diff options
author | desmettr <desmettr@85f007b7-540e-0410-9357-904b9bb8a0f7> | 2003-01-21 16:06:20 +0000 |
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committer | desmettr <desmettr@85f007b7-540e-0410-9357-904b9bb8a0f7> | 2003-01-21 16:06:20 +0000 |
commit | 92bac4d9048a189113469516744db34af82cc421 (patch) | |
tree | 70f19f936cc3b630a9bb6d08223347bfbe756eb5 /theories/Reals/AltSeries.v | |
parent | 785771ebd3f16778712828bee0aba79bb01e6525 (diff) |
Renommage dans AltSeries.v
git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@3558 85f007b7-540e-0410-9357-904b9bb8a0f7
Diffstat (limited to 'theories/Reals/AltSeries.v')
-rw-r--r-- | theories/Reals/AltSeries.v | 41 |
1 files changed, 19 insertions, 22 deletions
diff --git a/theories/Reals/AltSeries.v b/theories/Reals/AltSeries.v index c5c4ec38a..c5e1e0ba5 100644 --- a/theories/Reals/AltSeries.v +++ b/theories/Reals/AltSeries.v @@ -17,10 +17,9 @@ Require Max. (**********) Definition tg_alt [Un:nat->R] : nat->R := [i:nat]``(pow (-1) i)*(Un i)``. -Definition positivity_sui [Un:nat->R] : Prop := (n:nat)``0<=(Un n)``. +Definition positivity_seq [Un:nat->R] : Prop := (n:nat)``0<=(Un n)``. -(* Croissance des sommes partielles impaires *) -Lemma CV_ALT_step1 : (Un:nat->R) (Un_decreasing Un) -> (Un_growing [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N)))). +Lemma CV_ALT_step0 : (Un:nat->R) (Un_decreasing Un) -> (Un_growing [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N)))). Intros; Unfold Un_growing; Intro. Cut (mult (S (S O)) (S n)) = (S (S (mult (2) n))). Intro; Rewrite H0. @@ -35,8 +34,7 @@ Cut (n:nat) (S n)=(plus n (1)); [Intro | Intro; Ring]. Rewrite (H0 n); Rewrite (H0 (S (mult (2) n))); Rewrite (H0 (mult (2) n)); Ring. Qed. -(* Décroissance des sommes partielles paires *) -Lemma CV_ALT_step1_bis : (Un:nat->R) (Un_decreasing Un) -> (Un_decreasing [N:nat](sum_f_R0 (tg_alt Un) (mult (2) N))). +Lemma CV_ALT_step1 : (Un:nat->R) (Un_decreasing Un) -> (Un_decreasing [N:nat](sum_f_R0 (tg_alt Un) (mult (2) N))). Intros; Unfold Un_decreasing; Intro. Cut (mult (S (S O)) (S n)) = (S (S (mult (2) n))). Intro; Rewrite H0; Do 2 Rewrite tech5; Repeat Rewrite Rplus_assoc. @@ -51,7 +49,7 @@ Rewrite (H0 n); Rewrite (H0 (S (mult (2) n))); Rewrite (H0 (mult (2) n)); Ring. Qed. (**********) -Lemma CV_ALT_step2 : (Un:nat->R;N:nat) (Un_decreasing Un) -> (positivity_sui Un) -> (Rle (sum_f_R0 [i:nat](tg_alt Un (S i)) (S (mult (2) N))) R0). +Lemma CV_ALT_step2 : (Un:nat->R;N:nat) (Un_decreasing Un) -> (positivity_seq Un) -> (Rle (sum_f_R0 [i:nat](tg_alt Un (S i)) (S (mult (2) N))) R0). Intros; Induction N. Simpl; Unfold tg_alt; Simpl; Rewrite Rmult_1r. Replace ``-1* -1*(Un (S (S O)))`` with (Un (S (S O))); [Idtac | Ring]. @@ -75,7 +73,7 @@ Apply INR_eq; Repeat Rewrite S_INR; Do 2 Rewrite mult_INR; Repeat Rewrite S_INR; Qed. (* A more general inequality *) -Lemma CV_ALT_step3 : (Un:nat->R;N:nat) (Un_decreasing Un) -> (positivity_sui Un) -> (Rle (sum_f_R0 [i:nat](tg_alt Un (S i)) N) R0). +Lemma CV_ALT_step3 : (Un:nat->R;N:nat) (Un_decreasing Un) -> (positivity_seq Un) -> (Rle (sum_f_R0 [i:nat](tg_alt Un (S i)) N) R0). Intros; Induction N. Simpl; Unfold tg_alt; Simpl; Rewrite Rmult_1r. Apply Rle_anti_compatibility with (Un (S O)). @@ -99,7 +97,7 @@ Apply CV_ALT_step2; Assumption. Qed. (**********) -Lemma CV_ALT_step4 : (Un:nat->R) (Un_decreasing Un) -> (positivity_sui Un) -> (majoree [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N)))). +Lemma CV_ALT_step4 : (Un:nat->R) (Un_decreasing Un) -> (positivity_seq Un) -> (majoree [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N)))). Intros; Unfold