newlib/libm/mathfp/s_fabs.c

   1
   2 /* @(#)z_fabs.c 1.0 98/08/13 */
   3
   4 /*
   5 FUNCTION
   6        <<fabs>>, <<fabsf>>---absolute value (magnitude)
   7 INDEX
   8         fabs
   9 INDEX
  10         fabsf
  11
  12 SYNOPSIS
  13         #include <math.h>
  14        double fabs(double <[x]>);
  15        float fabsf(float <[x]>);
  16
  17 DESCRIPTION
  18 <<fabs>> and <<fabsf>> calculate
  19 @tex
  20 $|x|$,
  21 @end tex
  22 the absolute value (magnitude) of the argument <[x]>, by direct
  23 manipulation of the bit representation of <[x]>.
  24
  25 RETURNS
  26 The calculated value is returned.
  27
  28 PORTABILITY
  29 <<fabs>> is ANSI.
  30 <<fabsf>> is an extension.
  31
  32 */
  33
  34 /******************************************************************
  35  * Floating-Point Absolute Value
  36  *
  37  * Input:
  38  *   x - floating-point number
  39  *
  40  * Output:
  41  *   absolute value of x
  42  *
  43  * Description:
  44  *   fabs computes the absolute value of a floating point number.
  45  *
  46  *****************************************************************/
  47
  48 #include "fdlibm.h"
  49 #include "zmath.h"
  50
  51 #ifndef _DOUBLE_IS_32BITS
  52
  53 double
  54 fabs (double x)
  55 {
  56   switch (numtest (x))
  57     {
  58       case NAN:
  59         errno = EDOM;
  60         return (x);
  61       case INF:
  62         errno = ERANGE;
  63         return (x);
  64       case 0:
  65         return (0.0);
  66       default:
  67         return (x < 0.0 ? -x : x);
  68     }
  69 }
  70
  71 #endif /* _DOUBLE_IS_32BITS */