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Diffstat (limited to 'theories/Numbers/Cyclic/DoubleCyclic/DoubleMul.v')
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diff --git a/theories/Numbers/Cyclic/DoubleCyclic/DoubleMul.v b/theories/Numbers/Cyclic/DoubleCyclic/DoubleMul.v deleted file mode 100644 index b99013900..000000000 --- a/theories/Numbers/Cyclic/DoubleCyclic/DoubleMul.v +++ /dev/null @@ -1,621 +0,0 @@ -(************************************************************************) -(* v * The Coq Proof Assistant / The Coq Development Team *) -(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2016 *) -(* \VV/ **************************************************************) -(* // * This file is distributed under the terms of the *) -(* * GNU Lesser General Public License Version 2.1 *) -(************************************************************************) -(* Benjamin Gregoire, Laurent Thery, INRIA, 2007 *) -(************************************************************************) - -Set Implicit Arguments. - -Require Import ZArith. -Require Import BigNumPrelude. -Require Import DoubleType. -Require Import DoubleBase. - -Local Open Scope Z_scope. - -Section DoubleMul. - Variable w : Type. - Variable w_0 : w. - Variable w_1 : w. - Variable w_WW : w -> w -> zn2z w. - Variable w_W0 : w -> zn2z w. - Variable w_0W : w -> zn2z w. - Variable w_compare : w -> w -> comparison. - Variable w_succ : w -> w. - Variable w_add_c : w -> w -> carry w. - Variable w_add : w -> w -> w. - Variable w_sub: w -> w -> w. - Variable w_mul_c : w -> w -> zn2z w. - Variable w_mul : w -> w -> w. - Variable w_square_c : w -> zn2z w. - Variable ww_add_c : zn2z w -> zn2z w -> carry (zn2z w). - Variable ww_add : zn2z w -> zn2z w -> zn2z w. - Variable ww_add_carry : zn2z w -> zn2z w -> zn2z w. - Variable ww_sub_c : zn2z w -> zn2z w -> carry (zn2z w). - Variable ww_sub : zn2z w -> zn2z w -> zn2z w. - - (* ** Multiplication ** *) - - (* (xh*B+xl) (yh*B + yl) - xh*yh = hh = |hhh|hhl|B2 - xh*yl +xl*yh = cc = |cch|ccl|B - xl*yl = ll = |llh|lll - *) - - Definition double_mul_c (cross:w->w->w->w->zn2z w -> zn2z w -> w*zn2z w) x y := - match x, y with - | W0, _ => W0 - | _, W0 => W0 - | WW xh xl, WW yh yl => - let hh := w_mul_c xh yh in - let ll := w_mul_c xl yl in - let (wc,cc) := cross xh xl yh yl hh ll in - match cc with - | W0 => WW (ww_add hh (w_W0 wc)) ll - | WW cch ccl => - match ww_add_c (w_W0 ccl) ll with - | C0 l => WW (ww_add hh (w_WW wc cch)) l - | C1 l => WW (ww_add_carry hh (w_WW wc cch)) l - end - end - end. - - Definition ww_mul_c := - double_mul_c - (fun xh xl yh yl hh ll=> - match ww_add_c (w_mul_c xh yl) (w_mul_c xl yh) with - | C0 cc => (w_0, cc) - | C1 cc => (w_1, cc) - end). - - Definition w_2 := w_add w_1 w_1. - - Definition kara_prod xh xl yh yl hh ll := - match ww_add_c