diff options
Diffstat (limited to 'theories/Numbers/Cyclic/DoubleCyclic/DoubleSqrt.v')
| -rw-r--r-- | theories/Numbers/Cyclic/DoubleCyclic/DoubleSqrt.v | 1369 |
1 files changed, 0 insertions, 1369 deletions
diff --git a/theories/Numbers/Cyclic/DoubleCyclic/DoubleSqrt.v b/theories/Numbers/Cyclic/DoubleCyclic/DoubleSqrt.v deleted file mode 100644 index d07ce301..00000000 --- a/theories/Numbers/Cyclic/DoubleCyclic/DoubleSqrt.v +++ /dev/null @@ -1,1369 +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 DoubleSqrt. - Variable w : Type. - Variable w_is_even : w -> bool. - Variable w_compare : w -> w -> comparison. - Variable w_0 : w. - Variable w_1 : w. - Variable w_Bm1 : w. - Variable w_WW : w -> w -> zn2z w. - Variable w_W0 : w -> zn2z w. - Variable w_0W : w -> zn2z w. - Variable w_sub : w -> w -> w. - Variable w_sub_c : w -> w -> carry w. - Variable w_square_c : w -> zn2z w. - Variable w_div21 : w -> w -> w -> w * w. - Variable w_add_mul_div : w -> w -> w -> w. - Variable w_digits : positive. - Variable w_zdigits : w. - Variable ww_zdigits : zn2z w. - Variable w_add_c : w -> w -> carry w. - Variable w_sqrt2 : w -> w -> w * carry w. - Variable w_pred : w -> w. - Variable ww_pred_c : zn2z w -> carry (zn2z w). - Variable ww_pred : zn2z 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_sub_c : zn2z w -> zn2z w -> carry (zn2z w). - Variable ww_add_mul_div : zn2z w -> zn2z w -> zn2z w -> zn2z w. - Variable ww_head0 : zn2z w -> zn2z w. - Variable ww_compare : zn2z w -> zn2z w -> comparison. - Variable low : zn2z w -> w. - - Let wwBm1 := ww_Bm1 w_Bm1. - - Definition ww_is_even x := - match x with - | W0 => true - | WW xh xl => w_is_even xl - end. - - Let w_div21c x y z := - match w_compare x z with - | Eq => - match w_compare y z with - Eq => (C1 w_1, w_0) - | Gt => (C1 w_1, w_sub y z) - | Lt => (C1 w_0, y) - end - | Gt => - let x1 := w_sub x z in - let (q, r) := w_div21 x1 y z in - (C1 q, r) - | Lt => - let (q, r) := w_div21 x y z in - (C0 q, r) - end. - - Let w_div2s x y s := - match x with - C1 x1 => - let x2 := w_sub x1 s in - let (q, r) := w_div21c x2 y s in - match q with - C0 q1 => - if w_is_even q1 then - (C0 (w_add_mul_div (w_pred w_zdigits) w_1 q1), C0 r) - else - (C0 (w_add_mul_div (w_pred w_zdigits) w_1 q1), w_add_c r s) - | C1 q1 => - if w_is_even q1 then - (C1 (w_add_mul_div (w_pred w_zdigits) w_0 q1), C0 r) - else - (C1 (w_add_mul_div (w_pred w_zdigits) w_0 q1), w_add_c r s) - end - | C0 x1 => - let (q, r) := w_div21c x1 y s in - match q with - C0 q1 => - if w_is_even q1 then - (C0 (w_add_mul_div (w_pred w_zdigits) w_0 q1), C0 r) - else - (C0 (w_add_mul_div (w_pred w_zdigits) w_0 q1), w_add_c r s) - | C1 q1 => - if w_is_even q1 then - (C0 (w_add_mul_div (w_pred w_zdigits) w_1 q1), C0 r) - else - (C0 (w_add_mul_div (w_pred w_zdigits) w_1 q1), w_add_c r s) - end - end. - - Definition split x := - match x with - | W0 => (w_0,w_0) - | WW h l => (h,l) - end. - - Definition ww_sqrt2 x y := - let (x1, x2) := split x in - let (y1, y2) := split y in - let ( q, r) := w_sqrt2 x1 x2 in - let (q1, r1) := w_div2s r y1 q in - match q1 with - C0 q1 => - let q2 := w_square_c q1 in - let a := WW q q1 in - match r1 with - C1 r2 => - match ww_sub_c (WW r2 y2) q2 with - C0 r3 => (a, C1 r3) - | C1 r3 => (a, C0 r3) - end - | C0 r2 => - match ww_sub_c (WW r2 y2) q2 with - C0 r3 => (a, C0 r3) - | C1 r3 => - let a2 := ww_add_mul_div (w_0W w_1) a W0 in - match ww_pred_c a2 with - C0 a3 => - (ww_pred a, ww_add_c a3 r3) - | C1 a3 => - (ww_pred a, C0 (ww_add a3 r3)) - end - end - end - | C1 q1 => - let a1 := WW q w_Bm1 in - let a2 := ww_add_mul_div (w_0W w_1) a1 wwBm1 in - (a1, ww_add_c a2 y) - end. - - Definition ww_is_zero x := - match ww_compare W0 x with - Eq => true - | _ => false - end. - - Definition ww_head1 x := - let p := ww_head0 x in - if (ww_is_even p) then p else ww_pred p. - - Definition ww_sqrt x := - if (ww_is_zero x) then W0 - else - let p := ww_head1 x in - match ww_compare p W0 with - | Gt => - match ww_add_mul_div p x W0 with - W0 => W0 - | WW x1 x2 => - let (r, _) := w_sqrt2 x1 x2 in - WW w_0 (w_add_mul_div - (w_sub w_zdigits - (low (ww_add_mul_div (ww_pred ww_zdigits) - W0 p))) w_0 r) - end - | _ => - match x with - W0 => W0 - | WW x1 x2 => WW w_0 (fst (w_sqrt2 x1 x2)) - end - end. - - - 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_w_0 : [|w_0|] = 0. - Variable spec_w_1 : [|w_1|] = 1. - Variable spec_w_Bm1 : [|w_Bm1|] = wB - 1. - Variable spec_w_zdigits : [|w_zdigits|] = Zpos w_digits. - Variable spec_more_than_1_digit: 1 < Zpos w_digits. - - Variable spec_ww_zdigits : [[ww_zdigits]] = Zpos (xO w_digits). - Variable spec_to_Z : forall x, 0 <= [|x|] < wB. - Variable spec_to_w_Z : forall x, 0 <= [[x]] < wwB. - - 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_is_even : forall x, - if w_is_even x then [|x|] mod 2 = 0 else [|x|] mod 2 = 1. - Variable spec_w_compare : forall x y, - w_compare x y = Z.compare [|x|] [|y|]. - Variable spec_w_sub : forall x y, [|w_sub x y|] = ([|x|] - [|y|]) mod wB. - Variable spec_w_square_c : forall x, [[ w_square_c x]] = [|x|] * [|x|]. - Variable spec_w_div21 : forall a1 a2 b, - wB/2 <= [|b|] -> - [|a1|] < [|b|] -> - let (q,r) := w_div21 a1 a2 b in - [|a1|] *wB+ [|a2|] = [|q|] * [|b|] + [|r|] /\ - 0 <= [|r|] < [|b|]. - Variable spec_w_add_mul_div : forall x y p, - [|p|] <= Zpos w_digits -> - [| w_add_mul_div p x y |] = - ([|x|] * (2 ^ [|p|]) + - [|y|] / (Z.pow 2 ((Zpos w_digits) - [|p|]))) mod wB. - Variable spec_ww_add_mul_div : forall x y p, - [[p]] <= Zpos (xO w_digits) -> - [[ ww_add_mul_div p x y ]] = - ([[x]] * (2^ [[p]]) + - [[y]] / (2^ (Zpos (xO w_digits) - [[p]]))) mod wwB. - Variable spec_w_add_c : forall x y, [+|w_add_c x y|] = [|x|] + [|y|]. - Variable spec_ww_add : forall x y, [[ww_add x y]] = ([[x]] + [[y]]) mod wwB. - Variable spec_w_sqrt2 : forall x y, - wB/ 4 <= [|x|] -> - let (s,r) := w_sqrt2 x y in - [[WW x y]] = [|s|] ^ 2 + [+|r|] /\ - [+|r|] <= 2 * [|s|]. - Variable spec_ww_sub_c : forall x y, [-[ww_sub_c x y]] = [[x]] - [[y]]. - Variable spec_ww_pred_c : forall x, [-[ww_pred_c x]] = [[x]] - 1. - Variable spec_pred : forall x, [|w_pred x|] = ([|x|] - 1) mod wB. - Variable spec_ww_pred : forall x, [[ww_pred x]] = ([[x]] - 1) mod wwB. - Variable spec_ww_add_c : forall x y, [+[ww_add_c x y]] = [[x]] + [[y]]. - Variable spec_ww_compare : forall x y, - ww_compare x y = Z.compare [[x]] [[y]]. - Variable spec_ww_head0 : forall x, 0 < [[x]] -> - wwB/ 2 <= 2 ^ [[ww_head0 x]] * [[x]] < wwB. - Variable spec_low: forall x, [|low x|] = [[x]] mod wB. - - Let spec_ww_Bm1 : [[wwBm1]] = wwB - 1. - Proof. refine (spec_ww_Bm1 w_Bm1 w_digits w_to_Z _);auto. Qed. - - Hint Rewrite spec_w_0 spec_w_1 spec_w_WW spec_w_sub - spec_w_add_mul_div spec_ww_Bm1 spec_w_add_c : w_rewrite. - - Lemma spec_ww_is_even : forall x, - if ww_is_even x then [[x]] mod 2 = 0 else [[x]] mod 2 = 1. -clear spec_more_than_1_digit. -intros x; case x; simpl ww_is_even. - reflexivity. - simpl. - intros w1 w2; simpl. - unfold base. - rewrite Zplus_mod; auto with zarith. - rewrite (fun x y => (Zdivide_mod (x * y))); auto with zarith. - rewrite Z.add_0_l; rewrite Zmod_mod; auto with zarith. - apply spec_w_is_even; auto with zarith. - apply Z.divide_mul_r; apply Zpower_divide; auto with zarith. - Qed. - - - Theorem spec_w_div21c : forall a1 a2 b, - wB/2 <= [|b|] -> - let (q,r) := w_div21c a1 a2 b in - [|a1|] * wB + [|a2|] = [+|q|] * [|b|] + [|r|] /\ 0 <= [|r|] < [|b|]. - intros a1 a2 b Hb; unfold w_div21c. - assert (H: 0 < [|b|]); auto with zarith. - assert (U := wB_pos w_digits). - apply Z.lt_le_trans with (2 := Hb); auto with zarith. - apply Z.lt_le_trans with 1; auto with zarith. - apply Zdiv_le_lower_bound; auto with zarith. - rewrite !spec_w_compare. repeat case Z.compare_spec. - intros H1 H2; split. - unfold interp_carry; autorewrite with w_rewrite rm10; auto with zarith. - rewrite H1; rewrite H2; ring. - autorewrite with w_rewrite; auto with zarith. - intros H1 H2; split. - unfold interp_carry; autorewrite with w_rewrite rm10; auto with zarith. - rewrite H2; ring. - destruct (spec_to_Z a2);auto with zarith. - intros H1 H2; split. - unfold interp_carry; autorewrite with w_rewrite rm10; auto with zarith. - rewrite H2; rewrite Zmod_small; auto with zarith. - ring. - destruct (spec_to_Z a2);auto with zarith. - rewrite spec_w_sub; auto with zarith. - destruct (spec_to_Z a2) as [H3 H4];auto with zarith. - rewrite Zmod_small; auto with zarith. - split; auto with zarith. - assert ([|a2|] < 2 * [|b|]); auto with zarith. - apply Z.lt_le_trans with (2 * (wB / 2)); auto with zarith. - rewrite wB_div_2; auto. - intros H1. - match goal with |- context[w_div21 ?y ?z ?t] => - generalize (@spec_w_div21 y z t Hb H1); - case (w_div21 y z t); simpl; autorewrite with w_rewrite; - auto - end. - intros H1. - assert (H2: [|w_sub a1 b|] < [|b|]). - rewrite spec_w_sub; auto with zarith. - rewrite Zmod_small; auto with zarith. - assert ([|a1|] < 2 * [|b|]); auto with zarith. - apply Z.lt_le_trans with (2 * (wB / 2)); auto with zarith. - rewrite wB_div_2; auto. - destruct (spec_to_Z a1);auto with zarith. - destruct (spec_to_Z a1);auto with zarith. - match goal with |- context[w_div21 ?y ?z ?t] => - generalize (@spec_w_div21 y z t Hb H2); - case (w_div21 y z t); autorewrite with w_rewrite; - auto - end. - intros w0 w1; replace [+|C1 w0|] with (wB + [|w0|]). - rewrite Zmod_small; auto with zarith. - intros (H3, H4); split; auto. - rewrite Z.mul_add_distr_r. - rewrite <- Z.add_assoc; rewrite <- H3; ring. - split; auto with zarith. - assert ([|a1|] < 2 * [|b|]); auto with zarith. - apply Z.lt_le_trans with (2 * (wB / 2)); auto with zarith. - rewrite wB_div_2; auto. - destruct (spec_to_Z a1);auto with zarith. - destruct (spec_to_Z a1);auto with zarith. - simpl; case wB; auto. - Qed. - - Theorem C0_id: forall p, [+|C0 p|] = [|p|]. - intros p; simpl; auto. - Qed. - - Theorem add_mult_div_2: forall w, - [|w_add_mul_div (w_pred w_zdigits) w_0 w|] = [|w|] / 2. - intros w1. - assert (Hp: [|w_pred w_zdigits|] = Zpos w_digits - 1). - rewrite spec_pred; rewrite spec_w_zdigits. - rewrite Zmod_small; auto with zarith. - split; auto with zarith. - apply Z.lt_le_trans with (Zpos w_digits); auto with zarith. - unfold base; apply Zpower2_le_lin; auto with zarith. - rewrite spec_w_add_mul_div; auto with zarith. - autorewrite with w_rewrite rm10. - match goal with |- context[?X - ?Y] => - replace (X - Y) with 1 - end. - rewrite Z.pow_1_r; rewrite Zmod_small; auto with zarith. - destruct (spec_to_Z w1) as [H1 H2];auto with zarith. - split; auto with zarith. - apply Zdiv_lt_upper_bound; auto with zarith. - rewrite Hp; ring. - Qed. - - Theorem add_mult_div_2_plus_1: forall w, - [|w_add_mul_div (w_pred w_zdigits) w_1 w|] = - [|w|] / 2 + 2 ^ Zpos (w_digits - 1). - intros w1. - assert (Hp: [|w_pred w_zdigits|] = Zpos w_digits - 1). - rewrite spec_pred; rewrite spec_w_zdigits. - rewrite Zmod_small; auto with zarith. - split; auto with zarith. - apply Z.lt_le_trans with (Zpos w_digits); auto with zarith. - unfold base; apply Zpower2_le_lin; auto with zarith. - autorewrite with w_rewrite rm10; auto with zarith. - match goal with |- context[?X - ?Y] => - replace (X - Y) with 1 - end; rewrite Hp; try ring. - rewrite Pos2Z.inj_sub_max; auto with zarith. - rewrite Z.max_r; auto with zarith. - rewrite Z.pow_1_r; rewrite Zmod_small; auto with zarith. - destruct (spec_to_Z w1) as [H1 H2];auto with zarith. - split; auto with zarith. - unfold base. - match goal with |- _ < _ ^ ?X => - assert (tmp: forall p, 1 + (p - 1) = p); auto with zarith; - rewrite <- (tmp X); clear tmp - end. - rewrite Zpower_exp; try rewrite Z.pow_1_r; auto with zarith. - assert (tmp: forall p, 1 + (p -1) - 1 = p - 1); auto with zarith; - rewrite tmp; clear tmp; auto with zarith. - match goal with |- ?X + ?Y < _ => - assert (Y < X); auto with zarith - end. - apply Zdiv_lt_upper_bound; auto with zarith. - pattern 