source/libs/mpfr/mpfr-3.1.3/src/copysign.c

   1 /* mpfr_copysign -- Produce a value with the magnitude of x and sign bit of y
   2
   3 Copyright 2001-2004, 2006-2015 Free Software Foundation, Inc.
   4 Contributed by the AriC and Caramel projects, INRIA.
   5
   6 This file is part of the GNU MPFR Library.
   7
   8 The GNU MPFR Library is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU Lesser General Public License as published by
  10 the Free Software Foundation; either version 3 of the License, or (at your
  11 option) any later version.
  12
  13 The GNU MPFR Library is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  16 License for more details.
  17
  18 You should have received a copy of the GNU Lesser General Public License
  19 along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
  20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
  21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
  22
  23 #include "mpfr-impl.h"
  24
  25  /*
  26    The computation of z with magnitude of x and sign of y:
  27    z = (-1)^signbit(y) * abs(x), i.e. with the same sign bit as y,
  28    even if z is a NaN.
  29    Note: This function implements copysign from the IEEE-754 standard
  30    when no rounding occurs (e.g. if PREC(z) >= PREC(x)).
  31  */
  32
  33 #undef mpfr_copysign
  34 int
  35 mpfr_copysign (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, mpfr_rnd_t rnd_mode)
  36 {
  37   return mpfr_set4 (z, x, rnd_mode, MPFR_SIGN (y));
  38 }