hh ll with - C0 m => - match w_compare xl xh with - Eq => (w_0, m) - | Lt => - match w_compare yl yh with - Eq => (w_0, m) - | Lt => (w_0, ww_sub m (w_mul_c (w_sub xh xl) (w_sub yh yl))) - | Gt => match ww_add_c m (w_mul_c (w_sub xh xl) (w_sub yl yh)) with - C1 m1 => (w_1, m1) | C0 m1 => (w_0, m1) - end - end - | Gt => - match w_compare yl yh with - Eq => (w_0, m) - | Lt => match ww_add_c m (w_mul_c (w_sub xl xh) (w_sub yh yl)) with - C1 m1 => (w_1, m1) | C0 m1 => (w_0, m1) - end - | Gt => (w_0, ww_sub m (w_mul_c (w_sub xl xh) (w_sub yl yh))) - end - end - | C1 m => - match w_compare xl xh with - Eq => (w_1, m) - | Lt => - match w_compare yl yh with - Eq => (w_1, m) - | Lt => match ww_sub_c m (w_mul_c (w_sub xh xl) (w_sub yh yl)) with - C0 m1 => (w_1, m1) | C1 m1 => (w_0, m1) - end - | Gt => match ww_add_c m (w_mul_c (w_sub xh xl) (w_sub yl yh)) with - C1 m1 => (w_2, m1) | C0 m1 => (w_1, m1) - end - end - | Gt => - match w_compare yl yh with - Eq => (w_1, m) - | Lt => match ww_add_c m (w_mul_c (w_sub xl xh) (w_sub yh yl)) with - C1 m1 => (w_2, m1) | C0 m1 => (w_1, m1) - end - | Gt => match ww_sub_c m (w_mul_c (w_sub xl xh) (w_sub yl yh)) with - C1 m1 => (w_0, m1) | C0 m1 => (w_1, m1) - end - end - end - end. - - Definition ww_karatsuba_c := double_mul_c kara_prod. - - Definition ww_mul x y := - match x, y with - | W0, _ => W0 - | _, W0 => W0 - | WW xh xl, WW yh yl => - let ccl := w_add (w_mul xh yl) (w_mul xl yh) in - ww_add (w_W0 ccl) (w_mul_c xl yl) - end. - - Definition ww_square_c x := - match x with - | W0 => W0 - | WW xh xl => - let hh := w_square_c xh in - let ll := w_square_c xl in - let xhxl := w_mul_c xh xl in - let (wc,cc) := - match ww_add_c xhxl xhxl with - | C0 cc => (w_0, cc) - | C1 cc => (w_1, cc) - end in - match cc with - | W0 => WW (ww_add hh (w_W0 wc)) ll - | WW cch ccl => - match ww_add_c (w_W0 ccl) ll with - | C0 l => WW (ww_add hh (w_WW wc cch)) l - | C1 l => WW (ww_add_carry hh (w_WW wc cch)) l - end - end - end. - - Section DoubleMulAddn1. - Variable w_mul_add : w -> w -> w -> w * w. - - Fixpoint double_mul_add_n1 (n:nat) : word w n -> w -> w -> w * word w n := - match n return word w n -> w -> w -> w * word w n with - | O => w_mul_add - | S n1 => - let mul_add := double_mul_add_n1 n1 in - fun x y r => - match x with - | W0 => (w_0,extend w_0W n1 r) - | WW xh xl => - let (rl,l) := mul_add xl y r in - let (rh,h) := mul_add xh y rl in - (rh, double_WW w_WW n1 h l) - end - end. - - End DoubleMulAddn1. - - Section DoubleMulAddmn1. - Variable wn: Type. - Variable extend_n : w -> wn. - Variable wn_0W : wn -> zn2z wn. - Variable wn_WW : wn -> wn -> zn2z wn. - Variable w_mul_add_n1 : wn -> w -> w -> w*wn. - Fixpoint double_mul_add_mn1 (m:nat) : - word wn m -> w -> w -> w*word wn m := - match m return word wn m -> w -> w -> w*word wn m with - | O => w_mul_add_n1 - | S m1 => - let mul_add := double_mul_add_mn1 m1 in - fun x y r => - match x with - | W0 => (w_0,extend wn_0W m1 (extend_n r)) - | WW xh xl => - let (rl,l) := mul_add xl y r in - let (rh,h) := mul_add xh y rl in - (rh, double_WW wn_WW m1 h l) - end - end. - - End DoubleMulAddmn1. - - Definition w_mul_add x y r := - match w_mul_c x y with - | W0 => (w_0, r) - | WW h l => - match w_add_c l r with - | C0 lr => (h,lr) - | C1 lr => (w_succ h, lr) - end - end. - - - (*Section DoubleProof. *) - Variable w_digits : positive. - Variable w_to_Z : w -> Z. - - Notation wB := (base w_digits). - Notation wwB := (base (ww_digits w_digits)). - Notation "[| x |]" := (w_to_Z x) (at level 0, x at level 99). - Notation "[+| c |]" := - (interp_carry 1 wB w_to_Z c) (at level 0, c at level 99). - Notation "[-| c |]" := - (interp_carry (-1) wB w_to_Z c) (at level 0, c at level 99). - - Notation "[[ x ]]" := (ww_to_Z w_digits w_to_Z x)(at level 0, x at level 99). - Notation "[+[ c ]]" := - (interp_carry 1 wwB (ww_to_Z w_digits w_to_Z) c) - (at level 0, c at level 99). - Notation "[-[ c ]]" := - (interp_carry (-1) wwB (ww_to_Z w_digits w_to_Z) c) - (at level 0, c at level 99). - - Notation "[|| x ||]" := - (zn2z_to_Z wwB (ww_to_Z w_digits w_to_Z) x) (at level 0, x at level 99). - - Notation "[! n | x !]" := (double_to_Z w_digits w_to_Z n x) - (at level 0, x at level 99). - - Variable spec_more_than_1_digit: 1 < Zpos w_digits. - Variable spec_w_0 : [|w_0|] = 0. - Variable spec_w_1 : [|w_1|] = 1. - - Variable spec_to_Z : forall x, 0 <= [|x|] < wB. - - Variable spec_w_WW : forall h l, [[w_WW h l]] = [|h|] * wB + [|l|]. - Variable spec_w_W0 : forall h, [[w_W0 h]] = [|h|] * wB. - Variable spec_w_0W : forall l, [[w_0W l]] = [|l|]. - Variable spec_w_compare : - forall x y, w_compare x y = Z.compare [|x|] [|y|]. - Variable spec_w_succ : forall x, [|w_succ x|] = ([|x|] + 1) mod wB. - Variable spec_w_add_c : forall x y, [+|w_add_c x y|] = [|x|] + [|y|]. - Variable spec_w_add : forall x y, [|w_add x y|] = ([|x|] + [|y|]) mod wB. - Variable spec_w_sub : forall x y, [|w_sub x y|] = ([|x|] - [|y|]) mod wB. - - Variable spec_w_mul_c : forall x y, [[ w_mul_c x y ]] = [|x|] * [|y|]. - Variable spec_w_mul : forall x y, [|w_mul x y|] = ([|x|] * [|y|]) mod wB. - Variable spec_w_square_c : forall x, [[ w_square_c x]] = [|x|] * [|x|]. - - Variable spec_ww_add_c : forall x y, [+[ww_add_c x y]] = [[x]] + [[y]]. - Variable spec_ww_add : forall x y, [[ww_add x y]] = ([[x]] + [[y]]) mod wwB. - Variable spec_ww_add_carry : - forall x y, [[ww_add_carry x y]] = ([[x]] + [[y]] + 1) mod wwB. - Variable spec_ww_sub : forall x y, [[ww_sub x y]] = ([[x]] - [[y]]) mod wwB. - Variable spec_ww_sub_c : forall x y, [-[ww_sub_c x y]] = [[x]] - [[y]]. - - - Lemma spec_ww_to_Z : forall x, 0 <= [[x]] < wwB. - Proof. intros x;apply