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-(************************************************************************)
-(* v * The Coq Proof Assistant / The Coq Development Team *)
-(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
-(* \VV/ **************************************************************)
-(* // * This file is distributed under the terms of the *)
-(* * GNU Lesser General Public License Version 2.1 *)
-(************************************************************************)
-
-(*i $Id: Rderiv.v,v 1.1.2.1 2004/07/16 19:31:34 herbelin Exp $ i*)
-
-(*********************************************************)
-(** Definition of the derivative,continuity *)
-(* *)
-(*********************************************************)
-
-Require Rbase.
-Require Rfunctions.
-Require Rlimit.
-Require Fourier.
-Require Classical_Prop.
-Require Classical_Pred_Type.
-Require Omega.
-V7only [Import R_scope.]. Open Local Scope R_scope.
-
-(*********)
-Definition D_x:(R->Prop)->R->R->Prop:=[D:R->Prop][y:R][x:R]
- (D x)/\(~y==x).
-
-(*********)
-Definition continue_in:(R->R)->(R->Prop)->R->Prop:=
- [f:R->R; D:R->Prop; x0:R](limit1_in f (D_x D x0) (f x0) x0).
-
-(*********)
-Definition D_in:(R->R)->(R->R)->(R->Prop)->R->Prop:=
- [f:R->R; d:R->R; D:R->Prop; x0:R](limit1_in
- [x:R] (Rdiv (Rminus (f x) (f x0)) (Rminus x x0))
- (D_x D x0) (d x0) x0).
-
-(*********)
-Lemma cont_deriv:(f,d:R->R;D:R->Prop;x0:R)
- (D_in f d D x0)->(continue_in f D x0).
-Unfold continue_in;Unfold D_in;Unfold limit1_in;Unfold limit_in;
- Unfold Rdiv;Simpl;Intros;Elim (H eps H0); Clear H;Intros;
- Elim H;Clear H;Intros; Elim (Req_EM (d x0) R0);Intro.
-Split with (Rmin R1 x);Split.
-Elim (Rmin_Rgt R1 x R0);Intros a b;
- Apply (b (conj (Rgt R1 R0) (Rgt x R0) Rlt_R0_R1 H)).
-Intros;Elim H3;Clear H3;Intros;
-Generalize (let (H1,H2)=(Rmin_Rgt R1 x (R_dist x1 x0)) in H1);
- Unfold Rgt;Intro;Elim (H5 H4);Clear H5;Intros;
- Generalize (H1 x1 (conj (D_x D x0 x1) (Rlt (R_dist x1 x0) x) H3 H6));
- Clear H1;Intro;Unfold D_x in H3;Elim H3;Intros.
-Rewrite H2 in H1;Unfold R_dist; Unfold R_dist in H1;
- Cut (Rlt (Rabsolu (Rminus (f x1) (f x0)))
- (Rmult eps (Rabsolu (Rminus x1 x0)))).
-Intro;Unfold R_dist in H5;
- Generalize (Rlt_monotony eps ``(Rabsolu (x1-x0))`` ``1`` H0 H5);
-Rewrite Rmult_1r;Intro;Apply Rlt_trans with r2:=``eps*(Rabsolu (x1-x0))``;
- Assumption.
-Rewrite (minus_R0 ``((f x1)-(f x0))*/(x1-x0)``) in H1;
- Rewrite Rabsolu_mult in H1; Cut ``x1-x0 <> 0``.
-Intro;Rewrite (Rabsolu_Rinv (Rminus x1 x0) H9) in H1;
- Generalize (Rlt_monotony ``(Rabsolu (x1-x0))``
- ``(Rabsolu ((f x1)-(f x0)))*/(Rabsolu (x1-x0))`` eps
- (Rabsolu_pos_lt ``x1-x0`` H9) H1);Intro; Rewrite Rmult_sym in H10;
- Rewrite Rmult_assoc in H10;Rewrite Rinv_l in H10.
-Rewrite Rmult_1r in H10;Rewrite Rmult_sym;Assumption.
-Apply Rabsolu_no_R0;Auto.
-Apply Rminus_eq_contra;Auto.
-(**)
- Split with (Rmin (Rmin (Rinv (Rplus R1 R1)) x)
- (Rmult eps (Rinv (Rabsolu (Rmult (Rplus R1 R1) (d x0))))));
- Split.
