sysdeps/libm-ieee754/w_exp.c

   1 /* @(#)w_exp.c 5.1 93/09/24 */
   2 /*
   3  * ====================================================
   4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   5  *
   6  * Developed at SunPro, a Sun Microsystems, Inc. business.
   7  * Permission to use, copy, modify, and distribute this
   8  * software is freely granted, provided that this notice
   9  * is preserved.
  10  * ====================================================
  11  */
  12
  13 #if defined(LIBM_SCCS) && !defined(lint)
  14 static char rcsid[] = "$NetBSD: w_exp.c,v 1.6 1995/05/10 20:48:51 jtc Exp $";
  15 #endif
  16
  17 /*
  18  * wrapper exp(x)
  19  */
  20
  21 #include "math.h"
  22 #include "math_private.h"
  23
  24 #ifdef __STDC__
  25 static const double
  26 #else
  27 static double
  28 #endif
  29 o_threshold=  7.09782712893383973096e+02,  /* 0x40862E42, 0xFEFA39EF */
  30 u_threshold= -7.45133219101941108420e+02;  /* 0xc0874910, 0xD52D3051 */
  31
  32 #ifdef __STDC__
  33         double __exp(double x)          /* wrapper exp */
  34 #else
  35         double __exp(x)                 /* wrapper exp */
  36         double x;
  37 #endif
  38 {
  39 #ifdef _IEEE_LIBM
  40         return __ieee754_exp(x);
  41 #else
  42         double z;
  43         z = __ieee754_exp(x);
  44         if(_LIB_VERSION == _IEEE_) return z;
  45         if(__finite(x)) {
  46             if(x>o_threshold)
  47                 return __kernel_standard(x,x,6); /* exp overflow */
  48             else if(x<u_threshold)
  49                 return __kernel_standard(x,x,7); /* exp underflow */
  50         }
  51         return z;
  52 #endif
  53 }
  54 weak_alias (__exp, exp)