diff options
Diffstat (limited to 'theories/Reals/Rtrigo_alt.v')
| -rw-r--r-- | theories/Reals/Rtrigo_alt.v | 165 |
1 files changed, 78 insertions, 87 deletions
diff --git a/theories/Reals/Rtrigo_alt.v b/theories/Reals/Rtrigo_alt.v index de984415..23b8e847 100644 --- a/theories/Reals/Rtrigo_alt.v +++ b/theories/Reals/Rtrigo_alt.v @@ -1,18 +1,16 @@ (************************************************************************) (* v * The Coq Proof Assistant / The Coq Development Team *) -(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2011 *) +(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2012 *) (* \VV/ **************************************************************) (* // * This file is distributed under the terms of the *) (* * GNU Lesser General Public License Version 2.1 *) (************************************************************************) -(*i $Id: Rtrigo_alt.v 14641 2011-11-06 11:59:10Z herbelin $ i*) - Require Import Rbase. Require Import Rfunctions. Require Import SeqSeries. Require Import Rtrigo_def. -Open Local Scope R_scope. +Local Open Scope R_scope. (***************************************************************) (** Using series definitions of cos and sin *) @@ -29,7 +27,8 @@ Definition sin_approx (a:R) (n:nat) : R := sum_f_R0 (sin_term a) n. Definition cos_approx (a:R) (n:nat) : R := sum_f_R0 (cos_term a) n. (**********) -Lemma PI_4 : PI <= 4. +(* +Lemma Alt_PI_4 : Alt_PI <= 4. Proof. assert (H0 := PI_ineq 0). elim H0; clear H0; intros _ H0. @@ -39,20 +38,20 @@ Proof. apply Rinv_0_lt_compat; prove_sup0. rewrite <- Rinv_l_sym; [ rewrite Rmult_comm; assumption | discrR ]. Qed. - +*) (**********) -Theorem sin_bound : +Theorem pre_sin_bound : forall (a:R) (n:nat), 0 <= a -> - a <= PI -> sin_approx a (2 * n + 1) <= sin a <= sin_approx a (2 * (n + 1)). + a <= 4 -> sin_approx a (2 * n + 1) <= sin a <= sin_approx a (2 * (n + 1)). Proof. intros; case (Req_dec a 0); intro Hyp_a. - rewrite Hyp_a; rewrite sin_0; split; right; unfold sin_approx in |- *; - apply sum_eq_R0 || (symmetry in |- *; apply sum_eq_R0); - intros; unfold sin_term in |- *; rewrite pow_add; - simpl in |- *; unfold Rdiv in |- *; rewrite Rmult_0_l; + rewrite Hyp_a; rewrite sin_0; split; right; unfold sin_approx; + apply sum_eq_R0 || (symmetry ; apply sum_eq_R0); + intros; unfold sin_term; rewrite pow_add; + simpl; unfold Rdiv; rewrite Rmult_0_l; ring. - unfold sin_approx in |- *; cut (0 < a). + unfold sin_approx; cut (0 < a). intro Hyp_a_pos. rewrite (decomp_sum (sin_term a) (2 * n + 1)). rewrite (decomp_sum (sin_term a) (2 * (n + 1))). @@ -77,22 +76,22 @@ Proof. - sum_f_R0 (tg_alt Un) (S (2 * n))). intro; apply H2. apply alternated_series_ineq. - unfold Un_decreasing, Un in |- *; intro; + unfold Un_decreasing, Un; intro; cut ((2 * S (S n0) + 1)%nat = S (S (2 * S n0 + 1))). intro; rewrite H3. replace (a ^ S (S (2 * S n0 + 1))) with (a ^ (2 * S n0 + 1) * (a * a)). - unfold Rdiv in |- *; rewrite Rmult_assoc; apply Rmult_le_compat_l. + unfold Rdiv; rewrite Rmult_assoc; apply Rmult_le_compat_l. left; apply pow_lt; assumption. apply Rmult_le_reg_l with (INR (fact (S (S (2 * S n0 + 1))))). - rewrite <- H3; apply lt_INR_0; apply neq_O_lt; red in |- *; intro; - assert (H5 := sym_eq H4); elim (fact_neq_0 _ H5). + rewrite <- H3; apply lt_INR_0; apply neq_O_lt; red; intro; + assert (H5 := eq_sym H4); elim (fact_neq_0 _ H5). rewrite <- H3; rewrite (Rmult_comm (INR (fact (2 * S (S n0) + 1)))); rewrite Rmult_assoc; rewrite <- Rinv_l_sym. rewrite Rmult_1_r; rewrite H3; do 2 rewrite fact_simpl; do 2 rewrite mult_INR; repeat rewrite Rmult_assoc; rewrite <- Rinv_r_sym. rewrite Rmult_1_r. do 2 rewrite S_INR; rewrite plus_INR; rewrite mult_INR; repeat rewrite S_INR; - simpl in |- *; + simpl; replace (((0 + 1 + 1) * (INR n0 + 1) + (0 + 1) + 1 + 1) * ((0 + 1 + 1) * (INR n0 + 1) + (0 + 1) + 1)) with @@ -102,12 +101,12 @@ Proof. replace 16 with (Rsqr 4); [ idtac | ring_Rsqr ]. replace (a * a) with (Rsqr a); [ idtac | reflexivity ]. apply Rsqr_incr_1. - apply Rle_trans with PI; [ assumption | apply PI_4 ]. + assumption. assumption. left; prove_sup0. rewrite <- (Rplus_0_r 16); replace 20 with (16 + 4); [ apply Rplus_le_compat_l; left; prove_sup0 | ring ]. - rewrite <- (Rplus_comm 20); pattern 20 at 1 in |- *; rewrite <- Rplus_0_r; + rewrite <- (Rplus_comm 20); pattern 20 at 1; rewrite <- Rplus_0_r; apply Rplus_le_compat_l. apply Rplus_le_le_0_compat. repeat apply Rmult_le_pos. @@ -120,14 +119,14 @@ Proof. replace 0 with (INR 0); [ apply le_INR; apply le_O_n | reflexivity ]. apply INR_fact_neq_0. apply INR_fact_neq_0. - simpl in |- *; ring. + simpl; ring. ring. - assert (H3 := cv_speed_pow_fact a); unfold Un in |- *; unfold Un_cv in H3; - unfold R_dist in H3; unfold Un_cv in |- *; unfold R_dist in |- *; + assert (H3 := cv_speed_pow_fact a); unfold Un; unfold Un_cv in H3; + unfold R_dist in H3; unfold Un_cv; unfold R_dist; intros; elim (H3 eps H4); intros N H5. exists N; intros; apply H5. replace (2 * S n0 + 1)%nat with (S (2 * S n0)). - unfold ge in |- *; apply le_trans with (2 * S n0)%nat. + unfold ge; apply le_trans with (2 * S n0)%nat. apply le_trans with (2 * S N)%nat. apply le_trans with (2 * N)%nat. apply le_n_2n. @@ -138,49 +137,49 @@ Proof. assert (X := exist_sin (Rsqr a)); elim X; intros. cut (x = sin a / a). intro; rewrite H3 in p; unfold sin_in in p; unfold infinite_sum in p; - unfold R_dist in p; unfold Un_cv in |- *; unfold R_dist in |- *; + unfold R_dist in p; unfold Un_cv; unfold R_dist; intros. cut (0 < eps / Rabs a). intro; elim (p _ H5); intros N H6. exists N; intros. replace (sum_f_R0 (tg_alt Un) n0) with (a * (1 - sum_f_R0 (fun i:nat => sin_n i * Rsqr a ^ i) (S n0))). - unfold Rminus in |- *; rewrite