spec_ww_to_Z;auto. Qed. - - Lemma spec_ww_to_Z_wBwB : forall x, 0 <= [[x]] < wB^2. - Proof. rewrite <- wwB_wBwB;apply spec_ww_to_Z. Qed. - - Hint Resolve spec_ww_to_Z spec_ww_to_Z_wBwB : mult. - Ltac zarith := auto with zarith mult. - - Lemma wBwB_lex: forall a b c d, - a * wB^2 + [[b]] <= c * wB^2 + [[d]] -> - a <= c. - Proof. - intros a b c d H; apply beta_lex with [[b]] [[d]] (wB^2);zarith. - Qed. - - Lemma wBwB_lex_inv: forall a b c d, - a < c -> - a * wB^2 + [[b]] < c * wB^2 + [[d]]. - Proof. - intros a b c d H; apply beta_lex_inv; zarith. - Qed. - - Lemma sum_mul_carry : forall xh xl yh yl wc cc, - [|wc|]*wB^2 + [[cc]] = [|xh|] * [|yl|] + [|xl|] * [|yh|] -> - 0 <= [|wc|] <= 1. - Proof. - intros. - apply (sum_mul_carry [|xh|] [|xl|] [|yh|] [|yl|] [|wc|][[cc]] wB);zarith. - apply wB_pos. - Qed. - - Theorem mult_add_ineq: forall xH yH crossH, - 0 <= [|xH|] * [|yH|] + [|crossH|] < wwB. - Proof. - intros;rewrite wwB_wBwB;apply mult_add_ineq;zarith. - Qed. - - Hint Resolve mult_add_ineq : mult. - - Lemma spec_mul_aux : forall xh xl yh yl wc (cc:zn2z w) hh ll, - [[hh]] = [|xh|] * [|yh|] -> - [[ll]] = [|xl|] * [|yl|] -> - [|wc|]*wB^2 + [[cc]] = [|xh|] * [|yl|] + [|xl|] * [|yh|] -> - [||match cc with - | W0 => WW (ww_add hh (w_W0 wc)) ll - | WW cch ccl => - match ww_add_c (w_W0 ccl) ll with - | C0 l => WW (ww_add hh (w_WW wc cch)) l - | C1 l => WW (ww_add_carry hh (w_WW wc cch)) l - end - end||] = ([|xh|] * wB + [|xl|]) * ([|yh|] * wB + [|yl|]). - Proof. - intros;assert (U1 := wB_pos w_digits). - replace (([|xh|] * wB + [|xl|]) * ([|yh|] * wB + [|yl|])) with - ([|xh|]*[|yh|]*wB^2 + ([|xh|]*[|yl|] + [|xl|]*[|yh|])*wB + [|xl|]*[|yl|]). - 2:ring. rewrite <- H1;rewrite <- H;rewrite <- H0. - assert (H2 := sum_mul_carry _ _ _ _ _ _ H1). - destruct cc as [ | cch ccl]; simpl zn2z_to_Z; simpl ww_to_Z. - rewrite spec_ww_add;rewrite spec_w_W0;rewrite Zmod_small; - rewrite wwB_wBwB. ring. - rewrite <- (Z.add_0_r ([|wc|]*wB));rewrite H;apply mult_add_ineq3;zarith. - simpl ww_to_Z in H1. assert (U:=spec_to_Z cch). - assert ([|wc|]*wB + [|cch|] <= 2*wB - 3). - destruct (Z_le_gt_dec ([|wc|]*wB + [|cch|]) (2*wB - 3)) as [Hle|Hgt];trivial. - assert ([|xh|] * [|yl|] + [|xl|] * [|yh|] <= (2*wB - 4)*wB + 2). - ring_simplify ((2*wB - 4)*wB + 2). - assert (H4 := Zmult_lt_b _ _ _ (spec_to_Z xh) (spec_to_Z yl)). - assert (H5 := Zmult_lt_b _ _ _ (spec_to_Z xl) (spec_to_Z yh)). - omega. - generalize H3;clear H3;rewrite <- H1. - rewrite Z.add_assoc; rewrite Z.pow_2_r; rewrite Z.mul_assoc; - rewrite <- Z.mul_add_distr_r. - assert (((2 * wB - 4) + 2)*wB <= ([|wc|] * wB + [|cch|])*wB). - apply Z.mul_le_mono_nonneg;zarith. - rewrite Z.mul_add_distr_r in H3. - intros. assert (U2 := spec_to_Z ccl);omega. - generalize (spec_ww_add_c (w_W0 ccl) ll);destruct (ww_add_c (w_W0 ccl) ll) - as [l|l];unfold interp_carry;rewrite