diff options
| -rw-r--r-- | doc/changelog/10-standard-library/09811-remove-zlogarithm.rst | 3 | ||||
| -rw-r--r-- | doc/stdlib/index-list.html.template | 1 | ||||
| -rw-r--r-- | theories/Numbers/Cyclic/ZModulo/ZModulo.v | 58 | ||||
| -rw-r--r-- | theories/ZArith/ZArith.v | 1 | ||||
| -rw-r--r-- | theories/ZArith/Zlogarithm.v | 273 |
5 files changed, 19 insertions, 317 deletions
diff --git a/doc/changelog/10-standard-library/09811-remove-zlogarithm.rst b/doc/changelog/10-standard-library/09811-remove-zlogarithm.rst new file mode 100644 index 0000000000..3533764964 --- /dev/null +++ b/doc/changelog/10-standard-library/09811-remove-zlogarithm.rst @@ -0,0 +1,3 @@ +- Removes deprecated module `Coq.ZArith.Zlogarithm` + (#9881 <https://github.com/coq/coq/pull/9811> + by Vincent Laporte). diff --git a/doc/stdlib/index-list.html.template b/doc/stdlib/index-list.html.template index a561de1d0c..8d481b7f03 100644 --- a/doc/stdlib/index-list.html.template +++ b/doc/stdlib/index-list.html.template @@ -188,7 +188,6 @@ through the <tt>Require Import</tt> command.</p> theories/ZArith/Zdiv.v theories/ZArith/Zquot.v theories/ZArith/Zeuclid.v - theories/ZArith/Zlogarithm.v (theories/ZArith/ZArith.v) theories/ZArith/Zgcd_alt.v theories/ZArith/Zwf.v diff --git a/theories/Numbers/Cyclic/ZModulo/ZModulo.v b/theories/Numbers/Cyclic/ZModulo/ZModulo.v index 28565b2fe3..2785e89c5d 100644 --- a/theories/Numbers/Cyclic/ZModulo/ZModulo.v +++ b/theories/Numbers/Cyclic/ZModulo/ZModulo.v @@ -648,40 +648,15 @@ Section ZModulo. apply two_power_pos_correct. Qed. - Definition head0 x := match [|x|] with + Definition head0 x := + match [| x |] with | Z0 => zdigits - | Zpos p => zdigits - log_inf p - 1 - | _ => 0 - end. + | Zneg _ => 0 + | (Zpos _) as p => zdigits - Z.log2 p - 1 + end. Lemma spec_head00: forall x, [|x|] = 0 -> [|head0 x|] = Zpos digits. - Proof. - unfold head0; intros. - rewrite H; simpl. - apply spec_zdigits. - Qed. - - Lemma log_inf_bounded : forall x p, Zpos x < 2^p -> log_inf x < p. - Proof. - induction x; simpl; intros. - - assert (0 < p) by (destruct p; compute; auto with zarith; discriminate). - cut (log_inf x < p - 1); [omega| ]. - apply IHx. - change (Zpos x~1) with (2*(Zpos x)+1) in H. - replace p with (Z.succ (p-1)) in H; auto with zarith. - rewrite Z.pow_succ_r in H; auto with zarith. - - assert (0 < p) by (destruct p; compute; auto with zarith; discriminate). - cut (log_inf x < p - 1); [omega| ]. - apply IHx. - change (Zpos x~0) with (2*(Zpos x)) in H. - replace p with (Z.succ (p-1)) in H; auto with zarith. - rewrite Z.pow_succ_r in H; auto with zarith. - - simpl; intros; destruct p; compute; auto with zarith. - Qed. - + Proof. unfold head0; intros x ->; apply spec_zdigits. Qed. Lemma spec_head0 : forall x, 0 < [|x|] -> wB/ 2 <= 2 ^ ([|head0 x|]) * [|x|] < wB. @@ -689,36 +664,35 @@ Section ZModulo. intros; unfold head0. generalize (spec_to_Z x). destruct [|x|]; try discriminate. + pose proof (Z.log2_nonneg (Zpos p)). + destruct (Z.log2_spec (Zpos p)); auto. intros. - destruct (log_inf_correct p). - rewrite 2 two_p_power2 in H2; auto with zarith. - assert (0 <= zdigits - log_inf p - 1 < wB). + assert (0 <= zdigits - Z.log2 (Zpos p) - 1 < wB) as Hrange. split. - cut (log_inf p < zdigits); try omega. + cut (Z.log2 (Zpos p) < zdigits). omega. unfold zdigits. unfold wB, base in *. - apply