052
  1963
  also have "cos (pi / 4 + pi / 4) = ?c\<twosuperior> - ?s\<twosuperior>"
huffman@23052
  1964
    by (simp only: cos_add power2_eq_square)
huffman@23052
  1965
  also have "\<dots> = 2 * ?c\<twosuperior> - 1"
huffman@23052
  1966
    by (simp add: sin_squared_eq)
huffman@23052
  1967
  finally have "?c\<twosuperior> = (sqrt 2 / 2)\<twosuperior>"
huffman@23052
  1968
    by (simp add: power_divide)
huffman@23052
  1969
  thus ?thesis
huffman@23052
  1970
    using nonneg by (rule power2_eq_imp_eq) simp
huffman@23052
  1971
qed
huffman@23052
  1972
huffman@23052
  1973
lemma cos_30: "cos (pi / 6) = sqrt 3 / 2"
huffman@23052
  1974
proof -
huffman@23052
  1975
  let ?c = "cos (pi / 6)" and ?s = "sin (pi / 6)"
huffman@23052
  1976
  have pos_c: "0 < ?c"
huffman@23052
  1977
    by (rule cos_gt_zero, simp, simp)
huffman@23052
  1978
  have "0 = cos (pi / 6 + pi / 6 + pi / 6)"
huffman@23066
  1979
    by simp
huffman@23052
  1980
  also have "\<dots> = (?c * ?c - ?s * ?s) * ?c - (?s * ?c + ?c * ?s) * ?s"
huffman@23052
  1981
    by (simp only: cos_add sin_add)
huffman@23052
  1982
  also have "\<dots> = ?c * (?c\<twosuperior> - 3 * ?s\<twosuperior>)"
nipkow@29667
  1983
    by (simp add: algebra_simps power2_eq_square)
huffman@23052
  1984
  finally have "?c\<twosuperior> = (sqrt 3 / 2)\<twosuperior>"
huffman@23052
  1985
    using pos_c by (simp add: sin_squared_eq power_divide)
huffman@23052
  1986
  thus ?thesis
huffman@23052
  1987
    using pos_c [THEN order_less_imp_le]
huffman@23052
  1988
    by (rule power2_eq_imp_eq) simp
huffman@23052
  1989
qed
huffman@23052
  1990
huffman@23052
  1991
lemma sin_45: "sin (pi / 4) = sqrt 2 / 2"
huffman@23052
  1992
proof -
huffman@23052
  1993
  have "sin (pi / 4) = cos (pi / 2 - pi / 4)" by (rule sin_cos_eq)
huffman@23052
  1994
  also have "pi / 2 - pi / 4 = pi / 4" by simp
huffman@23052
  1995
  also have "cos (pi / 4) = sqrt 2 / 2" by (rule cos_45)
huffman@23052
  1996
  finally show ?thesis .
huffman@23052
  1997
qed
huffman@23052
  1998
huffman@23052
  1999
lemma sin_60: "sin (pi / 3) = sqrt 3 / 2"
huffman@23052
  2000
proof -
huffman@23052
  2001
  have "sin (pi / 3) = cos (pi / 2 - pi / 3)" by (rule sin_cos_eq)
huffman@23052
  2002
  also have "pi / 2 - pi / 3 = pi / 6" by simp
huffman@23052
  2003
  also have "cos (pi / 6) = sqrt 3 / 2" by (rule cos_30)
huffman@23052
  2004
  finally show ?thesis .
huffman@23052
  2005
qed
huffman@23052
  2006
huffman@23052
  2007
lemma cos_60: "cos (pi / 3) = 1 / 2"
huffman@23052
  2008
apply (rule power2_eq_imp_eq)
huffman@23052
  2009
apply (simp add: cos_squared_eq sin_60 power_divide)
huffman@23052
  2010
apply (rule cos_ge_zero, rule order_trans [where y=0], simp_all)
huffman@23052
  2011
done
huffman@23052
  2012
huffman@23052
  2013
lemma sin_30: "sin (pi / 6) = 1 / 2"
huffman@23052
  2014
proof -
huffman@23052
  2015
  have "sin (pi / 6) = cos (pi / 2 - pi / 6)" by (rule sin_cos_eq)
huffman@23066
  2016
  also have "pi / 2 - pi / 6 = pi / 3" by simp
huffman@23052
  2017
  also have "cos (pi / 3) = 1 / 2" by (rule cos_60)
huffman@23052
  2018
  finally show ?thesis .