Rmult_plus_distr_l; rewrite Rmult_1_r; + unfold Rminus; rewrite Rmult_plus_distr_l; rewrite Rmult_1_r; rewrite Ropp_plus_distr; rewrite Ropp_involutive; repeat rewrite Rplus_assoc; rewrite (Rplus_comm a); rewrite (Rplus_comm (- a)); repeat rewrite Rplus_assoc; rewrite Rplus_opp_l; rewrite Rplus_0_r; apply Rmult_lt_reg_l with (/ Rabs a). apply Rinv_0_lt_compat; apply Rabs_pos_lt; assumption. - pattern (/ Rabs a) at 1 in |- *; rewrite <- (Rabs_Rinv a Hyp_a). + pattern (/ Rabs a) at 1; rewrite <- (Rabs_Rinv a Hyp_a). rewrite <- Rabs_mult; rewrite Rmult_plus_distr_l; rewrite <- Rmult_assoc; rewrite <- Rinv_l_sym; [ rewrite Rmult_1_l | assumption ]; rewrite (Rmult_comm (/ a)); rewrite (Rmult_comm (/ Rabs a)); rewrite <- Rabs_Ropp; rewrite Ropp_plus_distr; rewrite Ropp_involutive; - unfold Rminus, Rdiv in H6; apply H6; unfold ge in |- *; + unfold Rminus, Rdiv in H6; apply H6; unfold ge; apply le_trans with n0; [ exact H7 | apply le_n_Sn ]. rewrite (decomp_sum (fun i:nat => sin_n i * Rsqr a ^ i) (S n0)). replace (sin_n 0) with 1. - simpl in |- *; rewrite Rmult_1_r; unfold Rminus in |- *; + simpl; rewrite Rmult_1_r; unfold Rminus; rewrite Ropp_plus_distr; rewrite <- Rplus_assoc; rewrite Rplus_opp_r; rewrite Rplus_0_l; rewrite Ropp_mult_distr_r_reverse; rewrite <- Ropp_mult_distr_l_reverse; rewrite scal_sum; apply sum_eq. - intros; unfold sin_n, Un, tg_alt in |- *; + intros; unfold sin_n, Un, tg_alt; replace ((-1) ^ S i) with (- (-1) ^ i). replace (a ^ (2 * S i + 1)) with (Rsqr a * Rsqr a ^ i * a). - unfold Rdiv in |- *; ring. - rewrite pow_add; rewrite pow_Rsqr; simpl in |- *; ring. - simpl in |- *; ring. - unfold sin_n in |- *; unfold Rdiv in |- *; simpl in |- *; rewrite Rinv_1; + unfold Rdiv; ring. + rewrite pow_add; rewrite pow_Rsqr; simpl; ring. + simpl; ring. + unfold sin_n; unfold Rdiv; simpl; rewrite Rinv_1; rewrite Rmult_1_r; reflexivity. apply lt_O_Sn. - unfold Rdiv in |- *; apply Rmult_lt_0_compat. + unfold Rdiv; apply Rmult_lt_0_compat. assumption. apply Rinv_0_lt_compat; apply Rabs_pos_lt; assumption. - unfold sin in |- *; case (exist_sin (Rsqr a)). + unfold sin; case (exist_sin (Rsqr a)). intros; cut (x = x0). - intro; rewrite H3; unfold Rdiv in |- *. - symmetry in |- *; apply Rinv_r_simpl_m; assumption. + intro; rewrite H3; unfold Rdiv. + symmetry ; apply Rinv_r_simpl_m; assumption. unfold sin_in in p; unfold sin_in in s; eapply uniqueness_sum. apply p. apply s. @@ -189,16 +188,16 @@ Proof. split; apply Ropp_le_contravar; assumption. replace (- sum_f_R0 (tg_alt Un) (S (2 * n))) with (-1 * sum_f_R0 (tg_alt Un) (S (2 * n))); [ rewrite scal_sum | ring ]. - apply sum_eq; intros; unfold sin_term, Un, tg_alt in |- *; + apply sum_eq; intros; unfold sin_term, Un, tg_alt; replace ((-1) ^ S i) with (-1 * (-1) ^ i). - unfold Rdiv in |- *; ring. + unfold Rdiv; ring. reflexivity. replace (- sum_f_R0 (tg_alt Un) (2 * n)) with (-1 * sum_f_R0 (tg_alt Un) (2 * n)); [ rewrite scal_sum | ring ]. apply sum_eq; intros. - unfold sin_term, Un, tg_alt in |- *; + unfold sin_term, Un, tg_alt; replace ((-1) ^ S i) with (-1 * (-1) ^ i). - unfold Rdiv in |- *; ring. + unfold Rdiv; ring. reflexivity. replace (2 * (n + 1))%nat with (S (S (2 * n))). reflexivity. @@ -214,7 +213,7 @@ Proof. apply Rplus_le_reg_l with (- a). rewrite <- Rplus_assoc; rewrite Rplus_opp_l; rewrite Rplus_0_l; rewrite (Rplus_comm (- a)); apply H3. - unfold sin_term in |- *; simpl in |- *; unfold Rdiv in |- *; rewrite Rinv_1; + unfold sin_term; simpl; unfold Rdiv; rewrite Rinv_1; ring. replace (2 * (n + 1))%nat with (S (S (2 * n))). apply lt_O_Sn. @@ -222,27 +221,26 @@ Proof. replace (2 * n + 1)%nat with (S (2 * n)). apply lt_O_Sn. ring. - inversion H; [ assumption | elim Hyp_a; symmetry in |- *; assumption ]. + inversion H; [ assumption | elim Hyp_a; symmetry ; assumption ]. Qed. (**********) -Lemma cos_bound : +Lemma pre_cos_bound : forall (a:R) (n:nat), - - PI / 2 <= a -> - a <= PI / 2 -> + - 2 <= a -> a <= 2 -> cos_approx a (2 * n + 1) <= cos a <= cos_approx a (2 * (n + 1)). Proof. cut ((forall (a:R) (n:nat), 0 <= a -> - a <= PI / 2 -> + a <= 2 -> cos_approx a (2 * n + 1) <= cos a <= cos_approx a (2 * (n + 1))) -> forall (a:R) (n:nat), - - PI / 2 <= a -> - a <= PI / 2 -> + - 2 <= a -> + a <= 2 -> cos_approx a (2 * n + 1) <= cos a <= cos_approx a (2 * (n + 1))). intros H a n; apply H. - intros; unfold cos_approx in |- *. + intros; unfold cos_approx. rewrite (decomp_sum (cos_term a0) (2 * n0 + 1)). rewrite (decomp_sum (cos_term a0) (2 * (n0 + 1))). replace (cos_term a0 0) with 1. @@ -268,21 +266,21 @@ Proof. - sum_f_R0 (tg_alt Un) (S (2 * n0))). intro; apply H3. apply alternated_series_ineq. - unfold Un_decreasing in |- *; intro; unfold Un in |- *. + unfold Un_decreasing; intro; unfold Un. cut ((2 * S (S n1))%nat = S (S (2 * S n1))). intro; rewrite H4; replace (a0 ^ S (S (2 * S n1))) with (a0 ^ (2 * S n1) * (a0 * a0)). - unfold Rdiv in |- *; rewrite Rmult_assoc; apply Rmult_le_compat_l. + unfold Rdiv; rewrite Rmult_assoc; apply Rmult_le_compat_l. apply pow_le; assumption. apply Rmult_le_reg_l with (INR (fact (S (S (2 * S n1))))). - rewrite <- H4; apply lt_INR_0; apply neq_O_lt; red in |- *; intro; - assert (H6 := sym_eq H5); elim (fact_neq_0 _ H6). + rewrite <- H4; apply lt_INR_0; apply neq_O_lt; red; intro; + assert (H6 := eq_sym H5); elim (fact_neq_0 _ H6). rewrite <- H4; rewrite (Rmult_comm (INR (fact (2 * S (S n1))))); rewrite Rmult_assoc; rewrite <- Rinv_l_sym. rewrite Rmult_1_r; rewrite H4; do 2 rewrite fact_simpl; do 2 rewrite mult_INR; repeat rewrite Rmult_assoc; rewrite <- Rinv_r_sym. rewrite Rmult_1_r; do 2 rewrite S_INR; rewrite mult_INR; repeat rewrite S_INR; - simpl in |- *; + simpl; replace (((0 + 1 + 1) * (INR n1 + 1) + 1 + 1) * ((0 + 1 + 1) * (INR