source: trunk/src/gcc/libjava/java/lang/w_exp.c@ 2

Last change on this file since 2 was 2, checked in by bird, 23 years ago

Initial revision
  • Property cvs2svn:cvs-rev set to 1.1
  • Property svn:eol-style set to native
  • Property svn:executable set to *
File size: 2.8 KB
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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/*
15FUNCTION
16 <<exp>>, <<expf>>---exponential
17INDEX
18 exp
19INDEX
20 expf
21
22ANSI_SYNOPSIS
23 #include <math.h>
24 double exp(double <[x]>);
25 float expf(float <[x]>);
26
27TRAD_SYNOPSIS
28 #include <math.h>
29 double exp(<[x]>);
30 double <[x]>;
31
32 float expf(<[x]>);
33 float <[x]>;
34
35DESCRIPTION
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
48RETURNS
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
54PORTABILITY
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#ifdef __STDC__
69static const double
70#else
71static double
72#endif
73o_threshold= 7.09782712893383973096e+02, /* 0x40862E42, 0xFEFA39EF */
74u_threshold= -7.45133219101941108420e+02; /* 0xc0874910, 0xD52D3051 */
75
76#ifdef __STDC__
77 double exp(double x) /* wrapper exp */
78#else
79 double exp(x) /* wrapper exp */
80 double x;
81#endif
82{
83#ifdef _IEEE_LIBM
84 return __ieee754_exp(x);
85#else
86 double z;
87 struct exception exc;
88 z = __ieee754_exp(x);
89 if(_LIB_VERSION == _IEEE_) return z;
90 if(finite(x)) {
91 if(x>o_threshold) {
92 /* exp(finite) overflow */
93#ifndef HUGE_VAL
94#define HUGE_VAL inf
95 double inf = 0.0;
96
97 SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */
98#endif
99 exc.type = OVERFLOW;
100 exc.name = "exp";
101 exc.err = 0;
102 exc.arg1 = exc.arg2 = x;
103 if (_LIB_VERSION == _SVID_)
104 exc.retval = HUGE;
105 else
106 exc.retval = HUGE_VAL;
107 if (_LIB_VERSION == _POSIX_)
108 errno = ERANGE;
109 else if (!matherr(&exc)) {
110 errno = ERANGE;
111 }
112 if (exc.err != 0)
113 errno = exc.err;
114 return exc.retval;
115 } else if(x<u_threshold) {
116 /* exp(finite) underflow */
117 exc.type = UNDERFLOW;
118 exc.name = "exp";
119 exc.err = 0;
120 exc.arg1 = exc.arg2 = x;
121 exc.retval = 0.0;
122 if (_LIB_VERSION == _POSIX_)
123 errno = ERANGE;
124 else if (!matherr(&exc)) {
125 errno = ERANGE;
126 }
127 if (exc.err != 0)
128 errno = exc.err;
129 return exc.retval;
130 }
131 }
132 return z;
133#endif
134}
135
136#endif /* defined(_DOUBLE_IS_32BITS) */
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