glibc/sysdeps/libm-ieee754/s_fdim.c

/* Return positive difference between arguments.
   Copyright (C) 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <math.h>

double
__fdim (double x, double y)
{
  int clsx = fpclassify (x);
  int clsy = fpclassify (y);

  if (clsx == FP_NAN || clsy == FP_NAN
      || (y < 0 && clsx == FP_INFINITE && clsy == FP_INFINITE))
    /* Raise invalid flag.  */
    return x - y;

  return x < y ? 0 : x - y;
}
weak_alias (__fdim, fdim)
#ifdef NO_LONG_DOUBLE
strong_alias (__fdim, __fdiml)
weak_alias (__fdim, fdiml)
#endif