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(*         *   The Coq Proof Assistant / The Coq Development Team       *)
(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
(* <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)         *)
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(** Complements for the reals.Integer and fractional part *)
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Local Open Scope R_scope.
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(** *    Fractional part                                 *)
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Definition Int_part (r:R) : Z := (up r - 1)%Z.
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Definition frac_part (r:R) : R := r - IZR (Int_part r).
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(** *    Properties                                      *)
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Lemma fp_nat : forall r:R, frac_part r = 0 ->  exists c : Z, r = IZR c.