newlib/libm/math/w_exp2.c

   1
   2 /* @(#)w_exp2.c 5.1 93/09/24 */
   3 /*
   4  * ====================================================
   5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   6  *
   7  * Developed at SunPro, a Sun Microsystems, Inc. business.
   8  * Permission to use, copy, modify, and distribute this
   9  * software is freely granted, provided that this notice
  10  * is preserved.
  11  * ====================================================
  12  */
  13
  14 /*
  15 FUNCTION
  16         <<exp2>>, <<exp2f>>---exponential, base 2
  17 INDEX
  18         exp2
  19 INDEX
  20         exp2f
  21
  22 SYNOPSIS
  23         #include <math.h>
  24         double exp2(double <[x]>);
  25         float exp2f(float <[x]>);
  26
  27 DESCRIPTION
  28         <<exp2>> and <<exp2f>> calculate 2 ^ <[x]>, that is,
  29         @ifnottex
  30         2 raised to the power <[x]>.
  31         @end ifnottex
  32         @tex
  33         $2^x$
  34         @end tex
  35
  36 RETURNS
  37         On success, <<exp2>> and <<exp2f>> return the calculated value.
  38         If the result underflows, the returned value is <<0>>.  If the
  39         result overflows, the returned value is <<HUGE_VAL>>.  In
  40         either case, <<errno>> is set to <<ERANGE>>.
  41
  42 PORTABILITY
  43         ANSI C, POSIX.
  44
  45 */
  46
  47 /*
  48  * wrapper exp2(x)
  49  */
  50
  51 #include "fdlibm.h"
  52 #if __OBSOLETE_MATH
  53 #include <errno.h>
  54 #include <math.h>
  55
  56 #ifndef _DOUBLE_IS_32BITS
  57
  58 #ifdef __STDC__
  59         double exp2(double x)           /* wrapper exp2 */
  60 #else
  61         double exp2(x)                  /* wrapper exp2 */
  62         double x;
  63 #endif
  64 {
  65   return pow(2.0, x);
  66 }
  67
  68 #endif /* defined(_DOUBLE_IS_32BITS) */
  69 #endif /* __OBSOLETE_MATH */