gomp-20050608-branch/libjava/classpath/native/fdlibm/w_exp.c

   1
   2 /* @(#)w_exp.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         <<exp>>, <<expf>>---exponential
  17 INDEX
  18         exp
  19 INDEX
  20         expf
  21
  22 ANSI_SYNOPSIS
  23         #include <math.h>
  24         double exp(double <[x]>);
  25         float expf(float <[x]>);
  26
  27 TRAD_SYNOPSIS
  28         #include <math.h>
  29         double exp(<[x]>);
  30         double <[x]>;
  31
  32         float expf(<[x]>);
  33         float <[x]>;
  34
  35 DESCRIPTION
  36         <<exp>> and <<expf>> calculate the exponential of <[x]>, that is,
  37         @ifinfo
  38         e raised to the power <[x]> (where e
  39         @end ifinfo
  40         @tex
  41         $e^x$ (where $e$
  42         @end tex
  43         is the base of the natural system of logarithms, approximately 2.71828).
  44
  45         You can use the (non-ANSI) function <<matherr>> to specify
  46         error handling for these functions.
  47
  48 RETURNS
  49         On success, <<exp>> and <<expf>> return the calculated value.
  50         If the result underflows, the returned value is <<0>>.  If the
  51         result overflows, the returned value is <<HUGE_VAL>>.  In
  52         either case, <<errno>> is set to <<ERANGE>>.
  53
  54 PORTABILITY
  55         <<exp>> is ANSI C.  <<expf>> is an extension.
  56
  57 */
  58
  59 /*
  60  * wrapper exp(x)
  61  */
  62
  63 #include "fdlibm.h"
  64 #include <errno.h>
  65
  66 #ifndef _DOUBLE_IS_32BITS
  67
  68 #ifndef _IEEE_LIBM
  69
  70 #ifdef __STDC__
  71 static const double
  72 #else
  73 static double
  74 #endif
  75 o_threshold=  7.09782712893383973096e+02,  /* 0x40862E42, 0xFEFA39EF */
  76 u_threshold= -7.45133219101941108420e+02;  /* 0xc0874910, 0xD52D3051 */
  77
  78 #endif
  79
  80 #ifdef __STDC__
  81         double exp(double x)            /* wrapper exp */
  82 #else
  83         double exp(x)                   /* wrapper exp */
  84         double x;
  85 #endif
  86 {
  87 #ifdef _IEEE_LIBM
  88         return __ieee754_exp(x);
  89 #else
  90         double z;
  91         struct exception exc;
  92         z = __ieee754_exp(x);
  93         if(_LIB_VERSION == _IEEE_) return z;
  94         if(finite(x)) {
  95             if(x>o_threshold) {
  96                 /* exp(finite) overflow */
  97 #ifndef HUGE_VAL
  98 #define HUGE_VAL inf
  99                 double inf = 0.0;
 100
 101                 SET_HIGH_WORD(inf,0x7ff00000);  /* set inf to infinite */
 102 #endif
 103                 exc.type = OVERFLOW;
 104                 exc.name = "exp";
 105                 exc.err = 0;
 106                 exc.arg1 = exc.arg2 = x;
 107                 if (_LIB_VERSION == _SVID_)
 108                   exc.retval = HUGE;
 109                 else
 110                   exc.retval = HUGE_VAL;
 111                 if (_LIB_VERSION == _POSIX_)
 112                   errno = ERANGE;
 113                 else if (!matherr(&exc)) {
 114                         errno = ERANGE;
 115                 }
 116                 if (exc.err != 0)
 117                    errno = exc.err;
 118                 return exc.retval;
 119             } else if(x<u_threshold) {
 120                 /* exp(finite) underflow */
 121                 exc.type = UNDERFLOW;
 122                 exc.name = "exp";
 123                 exc.err = 0;
 124                 exc.arg1 = exc.arg2 = x;
 125                 exc.retval = 0.0;
 126                 if (_LIB_VERSION == _POSIX_)
 127                   errno = ERANGE;
 128                 else if (!matherr(&exc)) {
 129                         errno = ERANGE;
 130                 }
 131                 if (exc.err != 0)
 132                    errno = exc.err;
 133                 return exc.retval;
 134             }
 135         }
 136         return z;
 137 #endif
 138 }
 139
 140 #endif /* defined(_DOUBLE_IS_32BITS) */