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(************************************************************************)
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(* v * The Coq Proof Assistant / The Coq Development Team *)
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(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
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(* \VV/ **************************************************************)
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(* // * This file is distributed under the terms of the *)
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(* * GNU Lesser General Public License Version 2.1 *)
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(************************************************************************)
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(*i $Id: Rtrigo_fun.v 10710 2008-03-23 09:24:09Z herbelin $ i*)
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Require Import Rfunctions.
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Require Import SeqSeries.
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Open Local Scope R_scope.
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(*****************************************************************)
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(** To define transcendental functions *)
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(** and exponential function *)
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(*****************************************************************)
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Un_cv (fun n:nat => Rabs (/ INR (fact (S n)) * / / INR (fact n))) 0.
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unfold Un_cv in |- *; intros; elim (Rgt_dec eps 1); intro.
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split with 0%nat; intros; rewrite (simpl_fact n); unfold R_dist in |- *;
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rewrite (Rminus_0_r (Rabs (/ INR (S n))));
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rewrite (Rabs_Rabsolu (/ INR (S n))); cut (/ INR (S n) > 0).
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intro; rewrite (Rabs_pos_eq (/ INR (S n))).
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intro; generalize (Rlt_le_trans (/ eps - 1) 0 (INR n) H2 (pos_INR n));
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clear H2; intro; unfold Rminus in H2;
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generalize (Rplus_lt_compat_l 1 (/ eps + -1) (INR n) H2);
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replace (1 + (/ eps + -1)) with (/ eps); [ clear H2; intro | ring ].
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rewrite (Rplus_comm 1 (INR n)) in H2; rewrite <- (S_INR n) in H2;
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generalize (Rmult_gt_0_compat (/ INR (S n)) eps H1 H);
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intro; unfold Rgt in H3;
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generalize (Rmult_lt_compat_l (/ INR (S n) * eps) (/ eps) (INR (S n)) H3 H2);
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intro; rewrite (Rmult_assoc (/ INR (S n)) eps (/ eps)) in H4;
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rewrite (Rinv_r eps (Rlt_dichotomy_converse eps 0 (or_intror (eps < 0) H)))
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in H4; rewrite (let (H1, H2) := Rmult_ne (/ INR (S n)) in H1) in H4;
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rewrite (Rmult_comm (/ INR (S n))) in H4;
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rewrite (Rmult_assoc eps (/ INR (S n)) (INR (S n))) in H4;
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rewrite (Rinv_l (INR (S n)) (not_O_INR (S n) (sym_not_equal (O_S n)))) in H4;
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rewrite (let (H1, H2) := Rmult_ne eps in H1) in H4;
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apply Rlt_minus; unfold Rgt in a; rewrite <- Rinv_1;
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apply (Rinv_lt_contravar 1 eps); auto;
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rewrite (let (H1, H2) := Rmult_ne eps in H2); unfold Rgt in H;
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unfold Rgt in H1; apply Rlt_le; assumption.
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unfold Rgt in |- *; apply Rinv_0_lt_compat; apply lt_INR_0; apply lt_O_Sn.
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cut (0 <= up (/ eps - 1))%Z.
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intro; elim (IZN (up (/ eps - 1)) H0); intros; split with x; intros;
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rewrite (simpl_fact n); unfold R_dist in |- *;
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rewrite (Rminus_0_r (Rabs (/ INR (S n))));
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rewrite (Rabs_Rabsolu (/ INR (S n))); cut (/ INR (S n) > 0).
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intro; rewrite (Rabs_pos_eq (/ INR (S n))).
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cut (/ eps - 1 < INR x).
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(Rlt_le_trans (/ eps - 1) (INR x) (INR n) H4
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clear H4; intro; unfold Rminus in H4;
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generalize (Rplus_lt_compat_l 1 (/ eps + -1) (INR n) H4);
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replace (1 + (/ eps + -1)) with (/ eps); [ clear H4; intro | ring ].
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rewrite (Rplus_comm 1 (INR n)) in H4; rewrite <- (S_INR n) in H4;
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generalize (Rmult_gt_0_compat (/ INR (S n)) eps H3 H);
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intro; unfold Rgt in H5;
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generalize (Rmult_lt_compat_l (/ INR (S n) * eps) (/ eps) (INR (S n)) H5 H4);
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intro; rewrite (Rmult_assoc (/ INR (S n)) eps (/ eps)) in H6;
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rewrite (Rinv_r eps (Rlt_dichotomy_converse eps 0 (or_intror (eps < 0) H)))
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in H6; rewrite (let (H1, H2) := Rmult_ne (/ INR (S n)) in H1) in H6;
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rewrite (Rmult_comm (/ INR (S n))) in H6;
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rewrite (Rmult_assoc eps (/ INR (S n)) (INR (S n))) in H6;
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rewrite (Rinv_l (INR (S n)) (not_O_INR (S n) (sym_not_equal (O_S n)))) in H6;
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rewrite (let (H1, H2) := Rmult_ne eps in H1) in H6;
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cut (IZR (up (/ eps - 1)) = IZR (Z_of_nat x));
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[ intro | rewrite H1; trivial ].
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elim (archimed (/ eps - 1)); intros; clear H6; unfold Rgt in H5;
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rewrite H4 in H5; rewrite INR_IZR_INZ; assumption.
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unfold Rgt in H1; apply Rlt_le; assumption.
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unfold Rgt in |- *; apply Rinv_0_lt_compat; apply lt_INR_0; apply lt_O_Sn.
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apply (le_O_IZR (up (/ eps - 1)));
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apply (Rle_trans 0 (/ eps - 1) (IZR (up (/ eps - 1)))).
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generalize (Rnot_gt_le eps 1 b); clear b; unfold Rle in |- *; intro; elim H0;
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left; unfold Rgt in H;
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generalize (Rmult_lt_compat_l (/ eps) eps 1 (Rinv_0_lt_compat eps H) H0);
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(sym_not_eq (Rlt_dichotomy_converse 0 eps (or_introl (0 > eps) H))))
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; rewrite (let (H1, H2) := Rmult_ne (/ eps) in H1);
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intro; fold (/ eps - 1 > 0) in |- *; apply Rgt_minus;
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unfold Rgt in |- *; assumption.
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right; rewrite H0; rewrite Rinv_1; apply sym_eq; apply Rminus_diag_eq; auto.
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elim (archimed (/ eps - 1)); intros; clear H1; unfold Rgt in H0; apply Rlt_le;