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-rw-r--r--theories/QArith/Qround.v13
1 files changed, 12 insertions, 1 deletions
diff --git a/theories/QArith/Qround.v b/theories/QArith/Qround.v
index 58a7967ed..ce363a33b 100644
--- a/theories/QArith/Qround.v
+++ b/theories/QArith/Qround.v
@@ -136,4 +136,15 @@ intros x y H.
apply Zle_antisym.
auto with *.
symmetry in H; auto with *.
-Qed. \ No newline at end of file
+Qed.
+
+Lemma Zdiv_Qdiv (n m: Z): (n / m)%Z = Qfloor (n / m).
+Proof.
+ unfold Qfloor. intros. simpl.
+ destruct m as [?|?|p]; simpl.
+ now rewrite Zdiv_0_r, Zmult_0_r.
+ now rewrite Zmult_1_r.
+ rewrite <- Zopp_eq_mult_neg_1.
+ rewrite <- (Zopp_involutive (Zpos p)).
+ now rewrite Zdiv_opp_opp.
+Qed.