n1 + 1) + 1)) with (4 * INR n1 * INR n1 + 14 * INR n1 + 12); [ idtac | ring ]. @@ -291,18 +289,13 @@ Proof. replace 4 with (Rsqr 2); [ idtac | ring_Rsqr ]. replace (a0 * a0) with (Rsqr a0); [ idtac | reflexivity ]. apply Rsqr_incr_1. - apply Rle_trans with (PI / 2). assumption. - unfold Rdiv in |- *; apply Rmult_le_reg_l with 2. - prove_sup0. - rewrite <- Rmult_assoc; rewrite Rinv_r_simpl_m. - replace 4 with 4; [ apply PI_4 | ring ]. discrR. assumption. left; prove_sup0. - pattern 4 at 1 in |- *; rewrite <- Rplus_0_r; replace 12 with (4 + 8); + pattern 4 at 1; rewrite <- Rplus_0_r; replace 12 with (4 + 8); [ apply Rplus_le_compat_l; left; prove_sup0 | ring ]. - rewrite <- (Rplus_comm 12); pattern 12 at 1 in |- *; rewrite <- Rplus_0_r; + rewrite <- (Rplus_comm 12); pattern 12 at 1; rewrite <- Rplus_0_r; apply Rplus_le_compat_l. apply Rplus_le_le_0_compat. repeat apply Rmult_le_pos. @@ -315,12 +308,12 @@ Proof. replace 0 with (INR 0); [ apply le_INR; apply le_O_n | reflexivity ]. apply INR_fact_neq_0. apply INR_fact_neq_0. - simpl in |- *; ring. + simpl; ring. ring. - assert (H4 := cv_speed_pow_fact a0); unfold Un in |- *; unfold Un_cv in H4; - unfold R_dist in H4; unfold Un_cv in |- *; unfold R_dist in |- *; + assert (H4 := cv_speed_pow_fact a0); unfold Un; unfold Un_cv in H4; + unfold R_dist in H4; unfold Un_cv; unfold R_dist; intros; elim (H4 eps H5); intros N H6; exists N; intros. - apply H6; unfold ge in |- *; apply le_trans with (2 * S N)%nat. + apply H6; unfold ge; apply le_trans with (2 * S N)%nat. apply le_trans with (2 * N)%nat. apply le_n_2n. apply (fun m n p:nat => mult_le_compat_l p n m); apply le_n_Sn. @@ -328,40 +321,40 @@ Proof. assert (X := exist_cos (Rsqr a0)); elim X; intros. cut (x = cos a0). intro; rewrite H4 in p; unfold cos_in in p; unfold infinite_sum in p; - unfold R_dist in p; unfold Un_cv in |- *; unfold R_dist in |- *; + unfold R_dist in p; unfold Un_cv; unfold R_dist; intros. elim (p _ H5); intros N H6. exists N; intros. replace (sum_f_R0 (tg_alt Un) n1) with (1 - sum_f_R0 (fun i:nat => cos_n i * Rsqr a0 ^ i) (S n1)). - unfold Rminus in |- *; rewrite Ropp_plus_distr; rewrite Ropp_involutive; + unfold Rminus; rewrite Ropp_plus_distr; rewrite Ropp_involutive; repeat rewrite Rplus_assoc; rewrite (Rplus_comm 1); rewrite (Rplus_comm (-1)); repeat rewrite Rplus_assoc; rewrite Rplus_opp_l; rewrite Rplus_0_r; rewrite <- Rabs_Ropp; rewrite Ropp_plus_distr; rewrite Ropp_involutive; unfold Rminus in H6; apply H6. - unfold ge in |- *; apply le_trans with n1. + unfold ge; apply le_trans with n1. exact H7. apply le_n_Sn. rewrite (decomp_sum (fun i:nat => cos_n i * Rsqr a0 ^ i) (S n1)). replace (cos_n 0) with 1. - simpl in |- *; rewrite Rmult_1_r; unfold Rminus in |- *; + simpl; rewrite Rmult_1_r; unfold Rminus; rewrite Ropp_plus_distr; rewrite <- Rplus_assoc; rewrite Rplus_opp_r; rewrite