2 at 2; rewrite <- Z.pow_1_r; rewrite <- Zpower_exp; - auto with zarith. - assert (tmp: forall p, (p - 1) + 1 = p); auto with zarith; - rewrite tmp; clear tmp; auto with zarith. - Qed. - - Theorem add_mult_mult_2: forall w, - [|w_add_mul_div w_1 w w_0|] = 2 * [|w|] mod wB. - intros w1. - autorewrite with w_rewrite rm10; auto with zarith. - rewrite Z.pow_1_r; auto with zarith. - rewrite Z.mul_comm; auto. - Qed. - - Theorem ww_add_mult_mult_2: forall w, - [[ww_add_mul_div (w_0W w_1) w W0]] = 2 * [[w]] mod wwB. - intros w1. - rewrite spec_ww_add_mul_div; auto with zarith. - autorewrite with w_rewrite rm10. - rewrite spec_w_0W; rewrite spec_w_1. - rewrite Z.pow_1_r; auto with zarith. - rewrite Z.mul_comm; auto. - rewrite spec_w_0W; rewrite spec_w_1; auto with zarith. - red; simpl; intros; discriminate. - Qed. - - Theorem ww_add_mult_mult_2_plus_1: forall w, - [[ww_add_mul_div (w_0W w_1) w wwBm1]] = - (2 * [[w]] + 1) mod wwB. - intros w1. - rewrite spec_ww_add_mul_div; auto with zarith. - rewrite spec_w_0W; rewrite spec_w_1; auto with zarith. - rewrite Z.pow_1_r; auto with zarith. - f_equal; auto. - rewrite Z.mul_comm; f_equal; auto. - autorewrite with w_rewrite rm10. - unfold ww_digits, base. - symmetry; apply Zdiv_unique with (r := 2 ^ (Zpos (ww_digits w_digits) - 1) -1); - auto with zarith. - unfold ww_digits; split; auto with zarith. - match goal with |- 0 <= ?X - 1 => - assert (0 < X); auto with zarith - end. - apply Z.pow_pos_nonneg; auto with zarith. - match goal with |- 0 <= ?X - 1 => - assert (0 < X); auto with zarith; red; reflexivity - end. - unfold ww_digits; autorewrite with rm10. - assert (tmp: forall p q r, p + (q - r) = p + q - r); auto with zarith; - rewrite tmp; clear tmp. - assert (tmp: forall p, p + p = 2 * p); auto with zarith; - rewrite tmp; clear tmp. - f_equal; auto. - pattern 2 at 2; rewrite <- Z.pow_1_r; rewrite <- Zpower_exp; - auto with zarith. - assert (tmp: forall p, 1 + (p - 1) = p); auto with zarith; - rewrite tmp; clear tmp; auto. - match goal with |- ?X - 1 >= 0 => - assert (0 < X); auto with zarith; red; reflexivity - end. - rewrite spec_w_0W; rewrite spec_w_1; auto with zarith. - red; simpl; intros; discriminate. - Qed. - - Theorem Zplus_mod_one: forall a1 b1, 0 < b1 -> (a1 + b1) mod b1 = a1 mod b1. - intros a1 b1 H; rewrite Zplus_mod; auto with zarith. - rewrite Z_mod_same; try rewrite Z.add_0_r; auto with zarith. - apply Zmod_mod; auto. - Qed. - - Lemma C1_plus_wB: forall x, [+|C1 x|] = wB + [|x|]. - unfold interp_carry; auto with zarith. - Qed. - - Theorem spec_w_div2s : forall a1 a2 b, - wB/2 <= [|b|] -> [+|a1|] <= 2 * [|b|] -> - let (q,r) := w_div2s a1 a2 b in - [+|a1|] * wB + [|a2|] = [+|q|] * (2 * [|b|]) + [+|r|] /\ 0 <= [+|r|] < 2 * [|b|]. - intros a1 a2 b H. - assert (HH: 0 < [|b|]); auto with zarith. - assert (U := wB_pos w_digits). - apply Z.lt_le_trans with (2 := H); auto with zarith. - apply Z.lt_le_trans with 1; auto with zarith. - apply Zdiv_le_lower_bound; auto with zarith. - unfold w_div2s; case a1; intros w0 H0. - match goal with |- context[w_div21c ?y ?z ?t] => - generalize (@spec_w_div21c y z t H); - case (w_div21c y z t); autorewrite with w_rewrite; - auto - end. - intros c w1; case c. - simpl interp_carry; intros w2 (Hw1, Hw2). - match goal with |- context[w_is_even ?y] => - generalize (spec_w_is_even y); - case (w_is_even y) - end. - repeat rewrite C0_id. - rewrite add_mult_div_2. - intros H1; split; auto with zarith. - rewrite Hw1. - pattern [|w2|] at 1; rewrite (Z_div_mod_eq [|w2|] 2); - auto with zarith. - rewrite H1; ring. - repeat rewrite C0_id. - rewrite add_mult_div_2. - rewrite spec_w_add_c; auto with zarith. - intros H1; split; auto with zarith. - rewrite Hw1. - pattern [|w2|] at 1; rewrite (Z_div_mod_eq [|w2|] 2); - auto with zarith. - rewrite H1; ring. - intros w2; rewrite C1_plus_wB. - intros (Hw1, Hw2). - match goal with |- context[w_is_even ?y] => - generalize (spec_w_is_even y); - case (w_is_even y) - end. - repeat rewrite C0_id. - intros H1; split; auto with zarith. - rewrite Hw1. - pattern [|w2|] at 1; rewrite (Z_div_mod_eq [|w2|] 2); - auto with zarith. - rewrite H1. - repeat rewrite C0_id. - rewrite add_mult_div_2_plus_1; unfold base. - match goal with |- context[_ ^ ?X] => - assert (tmp: forall p, 1 + (p - 1) = p); auto with zarith; - rewrite <- (tmp X); clear tmp; rewrite Zpower_exp; - try rewrite Z.pow_1_r; auto with zarith - end. - rewrite Pos2Z.inj_sub_max; auto with zarith. - rewrite Z.max_r; auto with zarith. - ring. - repeat rewrite C0_id. - rewrite spec_w_add_c; auto with zarith. - intros H1; split; auto with zarith. - rewrite add_mult_div_2_plus_1. - rewrite Hw1. - pattern [|w2|] at 1; rewrite (Z_div_mod_eq [|w2|] 2); - auto with zarith. - rewrite H1. - unfold base. - match goal with |- context[_ ^ ?X] => - assert (tmp: forall p, 1 + (p - 1) = p); auto with zarith; - rewrite <- (tmp X); clear tmp; rewrite Zpower_exp; - try rewrite Z.pow_1_r; auto with zarith - end. - rewrite Pos2Z.inj_sub_max; auto with zarith. - rewrite Z.max_r; auto with zarith. - ring. - repeat rewrite C1_plus_wB in H0. - rewrite C1_plus_wB. - match goal with |- context[w_div21c ?y ?z ?t] => - generalize (@spec_w_div21c y z t H); - case (w_div21c y z t); autorewrite with w_rewrite; - auto - end. - intros c w1; case c. - intros w2 (Hw1, Hw2); rewrite C0_id in Hw1. - rewrite <- Zplus_mod_one in Hw1; auto with zarith. - rewrite Zmod_small in Hw1; auto with zarith. - match goal with |- context[w_is_even ?y] => - generalize (spec_w_is_even y); - case (w_is_even y) - end. - repeat rewrite C0_id. - intros H1; split; auto with zarith. - rewrite add_mult_div_2_plus_1. - replace (wB + [|w0|]) with ([|b|] + ([|w0|] - [|b|] + wB)); - auto with zarith. - rewrite Z.mul_add_distr_r; rewrite <- Z.add_assoc. - rewrite Hw1. - pattern [|w2|] at 1; rewrite (Z_div_mod_eq [|w2|] 2); - auto with zarith. - rewrite H1; unfold base. - match goal with |- context[_ ^ ?X] => - assert (tmp: forall p, 1 + (p - 1) = p); auto with zarith; - rewrite <- (tmp X); clear tmp; rewrite Zpower_exp; - try rewrite Z.pow_1_r; auto with zarith - end. - rewrite Pos2Z.inj_sub_max; auto with zarith. - rewrite Z.max_r; auto with zarith. - ring. - repeat rewrite C0_id. - rewrite add_mult_div_2_plus_1. - rewrite spec_w_add_c; auto with zarith. - intros H1; split; auto with zarith. - replace (wB + [|w0|]) with ([|b|] + ([|w0|] - [|b|] + wB)); - auto with zarith. - rewrite Z.mul_add_distr_r; rewrite <- Z.add_assoc. - rewrite Hw1. - pattern [|w2|] at 1; rewrite (Z_div_mod_eq [|w2|] 2); - auto with zarith. - rewrite H1; unfold base. - match goal with |- context[_ ^ ?X] => - assert (tmp: forall p, 1 + (p - 1) = p); auto with zarith; - rewrite <- (tmp X); clear tmp; rewrite Zpower_exp; - try rewrite Z.pow_1_r; auto with zarith - end. - rewrite Pos2Z.inj_sub_max; auto with zarith. - rewrite Z.max_r; auto with zarith. - ring. - split; auto with zarith. - destruct (spec_to_Z b);auto with zarith. - destruct (spec_to_Z w0);auto with zarith. - destruct (spec_to_Z b);auto with zarith. - destruct (spec_to_Z b);auto with zarith. - intros w2; rewrite C1_plus_wB. - rewrite <- Zplus_mod_one; auto with zarith. - rewrite Zmod_small; auto with zarith. - intros (Hw1, Hw2). - match goal with |- context[w_is_even ?y] => - generalize (spec_w_is_even y); - case (w_is_even y) - end. - repeat (rewrite C0_id || rewrite C1_plus_wB). - intros H1; split; auto with zarith. - rewrite add_mult_div_2. - replace (wB + [|w0|]) with ([|b|] + ([|w0|] - [|b|] + wB)); - auto with zarith. - rewrite Z.mul_add_distr_r; rewrite <- Z.add_assoc. - rewrite Hw1. - pattern [|w2|] at 1; rewrite (Z_div_mod_eq [|w2|] 2); - auto with zarith. - rewrite H1; ring. - repeat (rewrite C0_id || rewrite C1_plus_wB). - rewrite spec_w_add_c; auto with zarith. - intros H1; split; auto with zarith. - rewrite add_mult_div_2. - replace (wB + [|w0|]) with ([|b|] + ([|w0|] - [|b|] + wB)); - auto with zarith. - rewrite Z.mul_add_distr_r; rewrite <- Z.add_assoc. - rewrite Hw1. - pattern [|w2|] at 1; rewrite (Z_div_mod_eq [|w2|] 2); - auto with zarith. - rewrite H1; ring. - split; auto with zarith. - destruct (spec_to_Z b);auto with zarith. - destruct (spec_to_Z w0);auto with zarith. - destruct (spec_to_Z b);auto with zarith. - destruct (spec_to_Z b);auto with zarith. - Qed. - - Theorem wB_div_4: 4 * (wB / 4) = wB. - Proof. - unfold base. - assert (2 ^ Zpos w_digits = - 4 * (2 ^ (Zpos w_digits - 2))). - change 4 with (2 ^ 2). - rewrite <- Zpower_exp; auto with zarith. - f_equal; auto with zarith. - rewrite H. - rewrite (fun x => (Z.mul_comm 4 (2 ^x))). - rewrite Z_div_mult; auto with zarith. - Qed. - - Theorem Zsquare_mult: forall p, p ^ 2 = p * p. - intros p; change 2 with (1 + 1); rewrite Zpower_exp; - try rewrite Z.pow_1_r; auto with zarith. - Qed. - - Theorem Zsquare_pos: forall p, 0 <= p ^ 2. - intros p; case (Z.le_gt_cases 0 p); intros H1. - rewrite Zsquare_mult; apply Z.mul_nonneg_nonneg; auto with zarith. - rewrite Zsquare_mult; replace (p * p) with ((- p) * (- p)); try ring. - apply Z.mul_nonneg_nonneg; auto with zarith. - Qed. - - Lemma spec_split: forall x, - [|fst (split x)|] * wB + [|snd (split x)|] = [[x]]. - intros x; case x; simpl; autorewrite with w_rewrite; - auto with zarith. - Qed. - - Theorem mult_wwB: forall x y, [|x|] * [|y|] < wwB. - Proof. - intros x y; rewrite wwB_wBwB; rewrite Z.pow_2_r. - generalize (spec_to_Z x); intros U. - generalize (spec_to_Z y); intros U1. - apply Z.le_lt_trans with ((wB -1 ) * (wB - 1)); auto with zarith. - apply Z.mul_le_mono_nonneg; auto with zarith. - rewrite ?Z.mul_sub_distr_l, ?Z.mul_sub_distr_r; auto with zarith. - Qed. - Hint Resolve mult_wwB. - - Lemma spec_ww_sqrt2 : forall x y, - wwB/ 4 <= [[x]] -> - let (s,r) := ww_sqrt2 x y in - [||WW x y||] = [[s]] ^ 2 + [+[r]] /\ - [+[r]] <= 2 * [[s]]. - intros x y H; unfold ww_sqrt2. - repeat match goal with |- context[split ?x] => - generalize (spec_split x); case (split x) - end; simpl @fst; simpl @snd. - intros w0 w1 Hw0 w2 w3 Hw1. - assert (U: wB/4 <= [|w2|]). - case (Z.le_gt_cases (wB / 4) [|w2|]); auto; intros H1. - contradict H; apply Z.lt_nge. - rewrite wwB_wBwB; rewrite Z.pow_2_r. - pattern wB at 1; rewrite <- wB_div_4; rewrite <- Z.mul_assoc; - rewrite Z.mul_comm. - rewrite Z_div_mult; auto with zarith. - rewrite <- Hw1. - match goal with |- _ < ?X => - pattern X; rewrite <- Z.add_0_r; apply beta_lex_inv; - auto with zarith - end. - destruct (spec_to_Z w3);auto with zarith. - generalize (@spec_w_sqrt2 w2 w3 U); case (w_sqrt2 w2 w3). - intros w4 c (H1, H2). - assert (U1: wB/2 <= [|w4|]). - case (Z.le_gt_cases (wB/2) [|w4|]); auto with zarith. - intros U1. - assert (U2 : [|w4|] <= wB/2 -1); auto with zarith. - assert (U3 : [|w4|] ^ 2 <= wB/4 * wB - wB + 1); auto with zarith. - match goal with |- ?X ^ 2 <= ?Y => - rewrite Zsquare_mult; - replace Y with ((wB/2 - 1) * (wB/2 -1)) - end. - apply Z.mul_le_mono_nonneg; auto with zarith. - destruct (spec_to_Z w4);auto with zarith. - destruct (spec_to_Z w4);auto with zarith. - pattern wB at 4 5; rewrite <- wB_div_2. - rewrite Z.mul_assoc. - replace ((wB / 4) * 2) with (wB / 2). - ring. - pattern wB at 1; rewrite <- wB_div_4. - change 4 with (2 * 2). - rewrite <- Z.mul_assoc; rewrite (Z.mul_comm 2). - rewrite Z_div_mult; try ring; auto with zarith. - assert (U4 : [+|c|] <= wB -2); auto with zarith. - apply Z.le_trans with (1 := H2). - match goal with |- ?X <= ?Y => - replace Y with (2 * (wB/ 2 - 1)); auto with zarith - end. - pattern wB at 2; rewrite <- wB_div_2; auto with zarith. - match type of H1 with ?X = _ => - assert (U5: X < wB / 4 * wB) - end. - rewrite H1; auto with zarith. - contradict U; apply Z.lt_nge. - apply Z.mul_lt_mono_pos_r with wB; auto with zarith. - destruct (spec_to_Z w4);auto with zarith. - apply Z.le_lt_trans with (2 := U5). - unfold ww_to_Z, zn2z_to_Z. - destruct (spec_to_Z w3);auto with zarith. - generalize (@spec_w_div2s c w0 