-Cut (Rgt (Rmin (Rinv (Rplus R1 R1)) x) R0).
-Cut (Rgt (Rmult eps (Rinv (Rabsolu (Rmult (Rplus R1 R1) (d x0))))) R0).
-Intros;Elim (Rmin_Rgt (Rmin (Rinv (Rplus R1 R1)) x)
- (Rmult eps (Rinv (Rabsolu (Rmult (Rplus R1 R1) (d x0))))) R0);
- Intros a b;
- Apply (b (conj (Rgt (Rmin (Rinv (Rplus R1 R1)) x) R0)
- (Rgt (Rmult eps (Rinv (Rabsolu (Rmult (Rplus R1 R1) (d x0))))) R0)
- H4 H3)).
-Apply Rmult_gt;Auto.
-Unfold Rgt;Apply Rlt_Rinv;Apply Rabsolu_pos_lt;Apply mult_non_zero;
- Split.
-DiscrR.
-Assumption.
-Elim (Rmin_Rgt (Rinv (Rplus R1 R1)) x R0);Intros a b;
- Cut (Rlt R0 (Rplus R1 R1)).
-Intro;Generalize (Rlt_Rinv (Rplus R1 R1) H3);Intro;
- Fold (Rgt (Rinv (Rplus R1 R1)) R0) in H4;
- Apply (b (conj (Rgt (Rinv (Rplus R1 R1)) R0) (Rgt x R0) H4 H)).
-Fourier.
-Intros;Elim H3;Clear H3;Intros;
- Generalize (let (H1,H2)=(Rmin_Rgt (Rmin (Rinv (Rplus R1 R1)) x)
- (Rmult eps (Rinv (Rabsolu (Rmult (Rplus R1 R1) (d x0)))))
- (R_dist x1 x0)) in H1);Unfold Rgt;Intro;Elim (H5 H4);Clear H5;
- Intros;
- Generalize (let (H1,H2)=(Rmin_Rgt (Rinv (Rplus R1 R1)) x
- (R_dist x1 x0)) in H1);Unfold Rgt;Intro;Elim (H7 H5);Clear H7;
- Intros;Clear H4 H5;
- Generalize (H1 x1 (conj (D_x D x0 x1) (Rlt (R_dist x1 x0) x) H3 H8));
- Clear H1;Intro;Unfold D_x in H3;Elim H3;Intros;
- Generalize (sym_not_eqT R x0 x1 H5);Clear H5;Intro H5;
- Generalize (Rminus_eq_contra x1 x0 H5);
- Intro;Generalize H1;Pattern 1 (d x0);
- Rewrite <-(let (H1,H2)=(Rmult_ne (d x0)) in H2);
- Rewrite <-(Rinv_l (Rminus x1 x0) H9); Unfold R_dist;Unfold 1 Rminus;
- Rewrite (Rmult_sym (Rminus (f x1) (f x0)) (Rinv (Rminus x1 x0)));
- Rewrite (Rmult_sym (Rmult (Rinv (Rminus x1 x0)) (Rminus x1 x0)) (d x0));
- Rewrite <-(Ropp_mul1 (d x0) (Rmult (Rinv (Rminus x1 x0)) (Rminus x1 x0)));
- Rewrite (Rmult_sym (Ropp (d x0))
- (Rmult (Rinv (Rminus x1 x0)) (Rminus x1 x0)));
- Rewrite (Rmult_assoc (Rinv (Rminus x1 x0)) (Rminus x1 x0) (Ropp (d x0)));
- Rewrite <-(Rmult_Rplus_distr (Rinv (Rminus x1 x0)) (Rminus (f x1) (f x0))
- (Rmult (Rminus x1 x0) (Ropp (d x0))));
- Rewrite (Rabsolu_mult (Rinv (Rminus x1 x0))
- (Rplus (Rminus (f x1) (f x0))
- (Rmult (Rminus x1 x0) (Ropp (d x0)))));
- Clear H1;Intro;Generalize (Rlt_monotony (Rabsolu (Rminus x1 x0))
- (Rmult (Rabsolu (Rinv (Rminus x1 x0)))
- (Rabsolu
- (Rplus (Rminus (f x1) (f x0))
- (Rmult (Rminus x1 x0) (Ropp (d x0)))))) eps
- (Rabsolu_pos_lt (Rminus x1 x0) H9) H1);