spec_w_W0;try rewrite Z.mul_1_l; - simpl zn2z_to_Z; - try rewrite spec_ww_add;try rewrite spec_ww_add_carry;rewrite spec_w_WW; - rewrite Zmod_small;rewrite wwB_wBwB;intros. - rewrite H4;ring. rewrite H;apply mult_add_ineq2;zarith. - rewrite Z.add_assoc;rewrite Z.mul_add_distr_r. - rewrite Z.mul_1_l;rewrite <- Z.add_assoc;rewrite H4;ring. - repeat rewrite <- Z.add_assoc;rewrite H;apply mult_add_ineq2;zarith. - Qed. - - Lemma spec_double_mul_c : forall cross:w->w->w->w->zn2z w -> zn2z w -> w*zn2z w, - (forall xh xl yh yl hh ll, - [[hh]] = [|xh|]*[|yh|] -> - [[ll]] = [|xl|]*[|yl|] -> - let (wc,cc) := cross xh xl yh yl hh ll in - [|wc|]*wwB + [[cc]] = [|xh|]*[|yl|] + [|xl|]*[|yh|]) -> - forall x y, [||double_mul_c cross x y||] = [[x]] * [[y]]. - Proof. - intros cross Hcross x y;destruct x as [ |xh xl];simpl;trivial. - destruct y as [ |yh yl];simpl. rewrite Z.mul_0_r;trivial. - assert (H1:= spec_w_mul_c xh yh);assert (H2:= spec_w_mul_c xl yl). - generalize (Hcross _ _ _ _ _ _ H1 H2). - destruct (cross xh xl yh yl (w_mul_c xh yh) (w_mul_c xl yl)) as (wc,cc). - intros;apply spec_mul_aux;trivial. - rewrite <- wwB_wBwB;trivial. - Qed. - - Lemma spec_ww_mul_c : forall x y, [||ww_mul_c x y||] = [[x]] * [[y]]. - Proof. - intros x y;unfold ww_mul_c;apply spec_double_mul_c. - intros xh xl yh yl hh ll H1 H2. - generalize (spec_ww_add_c (w_mul_c xh yl) (w_mul_c xl yh)); - destruct (ww_add_c (w_mul_c xh yl) (w_mul_c xl yh)) as [c|c]; - unfold interp_carry;repeat rewrite spec_w_mul_c;intros H; - (rewrite spec_w_0 || rewrite spec_w_1);rewrite H;ring. - Qed. - - Lemma spec_w_2: [|w_2|] = 2. - unfold w_2; rewrite spec_w_add; rewrite spec_w_1; simpl. - apply Zmod_small; split; auto with zarith. - rewrite <- (Z.pow_1_r 2); unfold base; apply Zpower_lt_monotone; auto with zarith. - Qed. - - Lemma kara_prod_aux : forall xh xl yh yl, - xh*yh + xl*yl - (xh-xl)*(yh-yl) = xh*yl + xl*yh. - Proof. intros;ring. Qed. - - Lemma spec_kara_prod : forall xh xl yh yl hh ll, - [[hh]] = [|xh|]*[|yh|] -> - [[ll]] = [|xl|]*[|yl|] -> - let (wc,cc) := kara_prod xh xl yh yl hh ll in - [|wc|]*wwB + [[cc]] = [|xh|]*[|yl|] + [|xl|]*[|yh|]. - Proof. - intros xh xl yh yl hh ll H H0; rewrite <- kara_prod_aux; - rewrite <- H; rewrite <- H0; unfold kara_prod. - assert (Hxh := (spec_to_Z xh)); assert (Hxl := (spec_to_Z xl)); - assert (Hyh := (spec_to_Z yh)); assert (Hyl := (spec_to_Z yl)). - generalize (spec_ww_add_c hh ll); case (ww_add_c hh ll); - intros z Hz; rewrite <- Hz; unfold interp_carry; assert (Hz1 := (spec_ww_to_Z z)). - rewrite spec_w_compare; case Z.compare_spec; intros Hxlh; - try rewrite Hxlh; try rewrite spec_w_0; try (ring; fail). - rewrite spec_w_compare; case Z.compare_spec; intros Hylh. - rewrite Hylh; rewrite spec_w_0; try (ring; fail). - rewrite spec_w_0; try (ring; fail). - repeat (rewrite spec_ww_sub || rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - split; auto with zarith. - simpl in Hz; rewrite Hz; rewrite H; rewrite H0. - rewrite kara_prod_aux; apply Z.add_nonneg_nonneg; apply Z.mul_nonneg_nonneg; auto with zarith. - apply Z.le_lt_trans with ([[z]]-0); auto with zarith. - unfold Z.sub; apply Z.add_le_mono_l; apply Z.le_0_sub; simpl; rewrite Z.opp_involutive. - apply Z.mul_nonneg_nonneg; auto with zarith. - match goal with |- context[ww_add_c ?x ?y] => - generalize (spec_ww_add_c x y); case (ww_add_c x y); try rewrite spec_w_0; - intros z1 Hz2 - end. - simpl in Hz2; rewrite Hz2; repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - rewrite spec_w_1; unfold interp_carry in Hz2; rewrite Hz2; - repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - rewrite spec_w_compare; case Z.compare_spec; intros Hylh. - rewrite Hylh; rewrite spec_w_0; try (ring; fail). - match goal with |- context[ww_add_c ?x ?y] => - generalize (spec_ww_add_c x y); case (ww_add_c x y); try rewrite spec_w_0; - intros z1 Hz2 - end. - simpl in Hz2; rewrite Hz2; repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - rewrite spec_w_1; unfold interp_carry in Hz2; rewrite Hz2; - repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - rewrite spec_w_0; try (ring; fail). - repeat (rewrite spec_ww_sub || rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - split. - match goal with |- context[(?x - ?y) * (?z - ?t)] => - replace ((x - y) * (z - t)) with ((y - x) * (t - z)); [idtac | ring] - end. - simpl in Hz; rewrite Hz; rewrite H; rewrite H0. - rewrite kara_prod_aux; apply Z.add_nonneg_nonneg; apply Z.mul_nonneg_nonneg; auto with zarith. - apply Z.le_lt_trans with ([[z]]-0); auto with zarith. - unfold Z.sub; apply Z.add_le_mono_l; apply Z.le_0_sub; simpl; rewrite Z.opp_involutive. - apply Z.mul_nonneg_nonneg; auto with zarith. - (** there is a carry in hh + ll **) - rewrite Z.mul_1_l. - rewrite spec_w_compare; case Z.compare_spec; intros Hxlh; - try rewrite Hxlh; try rewrite spec_w_1; try (ring; fail). - rewrite spec_w_compare; case Z.compare_spec; intros Hylh; - try rewrite Hylh; try rewrite spec_w_1; try (ring; fail). - match goal with |- context[ww_sub_c ?x ?y] => - generalize (spec_ww_sub_c x y); case (ww_sub_c x y); try rewrite spec_w_1; - intros z1 Hz2 - end. - simpl in Hz2; rewrite Hz2; repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - rewrite spec_w_0; rewrite Z.mul_0_l; rewrite Z.add_0_l. - generalize Hz2; clear Hz2; unfold interp_carry. - repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - match goal with |- context[ww_add_c ?x ?y] => - generalize (spec_ww_add_c x y); case (ww_add_c x y); try rewrite spec_w_1; - intros z1 Hz2 - end. - simpl in Hz2; rewrite Hz2; repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - rewrite spec_w_2; unfold interp_carry in Hz2. - transitivity (wwB + (1 * wwB + [[z1]])). - ring. - rewrite Hz2; repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - rewrite spec_w_compare; case Z.compare_spec; intros Hylh; - try rewrite Hylh; try rewrite spec_w_1; try (ring; fail). - match goal with |- context[ww_add_c ?x ?y] => - generalize (spec_ww_add_c x y); case (ww_add_c x y); try rewrite spec_w_1; - intros z1 Hz2 - end. - simpl in Hz2; rewrite Hz2; repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - rewrite spec_w_2; unfold interp_carry in Hz2. - transitivity (wwB + (1 * wwB + [[z1]])). - ring. - rewrite Hz2; repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - match goal with |- context[ww_sub_c ?x ?y] => - generalize (spec_ww_sub_c x y); case (ww_sub_c x y); try rewrite spec_w_1; - intros z1 Hz2 - end. - simpl in Hz2; rewrite Hz2; repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - rewrite spec_w_0; rewrite Z.mul_0_l; rewrite Z.add_0_l. - match goal with |- context[(?x - ?y) * (?z - ?t)] => - replace ((x - y) * (z - t)) with ((y - x) * (t - z)); [idtac | ring] - end. - generalize Hz2; clear Hz2; unfold interp_carry. - repeat (rewrite spec_w_sub || rewrite spec_w_mul_c). - repeat rewrite Zmod_small; auto with zarith; try (ring; fail). - Qed. - - Lemma sub_carry : forall xh xl yh yl z, - 0 <= z -> - [|xh|]*[|yl|] + [|xl|]*[|yh|] = wwB + z -> - z < wwB. - Proof. - intros xh xl yh yl z Hle Heq. - destruct (Z_le_gt_dec wwB z);auto with zarith. - generalize (Zmult_lt_b _ _ _ (spec_to_Z xh) (spec_to_Z yl)). - generalize (Zmult_lt_b _ _ _ (spec_to_Z xl) (spec_to_Z yh)). - rewrite <- wwB_wBwB;intros H1 H2. - assert (H3 := wB_pos w_digits). - assert (2*wB <= wwB). - rewrite wwB_wBwB; rewrite Z.pow_2_r; apply Z.mul_le_mono_nonneg;zarith. - omega. - Qed. - - Ltac Spec_ww_to_Z x := - let H:= fresh "H" in - assert (H:= spec_ww_to_Z x). - - Ltac Zmult_lt_b x y := - let H := fresh "H" in - assert (H := Zmult_lt_b _ _ _ (spec_to_Z x) (spec_to_Z y)). - - Lemma spec_ww_karatsuba_c : forall x y, [||ww_karatsuba_c x y||]=[[x]]*[[y]]. - Proof. - intros x y; unfold ww_karatsuba_c;apply spec_double_mul_c. - intros; apply spec_kara_prod; auto. - Qed. - - Lemma spec_ww_mul : forall x y, [[ww_mul x y]] = [[x]]*[[y]] mod wwB. - Proof. - assert (U:= lt_0_wB w_digits). - assert (U1:= lt_0_wwB w_digits). - intros x y; case x; auto; intros xh xl. - case y; auto. - simpl; rewrite Z.mul_0_r; rewrite Zmod_small; auto with zarith. - intros yh yl;simpl. - repeat (rewrite spec_ww_add || rewrite spec_w_W0 || rewrite spec_w_mul_c - || rewrite spec_w_add || rewrite spec_w_mul). - rewrite <- Zplus_mod; auto with zarith. - repeat (rewrite Z.mul_add_distr_r || rewrite Z.mul_add_distr_l). - rewrite <- Zmult_mod_distr_r; auto with zarith. - rewrite <- Z.pow_2_r; rewrite <- wwB_wBwB; auto with zarith. - rewrite Zplus_mod; auto with zarith. - rewrite