majoree; Unfold bound. Exists ``(Un O)``. Unfold is_upper_bound; Intros; Elim H1; Intros. @@ -112,10 +110,10 @@ Unfold tg_alt; Simpl; Ring. Apply lt_O_Sn. Qed. -(* Ceci donne quasiment le résultat sur la convergence des séries alternées *) -Lemma CV_ALT : (Un:nat->R) (Un_decreasing Un) -> (positivity_sui Un) -> (Un_cv Un R0) -> (sigTT R [l:R](Un_cv [N:nat](sum_f_R0 (tg_alt Un) N) l)). +(* This lemma gives an interesting result about alternated series *) +Lemma CV_ALT : (Un:nat->R) (Un_decreasing Un) -> (positivity_seq Un) -> (Un_cv Un R0) -> (sigTT R [l:R](Un_cv [N:nat](sum_f_R0 (tg_alt Un) N) l)). Intros. -Assert H2 := (CV_ALT_step1 ? H). +Assert H2 := (CV_ALT_step0 ? H). Assert H3 := (CV_ALT_step4 ? H H0). Assert X := (growing_cv ? H2 H3). Elim X; Intros. @@ -161,28 +159,27 @@ Assumption. Qed. (************************************************) -(* Théorème de convergence des séries alternées *) +(* Convergence of alternated series *) (* *) -(* Applications: PI, cos, sin... *) +(* Applications: PI, cos, sin *) (************************************************) -Theorem Series_Alternees : (Un:nat->R) (Un_decreasing Un) -> (Un_cv Un R0) -> (sigTT R [l:R](Un_cv [N:nat](sum_f_R0 (tg_alt Un) N) l)). +Theorem alternated_series : (Un:nat->R) (Un_decreasing Un) -> (Un_cv Un R0) -> (sigTT R [l:R](Un_cv [N:nat](sum_f_R0 (tg_alt Un) N) l)). Intros; Apply CV_ALT. Assumption. -Unfold positivity_sui; Apply decreasing_ineq; Assumption. +Unfold positivity_seq; Apply decreasing_ineq; Assumption. Assumption. Qed. -(* Encadrement de la limite par les sommes partielles *) -Theorem sommes_partielles_ineq : (Un:nat->R;l:R;N:nat) (Un_decreasing Un) -> (Un_cv Un R0) -> (Un_cv [N:nat](sum_f_R0 (tg_alt Un) N) l) -> ``(sum_f_R0 (tg_alt Un) (S (mult (S (S O)) N)))<=l<=(sum_f_R0 (tg_alt Un) (mult (S (S O)) N))``. +Theorem alternated_series_ineq : (Un:nat->R;l:R;N:nat) (Un_decreasing Un) -> (Un_cv Un R0) -> (Un_cv [N:nat](sum_f_R0 (tg_alt Un) N) l) -> ``(sum_f_R0 (tg_alt Un) (S (mult (S (S O)) N)))<=l<=(sum_f_R0 (tg_alt Un) (mult (S (S O)) N))``. Intros. Cut (Un_cv [N:nat](sum_f_R0 (tg_alt Un) (mult (2) N)) l). Cut (Un_cv [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N))) l). Intros; Split. Apply (growing_ineq [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N)))). -Apply CV_ALT_step1; Assumption. +Apply CV_ALT_step0; Assumption. Assumption. Apply (decreasing_ineq [N:nat](sum_f_R0 (tg_alt Un) (mult (2) N))). -Apply CV_ALT_step1_bis; Assumption. +Apply CV_ALT_step1; Assumption. Assumption. Unfold Un_cv; Unfold R_dist; Unfold Un_cv in H1; Unfold R_dist in H1; Intros. Elim (H1 eps H2); Intros. @@ -209,7 +206,7 @@ Assumption. Qed. (************************************) -(* Application : construction de PI *) +(* Application : construction of PI *) (************************************) Definition PI_tg := [n:nat]``/(INR (plus (mult (S (S O)) n) (S O)))``. @@ -328,7 +325,7 @@ Elim H1; Intros; Assumption. Qed. Lemma exist_PI : (sigTT R [l:R](Un_cv [N:nat](sum_f_R0 (tg_alt PI_tg) N) l)). -Apply Series_Alternees. +Apply alternated_series. Apply PI_tg_decreasing. Apply PI_tg_cv. Qed. @@ -338,7 +335,7 @@ Definition PI : R := (Rmult ``4`` (Cases exist_PI of (existTT a b) => a end)). (* We can get an approximation of PI with the following inequality *) Lemma PI_ineq : (N:nat) ``(sum_f_R0 (tg_alt PI_tg) (S (mult (S (S O)) N)))<=PI/4<=(sum_f_R0 (tg_alt PI_tg) (mult (S (S O)) N))``. -Intro; Apply sommes_partielles_ineq. +Intro; Apply alternated_series_ineq. Apply PI_tg_decreasing. Apply PI_tg_cv. Unfold PI; Case exist_PI; Intro. |