- Rewrite <-(Rmult_assoc (Rabsolu (Rminus x1 x0))
- (Rabsolu (Rinv (Rminus x1 x0)))
- (Rabsolu
- (Rplus (Rminus (f x1) (f x0))
- (Rmult (Rminus x1 x0) (Ropp (d x0))))));
- Rewrite (Rabsolu_Rinv (Rminus x1 x0) H9);
- Rewrite (Rinv_r (Rabsolu (Rminus x1 x0))
- (Rabsolu_no_R0 (Rminus x1 x0) H9));
- Rewrite (let (H1,H2)=(Rmult_ne (Rabsolu
- (Rplus (Rminus (f x1) (f x0))
- (Rmult (Rminus x1 x0) (Ropp (d x0)))))) in H2);
- Generalize (Rabsolu_triang_inv (Rminus (f x1) (f x0))
- (Rmult (Rminus x1 x0) (d x0)));Intro;
- Rewrite (Rmult_sym (Rminus x1 x0) (Ropp (d x0)));
- Rewrite (Ropp_mul1 (d x0) (Rminus x1 x0));
- Fold (Rminus (Rminus (f x1) (f x0)) (Rmult (d x0) (Rminus x1 x0)));
- Rewrite (Rmult_sym (Rminus x1 x0) (d x0)) in H10;
- Clear H1;Intro;Generalize (Rle_lt_trans
- (Rminus (Rabsolu (Rminus (f x1) (f x0)))
- (Rabsolu (Rmult (d x0) (Rminus x1 x0))))
- (Rabsolu
- (Rminus (Rminus (f x1) (f x0)) (Rmult (d x0) (Rminus x1 x0))))
- (Rmult (Rabsolu (Rminus x1 x0)) eps) H10 H1);
- Clear H1;Intro;
- Generalize (Rlt_compatibility (Rabsolu (Rmult (d x0) (Rminus x1 x0)))
- (Rminus (Rabsolu (Rminus (f x1) (f x0)))
- (Rabsolu (Rmult (d x0) (Rminus x1 x0))))
- (Rmult (Rabsolu (Rminus x1 x0)) eps) H1);
- Unfold 2 Rminus;Rewrite (Rplus_sym (Rabsolu (Rminus (f x1) (f x0)))
- (Ropp (Rabsolu (Rmult (d x0) (Rminus x1 x0)))));
- Rewrite <-(Rplus_assoc (Rabsolu (Rmult (d x0) (Rminus x1 x0)))
- (Ropp (Rabsolu (Rmult (d x0) (Rminus x1 x0))))
- (Rabsolu (Rminus (f x1) (f x0))));
- Rewrite (Rplus_Ropp_r (Rabsolu (Rmult (d x0) (Rminus x1 x0))));
- Rewrite (let (H1,H2)=(Rplus_ne (Rabsolu (Rminus (f x1) (f x0)))) in H2);
- Clear H1;Intro;Cut (Rlt (Rplus (Rabsolu (Rmult (d x0) (Rminus x1 x0)))
- (Rmult (Rabsolu (Rminus x1 x0)) eps)) eps).
-Intro;Apply (Rlt_trans (Rabsolu (Rminus (f x1) (f x0)))
- (Rplus (Rabsolu (Rmult (d x0) (Rminus x1 x0)))
- (Rmult (Rabsolu (Rminus x1 x0)) eps)) eps H1 H11).
-Clear H1 H5 H3 H10;Generalize (Rabsolu_pos_lt (d x0) H2);
- Intro;Unfold Rgt in H0;Generalize (Rlt_monotony eps (R_dist x1 x0)
- (Rinv (Rplus R1 R1)) H0 H7);Clear H7;Intro;
- Generalize (Rlt_monotony (Rabsolu (d x0)) (R_dist x1 x0)
- (Rmult eps (Rinv (Rabsolu (Rmult (Rplus R1 R1) (d x0))))) H1 H6);
- Clear H6;Intro;Rewrite (Rmult_sym eps (R_dist x1 x0)) in H3;
- Unfold R_dist in H3 H5;
- Rewrite <-(Rabsolu_mult (d x0) (Rminus x1 x0)) in H5;
- Rewrite (Rabsolu_mult (Rplus R1 R1) (d x0)) in H5;
- Cut ~(Rabsolu (Rplus R1 R1))==R0.
