proposition: Lemma Rnearbyint_error_ZR x : (-1 <= Rnearbyint rnd_ZR x - x <= 1)%R.
proof: Proof. assert (H := (Rnearbyint_error_ZR_neg x, Rnearbyint_error_ZR_pos x)). case H; simpl; lra. Qed.
imports: Coq(Reals ZArith Psatz) Flocq(Core) Xreal