Rplus_0_l; replace (- sum_f_R0 (fun i:nat => cos_n (S i) * (Rsqr a0 * Rsqr a0 ^ i)) n1) with (-1 * sum_f_R0 (fun i:nat => cos_n (S i) * (Rsqr a0 * Rsqr a0 ^ i)) n1); [ idtac | ring ]; rewrite scal_sum; apply sum_eq; - intros; unfold cos_n, Un, tg_alt in |- *. + intros; unfold cos_n, Un, tg_alt. replace ((-1) ^ S i) with (- (-1) ^ i). replace (a0 ^ (2 * S i)) with (Rsqr a0 * Rsqr a0 ^ i). - unfold Rdiv in |- *; ring. + unfold Rdiv; ring. rewrite pow_Rsqr; reflexivity. - simpl in |- *; ring. - unfold cos_n in |- *; unfold Rdiv in |- *; simpl in |- *; rewrite Rinv_1; + simpl; ring. + unfold cos_n; unfold Rdiv; simpl; rewrite Rinv_1; rewrite Rmult_1_r; reflexivity. apply lt_O_Sn. - unfold cos in |- *; case (exist_cos (Rsqr a0)); intros; unfold cos_in in p; + unfold cos; case (exist_cos (Rsqr a0)); intros; unfold cos_in in p; unfold cos_in in c; eapply uniqueness_sum. apply p. apply c. @@ -370,15 +363,15 @@ Proof. split; apply Ropp_le_contravar; assumption. replace (- sum_f_R0 (tg_alt Un) (S (2 * n0))) with (-1 * sum_f_R0 (tg_alt Un) (S (2 * n0))); [ rewrite scal_sum | ring ]. - apply sum_eq; intros; unfold cos_term, Un, tg_alt in |- *; + apply sum_eq; intros; unfold cos_term, Un, tg_alt; replace ((-1) ^ S i) with (-1 * (-1) ^ i). - unfold Rdiv in |- *; ring. + unfold Rdiv; ring. reflexivity. replace (- sum_f_R0 (tg_alt Un) (2 * n0)) with (-1 * sum_f_R0 (tg_alt Un) (2 * n0)); [ rewrite scal_sum | ring ]; - apply sum_eq; intros; unfold cos_term, Un, tg_alt in |- *; + apply sum_eq; intros; unfold cos_term, Un, tg_alt; replace ((-1) ^ S i) with (-1 * (-1) ^ i). - unfold Rdiv in |- *; ring. + unfold Rdiv; ring. reflexivity. replace (2 * (n0 + 1))%nat with (S (S (2 * n0))). reflexivity. @@ -393,7 +386,7 @@ Proof. apply Rplus_le_reg_l with (-1). rewrite <- Rplus_assoc; rewrite Rplus_opp_l; rewrite Rplus_0_l; rewrite (Rplus_comm (-1)); apply H4. - unfold cos_term in |- *; simpl in |- *; unfold Rdiv in |- *; rewrite Rinv_1; + unfold cos_term; simpl; unfold Rdiv; rewrite Rinv_1; ring. replace (2 * (n0 + 1))%nat with (S (S (2 * n0))). apply lt_O_Sn. @@ -409,11 +402,9 @@ Proof. intro; cut (forall (x:R) (n:nat), cos_approx x n = cos_approx (- x) n). intro; rewrite H3; rewrite (H3 a (2 * (n + 1))%nat); rewrite cos_sym; apply H. left; assumption. - rewrite <- (Ropp_involutive (PI / 2)); apply Ropp_le_contravar; - unfold Rdiv in |- *; unfold Rdiv in H0; rewrite <- Ropp_mult_distr_l_reverse; - exact H0. - intros; unfold cos_approx in |- *; apply sum_eq; intros; - unfold cos_term in |- *; do 2 rewrite pow_Rsqr; rewrite Rsqr_neg; - unfold Rdiv in |- *; reflexivity. + rewrite <- (Ropp_involutive 2); apply Ropp_le_contravar; exact H0. + intros; unfold cos_approx; apply sum_eq; intros; + unfold cos_term; do 2 rewrite pow_Rsqr; rewrite Rsqr_neg; + unfold Rdiv; reflexivity. apply Ropp_0_gt_lt_contravar; assumption. Qed. |