newlib/libm/common/s_fdim.c

   1 /* Copyright (C) 2002 by  Red Hat, Incorporated. All rights reserved.
   2  *
   3  * Permission to use, copy, modify, and distribute this software
   4  * is freely granted, provided that this notice is preserved.
   5  */
   6 /*
   7 FUNCTION
   8 <<fdim>>, <<fdimf>>---positive difference
   9 INDEX
  10         fdim
  11 INDEX
  12         fdimf
  13
  14 SYNOPSIS
  15         #include <math.h>
  16         double fdim(double <[x]>, double <[y]>);
  17         float fdimf(float <[x]>, float <[y]>);
  18
  19 DESCRIPTION
  20 The <<fdim>> functions determine the positive difference between their
  21 arguments, returning:
  22 .       <[x]> - <[y]>   if <[x]> > <[y]>, or
  23         @ifnottex
  24 .       +0      if <[x]> <= <[y]>, or
  25         @end ifnottex
  26         @tex
  27 .       +0      if <[x]> $\leq$ <[y]>, or
  28         @end tex
  29 .       NAN     if either argument is NAN.
  30 A range error may occur.
  31
  32 RETURNS
  33 The <<fdim>> functions return the positive difference value.
  34
  35 PORTABILITY
  36 ANSI C, POSIX.
  37
  38 */
  39
  40 #include "fdlibm.h"
  41
  42 #ifndef _DOUBLE_IS_32BITS
  43
  44 #ifdef __STDC__
  45         double fdim(double x, double y)
  46 #else
  47         double fdim(x,y)
  48         double x;
  49         double y;
  50 #endif
  51 {
  52   if (__fpclassifyd(x) == FP_NAN)  return(x);
  53   if (__fpclassifyd(y) == FP_NAN)  return(y);
  54
  55   return x > y ? x - y : 0.0;
  56 }
  57
  58 #endif /* _DOUBLE_IS_32BITS */