math/s_fdim.c

   1 /* Return positive difference between arguments.
   2    Copyright (C) 1997, 2004 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <math.h>
  22
  23 double
  24 __fdim (double x, double y)
  25 {
  26   int clsx = fpclassify (x);
  27   int clsy = fpclassify (y);
  28
  29   if (clsx == FP_NAN || clsy == FP_NAN
  30       || (y < 0 && clsx == FP_INFINITE && clsy == FP_INFINITE))
  31     /* Raise invalid flag.  */
  32     return x - y;
  33
  34   return x <= y ? 0 : x - y;
  35 }
  36 weak_alias (__fdim, fdim)
  37 #ifdef NO_LONG_DOUBLE
  38 strong_alias (__fdim, __fdiml)
  39 weak_alias (__fdim, fdiml)
  40 #endif