-Intro;Fold (Rgt (Rabsolu (d x0)) R0) in H1;
- Rewrite (Rinv_Rmult (Rabsolu (Rplus R1 R1)) (Rabsolu (d x0))
- H6 (imp_not_Req (Rabsolu (d x0)) R0
- (or_intror (Rlt (Rabsolu (d x0)) R0) (Rgt (Rabsolu (d x0)) R0) H1)))
- in H5;
- Rewrite (Rmult_sym (Rabsolu (d x0)) (Rmult eps
- (Rmult (Rinv (Rabsolu (Rplus R1 R1)))
- (Rinv (Rabsolu (d x0)))))) in H5;
- Rewrite <-(Rmult_assoc eps (Rinv (Rabsolu (Rplus R1 R1)))
- (Rinv (Rabsolu (d x0)))) in H5;
- Rewrite (Rmult_assoc (Rmult eps (Rinv (Rabsolu (Rplus R1 R1))))
- (Rinv (Rabsolu (d x0))) (Rabsolu (d x0))) in H5;
- Rewrite (Rinv_l (Rabsolu (d x0)) (imp_not_Req (Rabsolu (d x0)) R0
- (or_intror (Rlt (Rabsolu (d x0)) R0) (Rgt (Rabsolu (d x0)) R0) H1)))
- in H5;
- Rewrite (let (H1,H2)=(Rmult_ne (Rmult eps (Rinv (Rabsolu (Rplus R1 R1)))))
- in H1) in H5;Cut (Rabsolu (Rplus R1 R1))==(Rplus R1 R1).
-Intro;Rewrite H7 in H5;
- Generalize (Rplus_lt (Rabsolu (Rmult (d x0) (Rminus x1 x0)))
- (Rmult eps (Rinv (Rplus R1 R1)))
- (Rmult (Rabsolu (Rminus x1 x0)) eps)
- (Rmult eps (Rinv (Rplus R1 R1))) H5 H3);Intro;
- Rewrite eps2 in H10;Assumption.
-Unfold Rabsolu;Case (case_Rabsolu (Rplus R1 R1));Auto.
- Intro;Cut (Rlt R0 (Rplus R1 R1)).
-Intro;Generalize (Rlt_antisym R0 (Rplus R1 R1) H7);Intro;ElimType False;
- Auto.
-Fourier.
-Apply Rabsolu_no_R0.
-DiscrR.
-Qed.
-
-
-(*********)
-Lemma Dconst:(D:R->Prop)(y:R)(x0:R)(D_in [x:R]y [x:R]R0 D x0).
-Unfold D_in;Intros;Unfold limit1_in;Unfold limit_in;Unfold Rdiv;Intros;Simpl;
- Split with eps;Split;Auto.
-Intros;Rewrite (eq_Rminus y y (refl_eqT R y));
- Rewrite Rmult_Ol;Unfold R_dist;
- Rewrite (eq_Rminus R0 R0 (refl_eqT R R0));Unfold Rabsolu;
- Case (case_Rabsolu R0);Intro.
-Absurd (Rlt R0 R0);Auto.
-Red;Intro;Apply (Rlt_antirefl R0 H1).
-Unfold Rgt in H0;Assumption.
-Qed.
-
-(*********)
-Lemma Dx:(D:R->Prop)(x0:R)(D_in [x:R]x [x:R]R1 D x0).
-Unfold D_in;Unfold Rdiv;Intros;Unfold limit1_in;Unfold limit_in;Intros;Simpl;
- Split with eps;Split;Auto.
-Intros;Elim H0;Clear H0;Intros;Unfold D_x in H0;
- Elim H0;Intros;
- Rewrite (Rinv_r (Rminus x x0) (Rminus_eq_contra x x0
- (sym_not_eqT R x0 x H3)));
- Unfold R_dist;
- Rewrite (eq_Rminus R1 R1 (refl_eqT R R1));Unfold Rabsolu;
- Case (case_Rabsolu R0);Intro.
-Absurd (Rlt R0 R0);Auto.
-Red;Intro;Apply (Rlt_antirefl R0 r).