huffman@23052
  2019
qed
huffman@23052
  2020
huffman@23052
  2021
lemma tan_30: "tan (pi / 6) = 1 / sqrt 3"
huffman@23052
  2022
unfolding tan_def by (simp add: sin_30 cos_30)
huffman@23052
  2023
huffman@23052
  2024
lemma tan_45: "tan (pi / 4) = 1"
huffman@23052
  2025
unfolding tan_def by (simp add: sin_45 cos_45)
huffman@23052
  2026
huffman@23052
  2027
lemma tan_60: "tan (pi / 3) = sqrt 3"
huffman@23052
  2028
unfolding tan_def by (simp add: sin_60 cos_60)
huffman@23052
  2029
paulson@15085
  2030
text{*NEEDED??*}
paulson@15229
  2031
lemma [simp]:
paulson@15229
  2032
     "sin (x + 1 / 2 * real (Suc m) * pi) =  
paulson@15229
  2033
      cos (x + 1 / 2 * real  (m) * pi)"
paulson@15229
  2034
by (simp only: cos_add sin_add real_of_nat_Suc left_distrib right_distrib, auto)
paulson@15077
  2035
paulson@15085
  2036
text{*NEEDED??*}
paulson@15229
  2037
lemma [simp]:
paulson@15229
  2038
     "sin (x + real (Suc m) * pi / 2) =  
paulson@15229
  2039
      cos (x + real (m) * pi / 2)"
paulson@15229
  2040
by (simp only: cos_add sin_add real_of_nat_Suc add_divide_distrib left_distrib, auto)
paulson@15077
  2041
paulson@15077
  2042
lemma DERIV_sin_add [simp]: "DERIV (%x. sin (x + k)) xa :> cos (xa + k)"
paulson@15077
  2043
apply (rule lemma_DERIV_subst)
paulson@15077
  2044
apply (rule_tac f = sin and g = "%x. x + k" in DERIV_chain2)
paulson@15077
  2045
apply (best intro!: DERIV_intros intro: DERIV_chain2)+
paulson@15077
  2046
apply (simp (no_asm))
paulson@15077
  2047
done
paulson@15077
  2048
paulson@15383
  2049
lemma sin_cos_npi [simp]: "sin (real (Suc (2 * n)) * pi / 2) = (-1) ^ n"
paulson@15383
  2050
proof -
paulson@15383
  2051
  have "sin ((real n + 1/2) * pi) = cos (real n * pi)"
nipkow@29667
  2052
    by (auto simp add: algebra_simps sin_add)
paulson@15383
  2053
  thus ?thesis
paulson@15383
  2054
    by (simp add: real_of_nat_Suc left_distrib add_divide_distrib 
paulson@15383
  2055
                  mult_commute [of pi])
paulson@15383
  2056
qed
paulson@15077
  2057
paulson@15077
  2058
lemma cos_2npi [simp]: "cos (2 * real (n::nat) * pi) = 1"
paulson@15077
  2059
by (simp add: cos_double mult_assoc power_add [symmetric] numeral_2_eq_2)
paulson@15077
  2060
paulson@15077
  2061
lemma cos_3over2_pi [simp]: "cos (3 / 2 * pi) = 0"
huffman@23066
  2062
apply (subgoal_tac "cos (pi + pi/2) = 0", simp)
huffman@23066
  2063
apply (subst cos_add, simp)
paulson@15077
  2064
done
paulson@15077
  2065
paulson@15077
  2066
lemma sin_2npi [simp]: "sin (2 * real (n::nat) * pi) = 0"
paulson@15077
  2067
by (auto simp add: mult_assoc)
paulson@15077
  2068
paulson@15077
  2069
lemma sin_3over2_pi [simp]: "sin (3 / 2 * pi) = - 1"
huffman@23066
  2070
apply (subgoal_tac "sin (pi + pi/2) = - 1", simp)
huffman@23066
  2071
apply (subst sin_add, simp)
paulson@15077
  2072
done
paulson@15077
  2073
paulson@15077
  2074
(*NEEDED??*)
paulson@15229
  2075
lemma [simp]:
paulson@15229
  2076
     "cos(x + 1 / 2 * real(Suc m) * pi) = -sin (x + 1 / 2 * real m * pi)"
paulson@15077
  2077
apply (simp only: cos_add sin_add real_of_nat_Suc right_distrib left_distrib minus_mult_right, auto)
paulson@15077
  2078
done
paulson@15077
  2079
paulson@15077
  2080
(*NEEDED??*)
paulson@15077
  2081
lemma [simp]: "cos (x + real(Suc m) * pi / 2) = -sin (x + real m * pi / 2)"
paulson@15229
  2082
by (simp only: cos_add sin_add real_of_nat_Suc left_distrib add_divide_distrib, auto)