log_inf_bounded; auto with zarith. + apply Z.log2_lt_pow2; intuition. apply Z.lt_trans with zdigits. omega. unfold zdigits, wB, base; apply Zpower2_lt_lin; auto with zarith. - unfold to_Z; rewrite (Zmod_small _ _ H3). - destruct H2. + unfold to_Z; rewrite (Zmod_small _ _ Hrange). split. - apply Z.le_trans with (2^(zdigits - log_inf p - 1)*(2^log_inf p)). + apply Z.le_trans with (2^(zdigits - Z.log2 (Zpos p) - 1)*(2^Z.log2 (Zpos p))). apply Zdiv_le_upper_bound; auto with zarith. rewrite <- Zpower_exp; auto with zarith. rewrite Z.mul_comm; rewrite <- Z.pow_succ_r; auto with zarith. - replace (Z.succ (zdigits - log_inf p -1 +log_inf p)) with zdigits + replace (Z.succ (zdigits - Z.log2 (Zpos p) -1 + Z.log2 (Zpos p))) with zdigits by ring. unfold wB, base, zdigits; auto with zarith. apply Z.mul_le_mono_nonneg; auto with zarith. apply Z.lt_le_trans - with (2^(zdigits - log_inf p - 1)*(2^(Z.succ (log_inf p)))). + with (2^(zdigits - Z.log2 (Zpos p) - 1)*(2^(Z.succ (Z.log2 (Zpos p))))). apply Z.mul_lt_mono_pos_l; auto with zarith. rewrite <- Zpower_exp; auto with zarith. - replace (zdigits - log_inf p -1 +Z.succ (log_inf p)) with zdigits + replace (zdigits - Z.log2 (Zpos p) -1 +Z.succ (Z.log2 (Zpos p))) with zdigits by ring. unfold wB, base, zdigits; auto with zarith. Qed. diff --git a/theories/ZArith/ZArith.v b/theories/ZArith/ZArith.v index c2c97fca4f..b0744caa7b 100644 --- a/theories/ZArith/ZArith.v +++ b/theories/ZArith/ZArith.v @@ -21,6 +21,5 @@ Require Export Zpow_def. Require Export Zcomplements. Require Export Zpower. Require Export Zdiv. -Require Export Zlogarithm. Export ZArithRing. diff --git a/theories/ZArith/Zlogarithm.v b/theories/ZArith/Zlogarithm.v deleted file mode 100644 index edbd3a18fe..0000000000 --- a/theories/ZArith/Zlogarithm.v +++ /dev/null @@ -1,273 +0,0 @@ -(************************************************************************) -(* * The Coq Proof Assistant / The Coq Development Team *) -(* v * INRIA, CNRS and contributors - Copyright 1999-2019 *) -(* <O___,, * (see CREDITS file for the list of authors) *) -(* \VV/ **************************************************************) -(* // * This file is distributed under the terms of the *) -(* * GNU Lesser General Public License Version 2.1 *) -(* * (see LICENSE file for the text of the license) *) -(************************************************************************) - -(**********************************************************************) - -(** The integer logarithms with base 2. *) - -(** THIS FILE IS DEPRECATED. - Please rather use [Z.log2] (or [Z.log2_up]), which - are defined in [BinIntDef], and whose properties can - be found in [BinInt.Z]. *) - -(* There are three logarithms defined here, - depending on the rounding of the real 2-based logarithm: - - [Log_inf]: [y = (Log_inf x) iff 2^y <= x < 2^(y+1)] - i.e. [Log_inf x] is the biggest integer that is smaller than [Log x] - - [Log_sup]: [y = (Log_sup x) iff 2^(y-1) < x <= 2^y] - i.e. [Log_inf x] is the smallest integer that is bigger than [Log x] - - [Log_nearest]: [y= (Log_nearest x) iff 2^(y-1/2) < x <= 2^(y+1/2)] - i.e. [Log_nearest x] is the integer nearest from [Log x] *) - -Require Import ZArith_base Omega Zcomplements Zpower. -Local Open Scope Z_scope. - -Section Log_pos. (* Log of positive integers *) - - (** First we build [log_inf] and [log_sup] *) - - Fixpoint log_inf (p:positive) : Z := - match p with - | xH => 0 (* 1 *) - | xO q => Z.succ (log_inf q) (* 2n *) - | xI q => Z.succ (log_inf q) (* 2n+1 *) - end. - - Fixpoint log_sup (p:positive) : Z := - match p with - | xH => 0 (* 1 *) - | xO n => Z.succ (log_sup n) (* 2n *) - | xI n => Z.succ (Z.succ (log_inf n)) (* 2n+1 *) - end. - - Hint Unfold log_inf log_sup : core. - - Lemma Psize_log_inf : forall p, Zpos (Pos.size p) = Z.succ (log_inf p). - Proof. - induction p; simpl; now rewrite ?Pos2Z.inj_succ, ?IHp. - Qed. - - Lemma Zlog2_log_inf : forall p, Z.log2 (Zpos p) = log_inf p. - Proof. - unfold Z.log2. destruct p; simpl; trivial; apply Psize_log_inf. - Qed. - - Lemma Zlog2_up_log_sup : forall p, Z.log2_up (Zpos p) = log_sup p. - Proof. - induction p; simpl log_sup. - - change (Zpos p~1) with (2*(Zpos p)+1). - rewrite Z.log2_up_succ_double, Zlog2_log_inf; try easy. - unfold Z.succ. now rewrite !(Z.add_comm _ 1), Z.add_assoc. - - change (Zpos p~0) with (2*Zpos p). - now rewrite Z.log2_up_double, IHp. - - reflexivity. - Qed. - - (** Then we give the specifications of [log_inf] and [log_sup] - and prove their validity *) - - Hint Resolve Z.le_trans: zarith. - - Theorem log_inf_correct : - forall x:positive, - 0 <= log_inf x /\ two_p (log_inf x) <= Zpos x < two_p (Z.succ (log_inf x)). - Proof. - simple induction x; intros; simpl; - [ elim H; intros Hp HR; clear H; split; - [ auto with zarith - | rewrite two_p_S with (x := Z.succ (log_inf p)) by (apply Z.le_le_succ_r; trivial); - rewrite two_p_S by trivial; - rewrite two_p_S in HR by trivial; rewrite (BinInt.Pos2Z.inj_xI p); - omega ] - | elim H; intros Hp HR; clear H; split; - [ auto with zarith - | rewrite two_p_S with (x := Z.succ (log_inf p)) by (apply Z.le_le_succ_r; trivial); - rewrite two_p_S by trivial; - rewrite two_p_S in HR by trivial; rewrite (BinInt.Pos2Z.inj_xO p); - omega ] - | unfold two_power_pos; unfold shift_pos; simpl; - omega ]. - Qed. - - Definition log_inf_correct1 (p:positive) := proj1 (log_inf_correct p). - Definition log_inf_correct2 (p:positive) := proj2 (log_inf_correct p). - - Opaque log_inf_correct1 log_inf_correct2. - - Hint Resolve log_inf_correct1 log_inf_correct2: zarith. - - Lemma log_sup_correct1 : forall p:positive, 0 <= log_sup p. - Proof. - simple induction p; intros; simpl; auto with zarith. - Qed. - - (** For every [p], either [p] is a power of two and [(log_inf p)=(log_sup p)] - either [(log_sup p)=(log_inf p)+1] *) - - Theorem log_sup_log_inf : - forall p:positive, - IF Zpos p = two_p (log_inf p) then Zpos p = two_p (log_sup p) - else log_sup p = Z.succ (log_inf p). - Proof. - simple induction p; intros; - [ elim H; right; simpl; - rewrite (two_p_S (log_inf p0) (log_inf_correct1 p0)); - rewrite BinInt.Pos2Z.inj_xI; unfold Z.succ; omega - | elim H; clear H; intro Hif; - [ left; simpl; - rewrite (two_p_S (log_inf p0) (log_inf_correct1 p0)); - rewrite (two_p_S (log_sup p0) (log_sup_correct1 p0)); - rewrite <- (proj1 Hif); rewrite <- (proj2 Hif); - auto - | right; simpl; - rewrite (two_p_S (log_inf p0) (log_inf_correct1 p0)); - rewrite BinInt.Pos2Z.inj_xO; unfold Z.succ; - omega ] - | left; auto ]. - Qed. - - Theorem log_sup_correct2 : - forall x:positive, two_p (Z.pred (log_sup x)) < Zpos x <= two_p (log_sup x). - Proof. - intro. - elim (log_sup_log_inf x). - (* x is a power of two and [log_sup = log_inf] *) - intros [E1 E2]; rewrite E2. - split; [ apply two_p_pred; apply log_sup_correct1 | apply Z.le_refl ]. - intros [E1 E2]; rewrite E2. - rewrite (Z.pred_succ (log_inf x)). - generalize (log_inf_correct2 x); omega. - Qed. - - Lemma log_inf_le_log_sup : forall p:positive, log_inf p <= log_sup p. - Proof. - simple induction p; simpl; intros; omega. - Qed. - - Lemma log_sup_le_Slog_inf : forall p:positive, log_sup p <= Z.succ (log_inf p). - Proof. - simple induction p; simpl; intros; omega. - Qed. - - (** Now it's possible to specify and build the [Log] rounded to the nearest *) - - Fixpoint log_near (x:positive) : Z := - match x with - | xH => 0 - | xO xH => 1 - | xI xH => 2 - | xO y => Z.succ (log_near y) - | xI y => Z.succ (log_near y) - end. - - Theorem log_near_correct1 : forall p:positive, 0 <= log_near p. - Proof. - simple induction p; simpl; intros; - [ elim p0; auto with zarith - | elim p0; auto with zarith - | trivial with zarith ]. - intros; apply Z.le_le_succ_r. - generalize H0; now elim p1. - intros; apply Z.le_le_succ_r. - generalize H0; now elim p1. - Qed. - - Theorem log_near_correct2 : - forall p:positive, log_near p = log_inf p \/ log_near p = log_sup p. - Proof. - simple induction p. - intros p0 [Einf| Esup]. - simpl. rewrite Einf. - case p0; [ left | left | right ]; reflexivity. - simpl; rewrite Esup. - elim (log_sup_log_inf p0). - generalize (log_inf_le_log_sup p0). - generalize (log_sup_le_Slog_inf p0). - case p0; auto with zarith. - intros; omega. - case p0; intros; auto with zarith. - intros p0 [Einf| Esup]. - simpl. - repeat rewrite Einf. - case p0; intros; auto with zarith. - simpl. - repeat rewrite Esup. - case p0; intros; auto with zarith. - auto. - Qed. - -End Log_pos. - -Section divers. - - (** Number of significative digits. *) - - Definition N_digits (x:Z) := - match x with - | Zpos p => log_inf p - | Zneg p => log_inf p - | Z0 => 0 - end. - - Lemma ZERO_le_N_digits : forall x:Z, 0 <= N_digits x. - Proof. - simple induction x; simpl; - [ apply Z.le_refl | exact log_inf_correct1 | exact log_inf_correct1 ]. - Qed. - - Lemma log_inf_shift_nat : forall n:nat, log_inf (shift_nat n 1) = Z.of_nat n. - Proof. - simple induction n; intros; - [ try trivial | rewrite Nat2Z.inj_succ; rewrite <- H; reflexivity ]. - Qed. - - Lemma log_sup_shift_nat : forall n:nat, log_sup (shift_nat n 1) = Z.of_nat n. - Proof. - simple induction n; intros; - [ try trivial | rewrite Nat2Z.inj_succ; rewrite <- H; reflexivity ]. - Qed. - - (** [Is_power p] means that p is a power of two *) - Fixpoint Is_power (p:positive) : Prop := - match p with - | xH => True - | xO q => Is_power q - | xI q => False - end. - - Lemma Is_power_correct : - forall p:positive, Is_power p <-> (exists y : nat, p = shift_nat y 1). - Proof. - split; - [ elim p; - [ simpl; tauto - | simpl; intros; generalize (H H0); intro H1; elim H1; - intros y0 Hy0; exists (S y0); rewrite Hy0; reflexivity - | intro; exists 0%nat; reflexivity ] - | intros; elim H; intros; rewrite H0; elim x; intros; simpl; trivial ]. - Qed. - - Lemma Is_power_or : forall p:positive, Is_power p \/ ~ Is_power p. - Proof. - simple induction p; - [ intros; right; simpl; tauto - | intros; elim H; - [ intros; left; simpl; exact H0 - | intros; right; simpl; exact H0 ] - | left; simpl; trivial ]. - Qed. - -End divers. - - - - - - |