diff options
Diffstat (limited to 'theories/ZArith/Zpower.v')
| -rw-r--r-- | theories/ZArith/Zpower.v | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/theories/ZArith/Zpower.v b/theories/ZArith/Zpower.v index 27f0cfd2..747bd4fd 100644 --- a/theories/ZArith/Zpower.v +++ b/theories/ZArith/Zpower.v @@ -1,6 +1,6 @@ (************************************************************************) (* v * The Coq Proof Assistant / The Coq Development Team *) -(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2014 *) +(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2015 *) (* \VV/ **************************************************************) (* // * This file is distributed under the terms of the *) (* * GNU Lesser General Public License Version 2.1 *) @@ -25,7 +25,7 @@ Local Open Scope Z_scope. (** [Zpower_nat z n] is the n-th power of [z] when [n] is an unary integer (type [nat]) and [z] a signed integer (type [Z]) *) -Definition Zpower_nat (z:Z) (n:nat) := nat_iter n (Z.mul z) 1. +Definition Zpower_nat (z:Z) := nat_rect _ 1 (fun _ => Z.mul z). Lemma Zpower_nat_0_r z : Zpower_nat z 0 = 1. Proof. reflexivity. Qed. @@ -42,7 +42,7 @@ Lemma Zpower_nat_is_exp : Proof. induction n. - intros. now rewrite Zpower_nat_0_r, Z.mul_1_l. - - intros. simpl. now rewrite 2 Zpower_nat_succ_r, IHn, Z.mul_assoc. + - intros. simpl. now rewrite IHn, Z.mul_assoc. Qed. (** Conversions between powers of unary and binary integers *) @@ -94,12 +94,12 @@ Section Powers_of_2. calculus is possible. [shift n m] computes [2^n * m], i.e. [m] shifted by [n] positions *) - Definition shift_nat (n:nat) (z:positive) := nat_iter n xO z. - Definition shift_pos (n z:positive) := Pos.iter n xO z. + Definition shift_nat (n:nat) (z:positive) := nat_rect _ z (fun _ => xO) n. + Definition shift_pos (n z:positive) := Pos.iter xO z n. Definition shift (n:Z) (z:positive) := match n with | Z0 => z - | Zpos p => Pos.iter p xO z + | Zpos p => Pos.iter xO z p | Zneg p => z end. @@ -154,7 +154,7 @@ Section Powers_of_2. Lemma shift_nat_plus n m x : shift_nat (n + m) x = shift_nat n (shift_nat m x). Proof. - apply iter_nat_plus. + induction n; simpl; now f_equal. Qed. Theorem shift_nat_correct n x : @@ -247,20 +247,20 @@ Section power_div_with_rest. end, 2 * d). Definition Zdiv_rest (x:Z) (p:positive) := - let (qr, d) := Pos.iter p Zdiv_rest_aux (x, 0, 1) in qr. + let (qr, d) := Pos.iter Zdiv_rest_aux (x, 0, 1) p in qr. Lemma Zdiv_rest_correct1 (x:Z) (p:positive) : - let (_, d) := Pos.iter p Zdiv_rest_aux (x, 0, 1) in + let (_, d) := Pos.iter Zdiv_rest_aux (x, 0, 1) p in d = two_power_pos p. Proof. rewrite Pos2Nat.inj_iter, two_power_pos_nat. induction (Pos.to_nat p); simpl; trivial. - destruct (nat_iter n Zdiv_rest_aux (x,0,1)) as ((q,r),d). + destruct (nat_rect _ _ _ _) as ((q,r),d). unfold Zdiv_rest_aux. rewrite two_power_nat_S; now f_equal. Qed. Lemma Zdiv_rest_correct2 (x:Z) (p:positive) : - let '(q,r,d) := Pos.iter p Zdiv_rest_aux (x, 0, 1) in + let '(q,r,d) := Pos.iter Zdiv_rest_aux (x, 0, 1) p in x = q * d + r /\ 0 <= r < d. Proof. apply Pos.iter_invariant; [|omega]. @@ -287,7 +287,7 @@ Section power_div_with_rest. Lemma Zdiv_rest_correct (x:Z) (p:positive) : Zdiv_rest_proofs x p. Proof. generalize (Zdiv_rest_correct1 x p); generalize (Zdiv_rest_correct2 x p). - destruct (Pos.iter p Zdiv_rest_aux (x, 0, 1)) as ((q,r),d). + destruct (Pos.iter Zdiv_rest_aux (x, 0, 1) p) as ((q,r),d). intros (H1,(H2,H3)) ->. now exists q r. Qed. @@ -299,7 +299,7 @@ Section power_div_with_rest. Proof. unfold Zdiv_rest. generalize (Zdiv_rest_correct1 x p); generalize (Zdiv_rest_correct2 x p). - destruct (Pos.iter p Zdiv_rest_aux (x, 0, 1)) as ((q,r),d). + destruct (Pos.iter Zdiv_rest_aux (x, 0, 1) p) as ((q,r),d). intros H ->. now rewrite two_power_pos_equiv in H. Qed. |