-Unfold Rgt in H;Assumption.
-Qed.
-
-(*********)
-Lemma Dadd:(D:R->Prop)(df,dg:R->R)(f,g:R->R)(x0:R)
- (D_in f df D x0)->(D_in g dg D x0)->
- (D_in [x:R](Rplus (f x) (g x)) [x:R](Rplus (df x) (dg x)) D x0).
-Unfold D_in;Intros;Generalize (limit_plus
- [x:R](Rmult (Rminus (f x) (f x0)) (Rinv (Rminus x x0)))
- [x:R](Rmult (Rminus (g x) (g x0)) (Rinv (Rminus x x0)))
- (D_x D x0) (df x0) (dg x0) x0 H H0);Clear H H0;
- Unfold limit1_in;Unfold limit_in;Simpl;Intros;
- Elim (H eps H0);Clear H;Intros;Elim H;Clear H;Intros;
- Split with x;Split;Auto;Intros;Generalize (H1 x1 H2);Clear H1;Intro;
- Rewrite (Rmult_sym (Rminus (f x1) (f x0)) (Rinv (Rminus x1 x0))) in H1;
- Rewrite (Rmult_sym (Rminus (g x1) (g x0)) (Rinv (Rminus x1 x0))) in H1;
- Rewrite <-(Rmult_Rplus_distr (Rinv (Rminus x1 x0))
- (Rminus (f x1) (f x0))
- (Rminus (g x1) (g x0))) in H1;
- Rewrite (Rmult_sym (Rinv (Rminus x1 x0))
- (Rplus (Rminus (f x1) (f x0)) (Rminus (g x1) (g x0)))) in H1;
- Cut (Rplus (Rminus (f x1) (f x0)) (Rminus (g x1) (g x0)))==
- (Rminus (Rplus (f x1) (g x1)) (Rplus (f x0) (g x0))).
-Intro;Rewrite H3 in H1;Assumption.
-Ring.
-Qed.
-
-(*********)
-Lemma Dmult:(D:R->Prop)(df,dg:R->R)(f,g:R->R)(x0:R)
- (D_in f df D x0)->(D_in g dg D x0)->
- (D_in [x:R](Rmult (f x) (g x))
- [x:R](Rplus (Rmult (df x) (g x)) (Rmult (f x) (dg x))) D x0).
-Intros;Unfold D_in;Generalize H H0;Intros;Unfold D_in in H H0;
- Generalize (cont_deriv f df D x0 H1);Unfold continue_in;Intro;
- Generalize (limit_mul
- [x:R](Rmult (Rminus (g x) (g x0)) (Rinv (Rminus x x0)))
- [x:R](f x) (D_x D x0) (dg x0) (f x0) x0 H0 H3);Intro;
- Cut (limit1_in [x:R](g x0) (D_x D x0) (g x0) x0).
-Intro;Generalize (limit_mul
- [x:R](Rmult (Rminus (f x) (f x0)) (Rinv (Rminus x x0)))
- [_:R](g x0) (D_x D x0) (df x0) (g x0) x0 H H5);Clear H H0 H1 H2 H3 H5;
- Intro;Generalize (limit_plus
- [x:R](Rmult (Rmult (Rminus (f x) (f x0)) (Rinv (Rminus x x0))) (g x0))
- [x:R](Rmult (Rmult (Rminus (g x) (g x0)) (Rinv (Rminus x x0)))
- (f x)) (D_x D x0) (Rmult (df x0) (g x0))
- (Rmult (dg x0) (f x0)) x0 H H4);
- Clear H4 H;Intro;Unfold limit1_in in H;Unfold limit_in in H;
- Simpl in H;Unfold limit1_in;Unfold limit_in;Simpl;Intros;
- Elim (H eps H0);Clear H;Intros;Elim H;Clear H;Intros;
- Split with x;Split;Auto;Intros;Generalize (H1 x1 H2);Clear H1;Intro;
- Rewrite (Rmult_sym (Rminus (f x1) (f x0)) (Rinv (Rminus x1 x0))) in H1;
- Rewrite (Rmult_sym (Rminus (g x1) (g x0)) (Rinv (Rminus x1 x0))) in H1;
- Rewrite (Rmult_assoc (Rinv (Rminus x1 x0)) (Rminus (f x1) (f x0))
- (g x0)) in H1;
- Rewrite (Rmult_assoc (Rinv (Rminus x1 x0)) (Rminus (g x1) (g x0))
- (f x1)) in H1;
- Rewrite <-(Rmult_Rplus_distr (Rinv (Rminus x1 x0))
- (Rmult (Rminus (f x1) (f x0)) (g x0))
- (Rmult (Rminus (g x1) (g x0)) (f x1))) in H1;
- Rewrite (Rmult_sym (Rinv (Rminus x1 x0))
- (Rplus (Rmult (Rminus (f x1) (f x0)) (g x0))
- (Rmult (Rminus (g x1) (g x0)) (f x1)))) in H1;
- Rewrite (Rmult_sym (dg x0) (f x0)) in H1;
- Cut (Rplus (Rmult (Rminus (f x1) (f x0)) (g x0))
- (Rmult (Rminus (g x1) (g x0)) (f x1)))==
- (Rminus (Rmult (f x1) (g x1)) (Rmult (f x0) (g x0))).