w4 U1 H2). - case (w_div2s c w0 w4). - intros c0; case c0; intros w5; - repeat (rewrite C0_id || rewrite C1_plus_wB). - intros c1; case c1; intros w6; - repeat (rewrite C0_id || rewrite C1_plus_wB). - intros (H3, H4). - match goal with |- context [ww_sub_c ?y ?z] => - generalize (spec_ww_sub_c y z); case (ww_sub_c y z) - end. - intros z; change [-[C0 z]] with ([[z]]). - change [+[C0 z]] with ([[z]]). - intros H5; rewrite spec_w_square_c in H5; - auto. - split. - unfold zn2z_to_Z; rewrite <- Hw1. - unfold ww_to_Z, zn2z_to_Z in H1. rewrite H1. - rewrite <- Hw0. - match goal with |- (?X ^2 + ?Y) * wwB + (?Z * wB + ?T) = ?U => - transitivity ((X * wB) ^ 2 + (Y * wB + Z) * wB + T) - end. - repeat rewrite Zsquare_mult. - rewrite wwB_wBwB; ring. - rewrite H3. - rewrite H5. - unfold ww_to_Z, zn2z_to_Z. - repeat rewrite Zsquare_mult; ring. - rewrite H5. - unfold ww_to_Z, zn2z_to_Z. - match goal with |- ?X - ?Y * ?Y <= _ => - assert (V := Zsquare_pos Y); - rewrite Zsquare_mult in V; - apply Z.le_trans with X; auto with zarith; - clear V - end. - match goal with |- ?X * wB + ?Y <= 2 * (?Z * wB + ?T) => - apply Z.le_trans with ((2 * Z - 1) * wB + wB); auto with zarith - end. - destruct (spec_to_Z w1);auto with zarith. - match goal with |- ?X <= _ => - replace X with (2 * [|w4|] * wB); auto with zarith - end. - rewrite Z.mul_add_distr_l; rewrite Z.mul_assoc. - destruct (spec_to_Z w5); auto with zarith. - ring. - intros z; replace [-[C1 z]] with (- wwB + [[z]]). - 2: simpl; case wwB; auto with zarith. - intros H5; rewrite spec_w_square_c in H5; - auto. - match goal with |- context [ww_pred_c ?y] => - generalize (spec_ww_pred_c y); case (ww_pred_c y) - end. - intros z1; change [-[C0 z1]] with ([[z1]]). - rewrite ww_add_mult_mult_2. - rewrite spec_ww_add_c. - rewrite spec_ww_pred. - rewrite <- Zmod_unique with (q := 1) (r := -wwB + 2 * [[WW w4 w5]]); - auto with zarith. - intros Hz1; rewrite Zmod_small; auto with zarith. - match type of H5 with -?X + ?Y = ?Z => - assert (V: Y = Z + X); - try (rewrite <- H5; ring) - end. - split. - unfold zn2z_to_Z; rewrite <- Hw1. - unfold ww_to_Z, zn2z_to_Z in H1; rewrite H1. - rewrite <- Hw0. - match goal with |- (?X ^2 + ?Y) * wwB + (?Z * wB + ?T) = ?U => - transitivity ((X * wB) ^ 2 + (Y * wB + Z) * wB + T) - end. - repeat rewrite Zsquare_mult. - rewrite wwB_wBwB; ring. - rewrite H3. - rewrite V. - rewrite Hz1. - unfold ww_to_Z; simpl zn2z_to_Z. - repeat rewrite Zsquare_mult; ring. - rewrite Hz1. - destruct (spec_ww_to_Z w_digits w_to_Z spec_to_Z z);auto with zarith. - assert (V1 := spec_ww_to_Z w_digits w_to_Z spec_to_Z (WW w4 w5)). - assert (0 < [[WW w4 w5]]); auto with zarith. - apply Z.lt_le_trans with (wB/ 2 * wB + 0); auto with zarith. - autorewrite with rm10; apply Z.mul_pos_pos; auto with zarith. - apply Z.mul_lt_mono_pos_r with 2; auto with zarith. - autorewrite with rm10. - rewrite Z.mul_comm; rewrite wB_div_2; auto with zarith. - case (spec_to_Z w5);auto with zarith. - case (spec_to_Z w5);auto with zarith. - simpl. - assert (V2 := spec_to_Z w5);auto with zarith. - assert (V1 := spec_ww_to_Z w_digits w_to_Z spec_to_Z (WW w4 w5)); auto with zarith. - split; auto with zarith. - assert (wwB <= 2 * [[WW w4 w5]]); auto with zarith. - apply Z.le_trans with (2 * ([|w4|] * wB)). - rewrite wwB_wBwB; rewrite Z.pow_2_r. - rewrite Z.mul_assoc; apply Z.mul_le_mono_nonneg_r; auto with zarith. - assert (V2 := spec_to_Z w5);auto with zarith. - rewrite <- wB_div_2; auto with zarith. - simpl ww_to_Z; assert (V2 := spec_to_Z w5);auto with zarith. - assert (V1 := spec_ww_to_Z w_digits w_to_Z spec_to_Z (WW w4 w5)); auto with zarith. - intros z1; change [-[C1 z1]] with (-wwB + [[z1]]). - match goal with |- context[([+[C0 ?z]])] => - change [+[C0 z]] with ([[z]]) - end. - rewrite spec_ww_add; auto with zarith. - rewrite spec_ww_pred; auto with zarith. - rewrite ww_add_mult_mult_2. - rename V1 into VV1. - assert (VV2: 0 < [[WW w4 w5]]); auto with zarith. - apply Z.lt_le_trans with (wB/ 2 * wB + 0); auto with zarith. - autorewrite with rm10; apply Z.mul_pos_pos; auto with zarith. - apply Z.mul_lt_mono_pos_r with 2; auto with zarith. - autorewrite with rm10. - rewrite Z.mul_comm; rewrite wB_div_2; auto with zarith. - assert (VV3 := spec_to_Z w5);auto with zarith. - assert (VV3 := spec_to_Z w5);auto with zarith. - simpl. - assert (VV3 := spec_to_Z w5);auto with zarith. - assert (VV3: wwB <= 2 * [[WW w4 w5]]); auto with zarith. - apply Z.le_trans with (2 * ([|w4|] * wB)). - rewrite wwB_wBwB; rewrite Z.pow_2_r. - rewrite Z.mul_assoc; apply Z.mul_le_mono_nonneg_r; auto with zarith. - case (spec_to_Z w5);auto with zarith. - rewrite <- wB_div_2; auto with zarith. - simpl ww_to_Z; assert (V4 := spec_to_Z w5);auto with zarith. - rewrite <- Zmod_unique with (q := 1) (r := -wwB + 2 * [[WW w4 w5]]); - auto with zarith. - intros Hz1; rewrite Zmod_small; auto with zarith. - match type of H5 with -?X + ?Y = ?Z => - assert (V: Y = Z + X); - try (rewrite <- H5; ring) - end. - match type of Hz1 with -?X + ?Y = -?X + ?Z - 1 => - assert (V1: Y = Z - 1); - [replace (Z - 1) with (X + (-X + Z -1)); - [rewrite <- Hz1 | idtac]; ring - | idtac] - end. - rewrite <- Zmod_unique with (q := 1) (r := -wwB + [[z1]] + [[z]]); - auto with zarith. - unfold zn2z_to_Z; rewrite <- Hw1. - unfold ww_to_Z, zn2z_to_Z in H1; rewrite H1. - rewrite <- Hw0. - split. - match goal with |- (?X ^2 + ?Y) * wwB + (?Z * wB + ?T) = ?U => - transitivity ((X * wB) ^ 2 + (Y * wB + Z) * wB + T) - end. - repeat rewrite Zsquare_mult. - rewrite wwB_wBwB; ring. - rewrite H3. - rewrite V. - rewrite Hz1. - unfold ww_to_Z; simpl zn2z_to_Z. - repeat rewrite Zsquare_mult; ring. - assert (V2 := spec_ww_to_Z w_digits w_to_Z spec_to_Z z);auto with zarith. - assert (V2 := spec_ww_to_Z w_digits w_to_Z spec_to_Z z);auto with zarith. - assert (V3 := spec_ww_to_Z w_digits w_to_Z spec_to_Z z1);auto with zarith. - split; auto with zarith. - rewrite (Z.add_comm (-wwB)); rewrite <- Z.add_assoc. - rewrite H5. - match goal with |- 0 <= ?X + (?Y - ?Z) => - apply Z.le_trans with (X - Z); auto with zarith - end. - 2: generalize (spec_ww_to_Z w_digits w_to_Z spec_to_Z (WW w6 w1)); unfold ww_to_Z; auto with zarith. - rewrite V1. - match goal with |- 0 <= ?X - 1 - ?Y => - assert (Y < X); auto with zarith - end. - apply Z.lt_le_trans with wwB; auto with zarith. - intros (H3, H4). - match goal with |- context [ww_sub_c ?y ?z] => - generalize (spec_ww_sub_c y z); case (ww_sub_c y z) - end. - intros z; change [-[C0 z]] with ([[z]]). - match goal with |- context[([+[C1 ?z]])] => - replace [+[C1 z]] with (wwB + [[z]]) - end. - 2: simpl; case wwB; auto. - intros H5; rewrite spec_w_square_c in H5; - auto. - split. - change ([||WW x y||]) with ([[x]] * wwB + [[y]]). - rewrite <- Hw1. - unfold ww_to_Z, zn2z_to_Z in H1; rewrite H1. - rewrite <- Hw0. - match goal with |- (?X ^2 + ?Y) * wwB + (?Z * wB + ?T) = ?U => - transitivity ((X * wB) ^ 2 + (Y * wB + Z) * wB + T) - end. - repeat rewrite Zsquare_mult. - rewrite wwB_wBwB; ring. - rewrite H3. - rewrite H5. - unfold ww_to_Z; simpl zn2z_to_Z. - rewrite wwB_wBwB. - repeat rewrite Zsquare_mult; ring. - simpl ww_to_Z. - rewrite H5. - simpl ww_to_Z. - rewrite wwB_wBwB; rewrite Z.pow_2_r. - match goal with |- ?X * ?Y + (?Z * ?Y + ?T - ?U) <= _ => - apply Z.le_trans with (X * Y + (Z * Y + T - 0)); - auto with zarith - end. - assert (V := Zsquare_pos [|w5|]); - rewrite Zsquare_mult in V; auto with zarith. - autorewrite with rm10. - match goal with |- _ <= 2 * (?U * ?V + ?W) => - apply Z.le_trans with (2 * U * V + 0); - auto with zarith - end. - match goal with |- ?X * ?Y + (?Z * ?Y + ?T) <= _ => - replace (X * Y + (Z * Y + T)) with ((X + Z) * Y + T); - try ring - end. - apply Z.lt_le_incl; apply beta_lex_inv; auto with zarith. - destruct (spec_to_Z w1);auto with zarith. - destruct (spec_to_Z w5);auto with zarith. - rewrite Z.mul_add_distr_l; auto with zarith. - rewrite Z.mul_assoc; auto with zarith. - intros z; replace [-[C1 z]] with (- wwB + [[z]]). - 2: simpl; case wwB; auto with zarith. - intros H5; rewrite spec_w_square_c in H5; - auto. - match goal with |- context[([+[C0 ?z]])] => - change [+[C0 z]] with ([[z]]) - end. - match type of H5 with -?X + ?Y = ?Z => - assert (V: Y = Z + X); - try (rewrite <- H5; ring) - end. - change ([||WW x y||]) with ([[x]] * wwB + [[y]]). - simpl ww_to_Z. - rewrite <- Hw1. - simpl ww_to_Z in H1; rewrite H1. - rewrite <- Hw0. - split. - match goal with |- (?X ^2 + ?Y) * wwB + (?Z * wB + ?T) = ?U => - transitivity ((X * wB) ^ 2 + (Y * wB + Z) * wB + T) - end. - repeat rewrite Zsquare_mult. - rewrite wwB_wBwB; ring. - rewrite H3. - rewrite V. - simpl ww_to_Z. - rewrite wwB_wBwB. - repeat rewrite Zsquare_mult; ring. - rewrite V. - simpl ww_to_Z. - rewrite wwB_wBwB; rewrite Z.pow_2_r. - match goal with |- (?Z * ?Y + ?T - ?U) + ?X * ?Y <= _ => - apply Z.le_trans with ((Z * Y + T - 0) + X * Y); - auto with zarith - end. - assert (V1 := Zsquare_pos [|w5|]); - rewrite Zsquare_mult in V1; auto with zarith. - autorewrite with rm10. - match goal with |- _ <= 2 * (?U * ?V + ?W) => - apply Z.le_trans with (2 * U * V + 0); - auto with zarith - end. - match goal with |- (?Z * ?Y + ?T) + ?X * ?Y <= _ => - replace ((Z * Y + T) + X * Y) with ((X + Z) * Y + T); - try ring - end. - apply Z.lt_le_incl; apply beta_lex_inv; auto with zarith. - destruct (spec_to_Z w1);auto with zarith. - destruct (spec_to_Z w5);auto with zarith. - rewrite Z.mul_add_distr_l; auto with zarith. - rewrite Z.mul_assoc; auto with zarith. - Z.le_elim H2. - intros c1 (H3, H4). - match type of H3 with ?X = ?Y => absurd (X < Y) end. - apply Z.le_ngt; rewrite <- H3; auto with zarith. - rewrite Z.mul_add_distr_r. - apply Z.lt_le_trans with ((2 * [|w4|]) * wB + 0); - auto with zarith. - apply beta_lex_inv; auto with zarith. - destruct (spec_to_Z w0);auto with zarith. - assert (V1 := spec_to_Z w5);auto with zarith. - rewrite (Z.mul_comm wB); auto with zarith. - assert (0 <= [|w5|] * (2 * [|w4|])); auto with zarith. - intros c1 (H3, H4); rewrite H2 in H3. - match type of H3 with ?X + ?Y = (?Z + ?T) * ?U + ?V => - assert (VV: (Y = (T * U) + V)); - [replace Y with ((X + Y) - X); - [rewrite H3; ring | ring] | idtac] - end. - assert (V1 := spec_to_Z w0);auto with zarith. - assert (V2 := spec_to_Z w5);auto with zarith. - case V2; intros V3 _. - Z.le_elim V3; auto with zarith. - match type of VV with ?X = ?Y => absurd (X < Y) end. - apply Z.le_ngt; rewrite <- VV; auto with zarith. - apply Z.lt_le_trans with wB; auto with zarith. - match goal with |- _ <= ?X + _ => - apply Z.le_trans with X; auto with zarith - end. - match goal with |- _ <= _ * ?X => - apply Z.le_trans with (1 * X); auto with zarith - end. - autorewrite with rm10. - rewrite <- wB_div_2; apply Z.mul_le_mono_nonneg_l; auto with zarith. - rewrite <- V3 in VV; generalize VV; autorewrite with rm10; - clear VV; intros VV. - rewrite spec_ww_add_c; auto with zarith. - rewrite ww_add_mult_mult_2_plus_1. - match goal with |- context[?X mod wwB] => - rewrite <- Zmod_unique with (q := 1) (r := -wwB + X) - end; auto with zarith. - simpl ww_to_Z. - rewrite spec_w_Bm1; auto with zarith. - split. - change ([||WW x y||]) with ([[x]] * wwB + [[y]]). - rewrite <- Hw1. - simpl ww_to_Z in H1; rewrite H1. - rewrite <- Hw0. - match goal with |- (?X ^2 + ?Y) * wwB + (?Z * wB + ?T) = ?U => - transitivity ((X * wB) ^ 2 + (Y * wB + Z) * wB + T) - end. - repeat rewrite Zsquare_mult. - rewrite wwB_wBwB; ring. - rewrite H2. - rewrite wwB_wBwB. - repeat rewrite Zsquare_mult; ring. - assert (V4 := spec_ww_to_Z w_digits w_to_Z spec_to_Z y);auto with zarith. - assert (V4 := spec_ww_to_Z w_digits w_to_Z spec_to_Z y);auto with zarith. - simpl ww_to_Z; unfold ww_to_Z. - rewrite spec_w_Bm1; auto with zarith. - split. - rewrite wwB_wBwB; rewrite Z.pow_2_r. - match goal with |- _ <= -?X + (2 * (?Z * ?T + ?U) + ?V) => - assert (X <= 2 * Z * T); auto with zarith - end. - apply