math/s_fdim.c

   1 /* Return positive difference between arguments.
   2    Copyright (C) 1997, 2004, 2009 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 <errno.h>
  22 #include <math.h>
  23
  24 double
  25 __fdim (double x, double y)
  26 {
  27   int clsx = fpclassify (x);
  28   int clsy = fpclassify (y);
  29
  30   if (clsx == FP_NAN || clsy == FP_NAN
  31       || (y < 0 && clsx == FP_INFINITE && clsy == FP_INFINITE))
  32     /* Raise invalid flag.  */
  33     return x - y;
  34
  35   if (x <= y)
  36     return 0.0;
  37
  38   double r = x - y;
  39   if (fpclassify (r) == FP_INFINITE)
  40     __set_errno (ERANGE);
  41
  42   return r;
  43 }
  44 weak_alias (__fdim, fdim)
  45 #ifdef NO_LONG_DOUBLE
  46 strong_alias (__fdim, __fdiml)
  47 weak_alias (__fdim, fdiml)
  48 #endif