-Intro;Rewrite H3 in H1;Assumption.
-Ring.
-Unfold limit1_in;Unfold limit_in;Simpl;Intros;
- Split with eps;Split;Auto;Intros;Elim (R_dist_refl (g x0) (g x0));
- Intros a b;Rewrite (b (refl_eqT R (g x0)));Unfold Rgt in H;Assumption.
-Qed.
-
-(*********)
-Lemma Dmult_const:(D:R->Prop)(f,df:R->R)(x0:R)(a:R)(D_in f df D x0)->
- (D_in [x:R](Rmult a (f x)) ([x:R](Rmult a (df x))) D x0).
-Intros;Generalize (Dmult D [_:R]R0 df [_:R]a f x0 (Dconst D a x0) H);
- Unfold D_in;Intros;
- Rewrite (Rmult_Ol (f x0)) in H0;
- Rewrite (let (H1,H2)=(Rplus_ne (Rmult a (df x0))) in H2) in H0;
- Assumption.
-Qed.
-
-(*********)
-Lemma Dopp:(D:R->Prop)(f,df:R->R)(x0:R)(D_in f df D x0)->
- (D_in [x:R](Ropp (f x)) ([x:R](Ropp (df x))) D x0).
-Intros;Generalize (Dmult_const D f df x0 (Ropp R1) H); Unfold D_in;
- Unfold limit1_in;Unfold limit_in;Intros;
- Generalize (H0 eps H1);Clear H0;Intro;Elim H0;Clear H0;Intros;
- Elim H0;Clear H0;Simpl;Intros;Split with x;Split;Auto.
-Intros;Generalize (H2 x1 H3);Clear H2;Intro;Rewrite Ropp_mul1 in H2;
- Rewrite Ropp_mul1 in H2;Rewrite Ropp_mul1 in H2;
- Rewrite (let (H1,H2)=(Rmult_ne (f x1)) in H2) in H2;
- Rewrite (let (H1,H2)=(Rmult_ne (f x0)) in H2) in H2;
- Rewrite (let (H1,H2)=(Rmult_ne (df x0)) in H2) in H2;Assumption.
-Qed.
-
-(*********)
-Lemma Dminus:(D:R->Prop)(df,dg:R->R)(f,g:R->R)(x0:R)
- (D_in f df D x0)->(D_in g dg D x0)->
- (D_in [x:R](Rminus (f x) (g x)) [x:R](Rminus (df x) (dg x)) D x0).
-Unfold Rminus;Intros;Generalize (Dopp D g dg x0 H0);Intro;
- Apply (Dadd D df [x:R](Ropp (dg x)) f [x:R](Ropp (g x)) x0);Assumption.
-Qed.
-
-(*********)
-Lemma Dx_pow_n:(n:nat)(D:R->Prop)(x0:R)
- (D_in [x:R](pow x n)
- [x:R](Rmult (INR n) (pow x (minus n (1)))) D x0).
-Induction n;Intros.
-Simpl; Rewrite Rmult_Ol; Apply Dconst.
-Intros;Cut n0=(minus (S n0) (1));
- [ Intro a; Rewrite <- a;Clear a | Simpl; Apply minus_n_O ].
