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(*         *      The Rocq Prover / The Rocq Development Team           *)
(*  v      *         Copyright INRIA, CNRS and contributors             *)
(* <O___,, * (see version control and CREDITS file for authors & dates) *)
(*   \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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Lemma plus_frac_part1 :
forall r1 r2:R,
frac_part r1 + frac_part r2 >= 1 ->
frac_part (r1 + r2) = frac_part r1 + frac_part r2 - 1.