paulson@15077
  2083
paulson@15077
  2084
lemma cos_pi_eq_zero [simp]: "cos (pi * real (Suc (2 * m)) / 2) = 0"
paulson@15229
  2085
by (simp only: cos_add sin_add real_of_nat_Suc left_distrib right_distrib add_divide_distrib, auto)
paulson@15077
  2086
paulson@15077
  2087
lemma DERIV_cos_add [simp]: "DERIV (%x. cos (x + k)) xa :> - sin (xa + k)"
paulson@15077
  2088
apply (rule lemma_DERIV_subst)
paulson@15077
  2089
apply (rule_tac f = cos and g = "%x. x + k" in DERIV_chain2)
paulson@15077
  2090
apply (best intro!: DERIV_intros intro: DERIV_chain2)+
paulson@15077
  2091
apply (simp (no_asm))
paulson@15077
  2092
done
paulson@15077
  2093
paulson@15081
  2094
lemma sin_zero_abs_cos_one: "sin x = 0 ==> \<bar>cos x\<bar> = 1"
nipkow@15539
  2095
by (auto simp add: sin_zero_iff even_mult_two_ex)
paulson@15077
  2096
paulson@15077
  2097
lemma cos_one_sin_zero: "cos x = 1 ==> sin x = 0"
paulson@15077
  2098
by (cut_tac x = x in sin_cos_squared_add3, auto)
paulson@15077
  2099
paulson@15077
  2100
huffman@22978
  2101
subsection {* Existence of Polar Coordinates *}
paulson@15077
  2102
huffman@22978
  2103
lemma cos_x_y_le_one: "\<bar>x / sqrt (x\<twosuperior> + y\<twosuperior>)\<bar> \<le> 1"
huffman@22978
  2104
apply (rule power2_le_imp_le [OF _ zero_le_one])
huffman@22978
  2105
apply (simp add: abs_divide power_divide divide_le_eq not_sum_power2_lt_zero)
paulson@15077
  2106
done
paulson@15077
  2107
huffman@22978
  2108
lemma cos_arccos_abs: "\<bar>y\<bar> \<le> 1 \<Longrightarrow> cos (arccos y) = y"
huffman@22978
  2109
by (simp add: abs_le_iff)
paulson@15077
  2110
huffman@23045
  2111
lemma sin_arccos_abs: "\<bar>y\<bar> \<le> 1 \<Longrightarrow> sin (arccos y) = sqrt (1 - y\<twosuperior>)"
huffman@23045
  2112
by (simp add: sin_arccos abs_le_iff)
paulson@15077
  2113
huffman@22978
  2114
lemmas cos_arccos_lemma1 = cos_arccos_abs [OF cos_x_y_le_one]
paulson@15228
  2115
huffman@23045
  2116
lemmas sin_arccos_lemma1 = sin_arccos_abs [OF cos_x_y_le_one]
paulson@15077
  2117
paulson@15229
  2118
lemma polar_ex1:
huffman@22978
  2119
     "0 < y ==> \<exists>r a. x = r * cos a & y = r * sin a"
paulson@15229
  2120
apply (rule_tac x = "sqrt (x\<twosuperior> + y\<twosuperior>)" in exI)
huffman@22978
  2121
apply (rule_tac x = "arccos (x / sqrt (x\<twosuperior> + y\<twosuperior>))" in exI)
huffman@22978
  2122
apply (simp add: cos_arccos_lemma1)
huffman@23045
  2123
apply (simp add: sin_arccos_lemma1)
huffman@23045
  2124
apply (simp add: power_divide)
huffman@23045
  2125
apply (simp add: real_sqrt_mult [symmetric])
huffman@23045
  2126
apply (simp add: right_diff_distrib)
paulson@15077
  2127
done
paulson@15077
  2128
paulson@15229
  2129
lemma polar_ex2:
huffman@22978
  2130
     "y < 0 ==> \<exists>r a. x = r * cos a & y = r * sin a"
huffman@22978
  2131
apply (insert polar_ex1 [where x=x and y="-y"], simp, clarify)
paulson@15077
  2132
apply (rule_tac x = r in exI)
huffman@22978
  2133
apply (rule_tac x = "-a" in exI, simp)
paulson@15077
  2134
done
paulson@15077
  2135
paulson@15077
  2136
lemma polar_Ex: "\<exists>r a. x = r * cos a & y = r * sin a"
huffman@22978
  2137
apply (rule_tac x=0 and y=y in linorder_cases)
huffman@22978
  2138
apply (erule polar_ex1)
huffman@22978
  2139
apply (rule_tac x=x in exI, rule_tac x=0 in exI, simp)
huffman@22978
  2140
apply (erule polar_ex2)
paulson@15077
  2141
done
paulson@15077
  2142
paulson@12196
  2143
end