-Generalize (Dmult D [_:R]R1
- [x:R](Rmult (INR n0) (pow x (minus n0 (1)))) [x:R]x [x:R](pow x n0)
- x0 (Dx D x0) (H D x0));Unfold D_in;Unfold limit1_in;Unfold limit_in;
- Simpl;Intros;
- Elim (H0 eps H1);Clear H0;Intros;Elim H0;Clear H0;Intros;
- Split with x;Split;Auto.
-Intros;Generalize (H2 x1 H3);Clear H2 H3;Intro;
- Rewrite (let (H1,H2)=(Rmult_ne (pow x0 n0)) in H2) in H2;
- Rewrite (tech_pow_Rmult x1 n0) in H2;
- Rewrite (tech_pow_Rmult x0 n0) in H2;
- Rewrite (Rmult_sym (INR n0) (pow x0 (minus n0 (1)))) in H2;
- Rewrite <-(Rmult_assoc x0 (pow x0 (minus n0 (1))) (INR n0)) in H2;
- Rewrite (tech_pow_Rmult x0 (minus n0 (1))) in H2;
- Elim (classic (n0=O));Intro cond.
-Rewrite cond in H2;Rewrite cond;Simpl in H2;Simpl;
- Cut (Rplus R1 (Rmult (Rmult x0 R1) R0))==(Rmult R1 R1);
- [Intro A; Rewrite A in H2; Assumption|Ring].
-Cut ~(n0=O)->(S (minus n0 (1)))=n0;[Intro|Omega];
- Rewrite (H3 cond) in H2; Rewrite (Rmult_sym (pow x0 n0) (INR n0)) in H2;
- Rewrite (tech_pow_Rplus x0 n0 n0) in H2; Assumption.
-Qed.
-
-(*********)
-Lemma Dcomp:(Df,Dg:R->Prop)(df,dg:R->R)(f,g:R->R)(x0:R)
- (D_in f df Df x0)->(D_in g dg Dg (f x0))->
- (D_in [x:R](g (f x)) [x:R](Rmult (df x) (dg (f x)))
- (Dgf Df Dg f) x0).
-Intros Df Dg df dg f g x0 H H0;Generalize H H0;Unfold D_in;Unfold Rdiv;Intros;
-Generalize (limit_comp f [x:R](Rmult (Rminus (g x) (g (f x0)))
- (Rinv (Rminus x (f x0)))) (D_x Df x0)
- (D_x Dg (f x0))
- (f x0) (dg (f x0)) x0);Intro;
- Generalize (cont_deriv f df Df x0 H);Intro;Unfold continue_in in H4;
- Generalize (H3 H4 H2);Clear H3;Intro;
- Generalize (limit_mul [x:R](Rmult (Rminus (g (f x)) (g (f x0)))
- (Rinv (Rminus (f x) (f x0))))
- [x:R](Rmult (Rminus (f x) (f x0))
- (Rinv (Rminus x x0)))
- (Dgf (D_x Df x0) (D_x Dg (f x0)) f)
- (dg (f x0)) (df x0) x0 H3);Intro;
- Cut (limit1_in
- [x:R](Rmult (Rminus (f x) (f x0)) (Rinv (Rminus x x0)))
- (Dgf (D_x Df x0) (D_x Dg (f x0)) f) (df x0) x0).
-Intro;Generalize (H5 H6);Clear H5;Intro;
- Generalize (limit_mul
- [x:R](Rmult (Rminus (f x) (f x0)) (Rinv (Rminus x x0)))
- [x:R](dg (f x0))
- (D_x Df x0) (df x0) (dg (f x0)) x0 H1
- (limit_free [x:R](dg (f x0)) (D_x Df x0) x0 x0));
- Intro;
- Unfold limit1_in;Unfold limit_in;Simpl;Unfold limit1_in in H5 H7;
- Unfold limit_in in H5 H7;Simpl in H5 H7;Intros;Elim (H5 eps H8);
- Elim (H7 eps H8);Clear H5 H7;Intros;Elim H5;Elim H7;Clear H5 H7;
- Intros;Split with (Rmin x x1);Split.
-Elim (Rmin_Rgt x x1 R0);Intros a b;
- Apply (b (conj (Rgt x R0) (Rgt x1 R0) H9 H5));Clear a b.