Z.mul_le_mono_nonneg_r; auto with zarith. - rewrite <- wB_div_2; apply Z.mul_le_mono_nonneg_l; auto with zarith. - rewrite Z.mul_add_distr_l; auto with zarith. - rewrite Z.mul_assoc; auto with zarith. - match goal with |- _ + ?X < _ => - replace X with ((2 * (([|w4|]) + 1) * wB) - 1); try ring - end. - assert (2 * ([|w4|] + 1) * wB <= 2 * wwB); auto with zarith. - rewrite <- Z.mul_assoc; apply Z.mul_le_mono_nonneg_l; auto with zarith. - rewrite wwB_wBwB; rewrite Z.pow_2_r. - apply Z.mul_le_mono_nonneg_r; auto with zarith. - case (spec_to_Z w4);auto with zarith. -Qed. - - Lemma spec_ww_is_zero: forall x, - if ww_is_zero x then [[x]] = 0 else 0 < [[x]]. - intro x; unfold ww_is_zero. - rewrite spec_ww_compare. case Z.compare_spec; - auto with zarith. - simpl ww_to_Z. - assert (V4 := spec_ww_to_Z w_digits w_to_Z spec_to_Z x);auto with zarith. - Qed. - - Lemma wwB_4_2: 2 * (wwB / 4) = wwB/ 2. - pattern wwB at 1; rewrite wwB_wBwB; rewrite Z.pow_2_r. - rewrite <- wB_div_2. - match goal with |- context[(2 * ?X) * (2 * ?Z)] => - replace ((2 * X) * (2 * Z)) with ((X * Z) * 4); try ring - end. - rewrite Z_div_mult; auto with zarith. - rewrite Z.mul_assoc; rewrite wB_div_2. - rewrite wwB_div_2; ring. - Qed. - - - Lemma spec_ww_head1 - : forall x : zn2z w, - (ww_is_even (ww_head1 x) = true) /\ - (0 < [[x]] -> wwB / 4 <= 2 ^ [[ww_head1 x]] * [[x]] < wwB). - assert (U := wB_pos w_digits). - intros x; unfold ww_head1. - generalize (spec_ww_is_even (ww_head0 x)); case_eq (ww_is_even (ww_head0 x)). - intros HH H1; rewrite HH; split; auto. - intros H2. - generalize (spec_ww_head0 x H2); case (ww_head0 x); autorewrite with rm10. - intros (H3, H4); split; auto with zarith. - apply Z.le_trans with (2 := H3). - apply Zdiv_le_compat_l; auto with zarith. - intros xh xl (H3, H4); split; auto with zarith. - apply Z.le_trans with (2 := H3). - apply Zdiv_le_compat_l; auto with zarith. - intros H1. - case (spec_to_w_Z (ww_head0 x)); intros Hv1 Hv2. - assert (Hp0: 0 < [[ww_head0 x]]). - generalize (spec_ww_is_even (ww_head0 x)); rewrite H1. - generalize Hv1; case [[ww_head0 x]]. - rewrite Zmod_small; auto with zarith. - intros; assert (0 < Zpos p); auto with zarith. - red; simpl; auto. - intros p H2; case H2; auto. - assert (Hp: [[ww_pred (ww_head0 x)]] = [[ww_head0 x]] - 1). - rewrite spec_ww_pred. - rewrite Zmod_small; auto with zarith. - intros H2; split. - generalize (spec_ww_is_even (ww_pred (ww_head0 x))); - case ww_is_even; auto. - rewrite Hp. - rewrite Zminus_mod; auto with zarith. - rewrite H2; repeat rewrite Zmod_small; auto with zarith. - intros H3; rewrite Hp. - case (spec_ww_head0 x); auto; intros Hv3 Hv4. - assert (Hu: forall u, 0 < u -> 2 * 2 ^ (u - 1) = 2 ^u). - intros u Hu. - pattern 2 at 1; rewrite <- Z.pow_1_r. - rewrite <- Zpower_exp; auto with zarith. - ring_simplify (1 + (u - 1)); auto with zarith. - split; auto with zarith. - apply Z.mul_le_mono_pos_r with 2; auto with zarith. - repeat rewrite (fun x => Z.mul_comm x 2). - rewrite wwB_4_2. - rewrite Z.mul_assoc; rewrite Hu; auto with zarith. - apply Z.le_lt_trans with (2 * 2 ^ ([[ww_head0 x]] - 1) * [[x]]); auto with zarith; - rewrite Hu; auto with zarith. - apply Z.mul_le_mono_nonneg_r; auto with zarith. - apply Zpower_le_monotone; auto with zarith. - Qed. - - Theorem wwB_4_wB_4: wwB / 4 = wB / 4 * wB. - Proof. - symmetry; apply Zdiv_unique with 0; auto with zarith. - rewrite Z.mul_assoc; rewrite wB_div_4; auto with zarith. - rewrite wwB_wBwB; ring. - Qed. - - Lemma spec_ww_sqrt : forall x, - [[ww_sqrt x]] ^ 2 <= [[x]] < ([[ww_sqrt x]] + 1) ^ 2. - assert (U := wB_pos w_digits). - intro x; unfold ww_sqrt. - generalize (spec_ww_is_zero x); case (ww_is_zero x). - simpl ww_to_Z; simpl Z.pow; unfold Z.pow_pos; simpl; - auto with zarith. - intros H1. - rewrite spec_ww_compare. case Z.compare_spec; - simpl ww_to_Z; autorewrite with rm10. - generalize H1; case x. - intros HH; contradict HH; simpl ww_to_Z; auto with zarith. - intros w0 w1; simpl ww_to_Z; autorewrite with w_rewrite rm10. - intros H2; case (spec_ww_head1 (WW w0 w1)); intros H3 H4 H5. - generalize (H4 H2); clear H4; rewrite H5; clear H5; autorewrite with rm10. - intros (H4, H5). - assert (V: wB/4 <= [|w0|]). - apply beta_lex with 0 [|w1|] wB; auto with zarith; autorewrite with rm10. - rewrite <- wwB_4_wB_4; auto. - generalize (@spec_w_sqrt2 w0 w1 V);auto with zarith. - case (w_sqrt2 w0 w1); intros w2 c. - simpl ww_to_Z; simpl @fst. - case c; unfold interp_carry; autorewrite with rm10. - intros w3 (H6, H7); rewrite H6. - assert (V1 := spec_to_Z w3);auto with zarith. - split; auto with zarith. - apply Z.le_lt_trans with ([|w2|] ^2 + 2 * [|w2|]); auto with zarith. - match goal with |- ?X < ?Z => - replace Z with (X + 1); auto with zarith - end. - repeat rewrite Zsquare_mult; ring. - intros w3 (H6, H7); rewrite H6. - assert (V1 := spec_to_Z w3);auto with zarith. - split; auto with zarith. - apply Z.le_lt_trans with ([|w2|] ^2 + 2 * [|w2|]); auto with zarith. - match goal with |- ?X < ?Z => - replace Z with (X + 1); auto with zarith - end. - repeat rewrite Zsquare_mult; ring. - intros HH; case (spec_to_w_Z (ww_head1 x)); auto with zarith. - intros Hv1. - case (spec_ww_head1 x); intros Hp1 Hp2. - generalize (Hp2 H1); clear Hp2; intros Hp2. - assert (Hv2: [[ww_head1 x]] <= Zpos (xO w_digits)). - case (Z.le_gt_cases (Zpos (xO w_digits)) [[ww_head1 x]]); auto with zarith; intros HH1. - case Hp2; intros _ HH2; contradict HH2. - apply Z.le_ngt; unfold base. - apply Z.le_trans with (2 ^ [[ww_head1 x]]). - apply Zpower_le_monotone; auto with zarith. - pattern (2 ^ [[ww_head1 x]]) at 1; - rewrite <- (Z.mul_1_r (2 ^ [[ww_head1 x]])). - apply Z.mul_le_mono_nonneg_l; auto with zarith. - generalize (spec_ww_add_mul_div x W0 (ww_head1 x) Hv2); - case ww_add_mul_div. - simpl ww_to_Z; autorewrite with w_rewrite rm10. - rewrite Zmod_small; auto with zarith. - intros H2. symmetry in H2. rewrite Z.mul_eq_0 in H2. destruct H2 as [H2|H2]. - rewrite H2; unfold