Zmod_mod; auto with zarith. - rewrite <- Zplus_mod; auto with zarith. - match goal with |- ?X mod _ = _ => - rewrite <- Z_mod_plus with (a := X) (b := [|xh|] * [|yh|]) - end; auto with zarith. - f_equal; auto; rewrite wwB_wBwB; ring. - Qed. - - Lemma spec_ww_square_c : forall x, [||ww_square_c x||] = [[x]]*[[x]]. - Proof. - destruct x as [ |xh xl];simpl;trivial. - case_eq match ww_add_c (w_mul_c xh xl) (w_mul_c xh xl) with - | C0 cc => (w_0, cc) - | C1 cc => (w_1, cc) - end;intros wc cc Heq. - apply (spec_mul_aux xh xl xh xl wc cc);trivial. - generalize Heq (spec_ww_add_c (w_mul_c xh xl) (w_mul_c xh xl));clear Heq. - rewrite spec_w_mul_c;destruct (ww_add_c (w_mul_c xh xl) (w_mul_c xh xl)); - unfold interp_carry;try rewrite Z.mul_1_l;intros Heq Heq';inversion Heq; - rewrite (Z.mul_comm [|xl|]);subst. - rewrite spec_w_0;rewrite Z.mul_0_l;rewrite Z.add_0_l;trivial. - rewrite spec_w_1;rewrite Z.mul_1_l;rewrite <- wwB_wBwB;trivial. - Qed. - - Section DoubleMulAddn1Proof. - - Variable w_mul_add : w -> w -> w -> w * w. - Variable spec_w_mul_add : forall x y r, - let (h,l):= w_mul_add x y r in - [|h|]*wB+[|l|] = [|x|]*[|y|] + [|r|]. - - Lemma spec_double_mul_add_n1 : forall n x y r, - let (h,l) := double_mul_add_n1 w_mul_add n x y r in - [|h|]*double_wB w_digits n + [!n|l!] = [!n|x!]*[|y|]+[|r|]. - Proof. - induction n;intros x y r;trivial. - exact (spec_w_mul_add x y r). - unfold double_mul_add_n1;destruct x as[ |xh xl]; - fold(double_mul_add_n1 w_mul_add). - rewrite spec_w_0;rewrite spec_extend;simpl;trivial. - assert(H:=IHn xl y r);destruct (double_mul_add_n1 w_mul_add n xl y r)as(rl,l). - assert(U:=IHn xh y rl);destruct(double_mul_add_n1 w_mul_add n xh y rl)as(rh,h). - rewrite <- double_wB_wwB. rewrite spec_double_WW;simpl;trivial. - rewrite Z.mul_add_distr_r;rewrite <- Z.add_assoc;rewrite <- H. - rewrite Z.mul_assoc;rewrite Z.add_assoc;rewrite <- Z.mul_add_distr_r. - rewrite U;ring. - Qed. - - End DoubleMulAddn1Proof. - - Lemma spec_w_mul_add : forall x y r, - let (h,l):= w_mul_add x y r in - [|h|]*wB+[|l|] = [|x|]*[|y|] + [|r|]. - Proof. - intros x y r;unfold w_mul_add;assert (H:=spec_w_mul_c x y); - destruct (w_mul_c x y) as [ |h l];simpl;rewrite <- H. - rewrite spec_w_0;trivial. - assert (U:=spec_w_add_c l r);destruct (w_add_c l r) as [lr|lr];unfold - interp_carry in U;try rewrite Z.mul_1_l in H;simpl. - rewrite U;ring. rewrite spec_w_succ. rewrite Zmod_small. - rewrite <- Z.add_assoc;rewrite <- U;ring. - simpl in H;assert (H1:= Zmult_lt_b _ _ _ (spec_to_Z x) (spec_to_Z y)). - rewrite <- H in H1. - assert (H2:=spec_to_Z h);split;zarith. - case H1;clear H1;intro H1;clear H1. - replace (wB ^ 2 - 2 * wB) with ((wB - 2)*wB). 2:ring. - intros H0;assert (U1:= wB_pos w_digits). - assert (H1 := beta_lex _ _ _ _ _ H0 (spec_to_Z l));zarith. - Qed. - -(* End DoubleProof. *) - -End DoubleMul. |