-Intros;Elim H11;Clear H11;Intros;Elim (Rmin_Rgt x x1 (R_dist x2 x0));
- Intros a b;Clear b;Unfold Rgt in a;Elim (a H12);Clear H5 a;Intros;
- Unfold D_x Dgf in H11 H7 H10;Clear H12;
- Elim (classic (f x2)==(f x0));Intro.
-Elim H11;Clear H11;Intros;Elim H11;Clear H11;Intros;
- Generalize (H10 x2 (conj (Df x2)/\~x0==x2 (Rlt (R_dist x2 x0) x)
- (conj (Df x2) ~x0==x2 H11 H14) H5));Intro;
- Rewrite (eq_Rminus (f x2) (f x0) H12) in H16;
- Rewrite (Rmult_Ol (Rinv (Rminus x2 x0))) in H16;
- Rewrite (Rmult_Ol (dg (f x0))) in H16;
- Rewrite H12;
- Rewrite (eq_Rminus (g (f x0)) (g (f x0)) (refl_eqT R (g (f x0))));
- Rewrite (Rmult_Ol (Rinv (Rminus x2 x0)));Assumption.
-Clear H10 H5;Elim H11;Clear H11;Intros;Elim H5;Clear H5;Intros;
-Cut (((Df x2)/\~x0==x2)/\(Dg (f x2))/\~(f x0)==(f x2))
- /\(Rlt (R_dist x2 x0) x1);Auto;Intro;
- Generalize (H7 x2 H14);Intro;
- Generalize (Rminus_eq_contra (f x2) (f x0) H12);Intro;
- Rewrite (Rmult_assoc (Rminus (g (f x2)) (g (f x0)))
- (Rinv (Rminus (f x2) (f x0)))
- (Rmult (Rminus (f x2) (f x0)) (Rinv (Rminus x2 x0)))) in H15;
- Rewrite <-(Rmult_assoc (Rinv (Rminus (f x2) (f x0)))
- (Rminus (f x2) (f x0)) (Rinv (Rminus x2 x0))) in H15;
- Rewrite (Rinv_l (Rminus (f x2) (f x0)) H16) in H15;
- Rewrite (let (H1,H2)=(Rmult_ne (Rinv (Rminus x2 x0))) in H2) in H15;
- Rewrite (Rmult_sym (df x0) (dg (f x0)));Assumption.
-Clear H5 H3 H4 H2;Unfold limit1_in;Unfold limit_in;Simpl;
- Unfold limit1_in in H1;Unfold limit_in in H1;Simpl in H1;Intros;
- Elim (H1 eps H2);Clear H1;Intros;Elim H1;Clear H1;Intros;
- Split with x;Split;Auto;Intros;Unfold D_x Dgf in H4 H3;
- Elim H4;Clear H4;Intros;Elim H4;Clear H4;Intros;
- Exact (H3 x1 (conj (Df x1)/\~x0==x1 (Rlt (R_dist x1 x0) x) H4 H5)).
-Qed.
-
-(*********)
-Lemma D_pow_n:(n:nat)(D:R->Prop)(x0:R)(expr,dexpr:R->R)
- (D_in expr dexpr D x0)-> (D_in [x:R](pow (expr x) n)
- [x:R](Rmult (Rmult (INR n) (pow (expr x) (minus n (1)))) (dexpr x))
- (Dgf D D expr) x0).
-Intros n D x0 expr dexpr H;
- Generalize (Dcomp D D dexpr [x:R](Rmult (INR n) (pow x (minus n (1))))
- expr [x:R](pow x n) x0 H (Dx_pow_n n D (expr x0)));
- Intro; Unfold D_in; Unfold limit1_in; Unfold limit_in;Simpl;Intros;
- Unfold D_in in H0; Unfold limit1_in in H0; Unfold limit_in in H0;Simpl in H0;
- Elim (H0 eps H1);Clear H0;Intros;Elim H0;Clear H0;Intros;Split with x;Split;
- Intros; Auto.
-Cut ``((dexpr x0)*((INR n)*(pow (expr x0) (minus n (S O)))))==
- ((INR n)*(pow (expr x0) (minus n (S O)))*(dexpr x0))``;
- [Intro Rew;Rewrite <- Rew;Exact (H2 x1 H3)|Ring].
-Qed.
-