Z.pow, Z.pow_pos; simpl; auto with zarith. - match type of H2 with ?X = ?Y => - absurd (Y < X); try (rewrite H2; auto with zarith; fail) - end. - apply Z.pow_pos_nonneg; auto with zarith. - split; auto with zarith. - case Hp2; intros _ tmp; apply Z.le_lt_trans with (2 := tmp); - clear tmp. - rewrite Z.mul_comm; apply Z.mul_le_mono_nonneg_r; auto with zarith. - assert (Hv0: [[ww_head1 x]] = 2 * ([[ww_head1 x]]/2)). - pattern [[ww_head1 x]] at 1; rewrite (Z_div_mod_eq [[ww_head1 x]] 2); - auto with zarith. - generalize (spec_ww_is_even (ww_head1 x)); rewrite Hp1; - intros tmp; rewrite tmp; rewrite Z.add_0_r; auto. - intros w0 w1; autorewrite with w_rewrite rm10. - rewrite Zmod_small; auto with zarith. - 2: rewrite Z.mul_comm; auto with zarith. - intros H2. - assert (V: wB/4 <= [|w0|]). - apply beta_lex with 0 [|w1|] wB; auto with zarith; autorewrite with rm10. - simpl ww_to_Z in H2; rewrite H2. - rewrite <- wwB_4_wB_4; auto with zarith. - rewrite Z.mul_comm; auto with zarith. - assert (V1 := spec_to_Z w1);auto with zarith. - generalize (@spec_w_sqrt2 w0 w1 V);auto with zarith. - case (w_sqrt2 w0 w1); intros w2 c. - case (spec_to_Z w2); intros HH1 HH2. - simpl ww_to_Z; simpl @fst. - assert (Hv3: [[ww_pred ww_zdigits]] - = Zpos (xO w_digits) - 1). - rewrite spec_ww_pred; rewrite spec_ww_zdigits. - rewrite Zmod_small; auto with zarith. - split; auto with zarith. - apply Z.lt_le_trans with (Zpos (xO w_digits)); auto with zarith. - unfold base; apply Zpower2_le_lin; auto with zarith. - assert (Hv4: [[ww_head1 x]]/2 < wB). - apply Z.le_lt_trans with (Zpos w_digits). - apply Z.mul_le_mono_pos_r with 2; auto with zarith. - repeat rewrite (fun x => Z.mul_comm x 2). - rewrite <- Hv0; rewrite <- Pos2Z.inj_xO; auto. - unfold base; apply Zpower2_lt_lin; auto with zarith. - assert (Hv5: [[(ww_add_mul_div (ww_pred ww_zdigits) W0 (ww_head1 x))]] - = [[ww_head1 x]]/2). - rewrite spec_ww_add_mul_div. - simpl ww_to_Z; autorewrite with rm10. - rewrite Hv3. - ring_simplify (Zpos (xO w_digits) - (Zpos (xO w_digits) - 1)). - rewrite Z.pow_1_r. - rewrite Zmod_small; auto with zarith. - split; auto with zarith. - apply Z.lt_le_trans with (1 := Hv4); auto with zarith. - unfold base; apply Zpower_le_monotone; auto with zarith. - split; unfold ww_digits; try rewrite Pos2Z.inj_xO; auto with zarith. - rewrite Hv3; auto with zarith. - assert (Hv6: [|low(ww_add_mul_div (ww_pred ww_zdigits) W0 (ww_head1 x))|] - = [[ww_head1 x]]/2). - rewrite spec_low. - rewrite Hv5; rewrite Zmod_small; auto with zarith. - rewrite spec_w_add_mul_div; auto with zarith. - rewrite spec_w_sub; auto with zarith. - rewrite spec_w_0. - simpl ww_to_Z; autorewrite with rm10. - rewrite Hv6; rewrite spec_w_zdigits. - rewrite (fun x y => Zmod_small (x - y)). - ring_simplify (Zpos w_digits - (Zpos w_digits - [[ww_head1 x]] / 2)). - rewrite Zmod_small. - simpl ww_to_Z in H2; rewrite H2; auto with zarith. - intros (H4, H5); split. - apply Z.mul_le_mono_pos_r with (2 ^ [[ww_head1 x]]); auto with zarith. - rewrite H4. - apply Z.le_trans with ([|w2|] ^ 2); auto with zarith. - rewrite Z.mul_comm. - pattern [[ww_head1 x]] at 1; - rewrite Hv0; auto with zarith. - rewrite (Z.mul_comm 2); rewrite Z.pow_mul_r; - auto with zarith. - assert (tmp: forall p q, p ^ 2 * q ^ 2 = (p * q) ^2); - try (intros; repeat rewrite Zsquare_mult; ring); - rewrite tmp; clear tmp. - apply Zpower_le_monotone3; auto with zarith. - split; auto with zarith. - pattern [|w2|] at 2; - rewrite (Z_div_mod_eq [|w2|] (2 ^ ([[ww_head1 x]] / 2))); - auto with zarith. - match goal with |- ?X <= ?X + ?Y => - assert (0 <= Y); auto with zarith - end. - case (Z_mod_lt [|w2|] (2 ^ ([[ww_head1 x]] / 2))); auto with zarith. - case c; unfold interp_carry; autorewrite with rm10; - intros w3; assert (V3 := spec_to_Z w3);auto with zarith. - apply Z.mul_lt_mono_pos_r with (2 ^ [[ww_head1 x]]); auto with zarith. - rewrite H4. - apply Z.le_lt_trans with ([|w2|] ^ 2 + 2 * [|w2|]); auto with zarith. - apply Z.lt_le_trans with (([|w2|] + 1) ^ 2); auto with zarith. - match goal with |- ?X < ?Y => - replace Y with (X + 1); auto with zarith - end. - repeat rewrite (Zsquare_mult); ring. - rewrite Z.mul_comm. - pattern [[ww_head1 x]] at 1; rewrite Hv0. - rewrite (Z.mul_comm 2); rewrite Z.pow_mul_r; - auto with zarith. - assert (tmp: forall p q, p ^ 2 * q ^ 2 = (p * q) ^2); - try (intros; repeat rewrite Zsquare_mult; ring); - rewrite tmp; clear tmp. - apply Zpower_le_monotone3; auto with zarith. - split; auto with zarith. - pattern [|w2|] at 1; rewrite (Z_div_mod_eq [|w2|] (2 ^ ([[ww_head1 x]]/2))); - auto with zarith. - rewrite <- Z.add_assoc; rewrite Z.mul_add_distr_l. - autorewrite with rm10; apply Z.add_le_mono_l; auto with zarith. - case (Z_mod_lt [|w2|] (2 ^ ([[ww_head1 x]]/2))); auto with zarith. - split; auto with zarith. - apply Z.le_lt_trans with ([|w2|]); auto with zarith. - apply Zdiv_le_upper_bound; auto with zarith. - pattern [|w2|] at 1; replace [|w2|] with ([|w2|] * 2 ^0); - auto with zarith. - apply Z.mul_le_mono_nonneg_l; auto with zarith. - apply Zpower_le_monotone; auto with zarith. - rewrite Z.pow_0_r; autorewrite with rm10; auto. - split; auto with zarith. - rewrite Hv0 in Hv2; rewrite (Pos2Z.inj_xO w_digits) in Hv2; auto with zarith. - apply Z.le_lt_trans with (Zpos w_digits); auto with zarith. - unfold base; apply Zpower2_lt_lin; auto with zarith. - rewrite spec_w_sub; auto with zarith. - rewrite Hv6; rewrite spec_w_zdigits; auto with zarith. - assert (Hv7: 0 < [[ww_head1 x]]/2); auto with zarith. - rewrite Zmod_small; auto with zarith. - split; auto with zarith. - assert ([[ww_head1 x]]/2 <= Zpos w_digits); auto with zarith. - apply Z.mul_le_mono_pos_r with 2; auto with zarith. - repeat rewrite (fun x => Z.mul_comm x 2). - rewrite <- Hv0; rewrite <- Pos2Z.inj_xO; auto with zarith. - apply Z.le_lt_trans with (Zpos w_digits); auto with zarith. - unfold base; apply Zpower2_lt_lin; auto with zarith. - Qed. - -End DoubleSqrt. |