OpenCores
URL https://opencores.org/ocsvn/openrisc_2011-10-31/openrisc_2011-10-31/trunk

Subversion Repositories openrisc_2011-10-31

[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libm/] [math/] [w_log.c] - Blame information for rev 617

Go to most recent revision | Details | Compare with Previous | View Log

Line No. Rev Author Line
1 148 jeremybenn 
 
2 
/* @(#)w_log.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 
       <<log>>, <<logf>>---natural logarithms
17 
 
18 
INDEX
19 
    log
20 
INDEX
21 
    logf
22 
 
23 
ANSI_SYNOPSIS
24 
       #include <math.h>
25 
       double log(double <[x]>);
26 
       float logf(float <[x]>);
27 
 
28 
TRAD_SYNOPSIS
29 
       #include <math.h>
30 
       double log(<[x]>);
31 
       double <[x]>;
32 
 
33 
       float logf(<[x]>);
34 
       float <[x]>;
35 
 
36 
DESCRIPTION
37 
Return the natural logarithm of <[x]>, that is, its logarithm base e
38 
(where e is the base of the natural system of logarithms, 2.71828@dots{}).
39 
<<log>> and <<logf>> are identical save for the return and argument types.
40 
 
41 
You can use the (non-ANSI) function <<matherr>> to specify error
42 
handling for these functions.
43 
 
44 
RETURNS
45 
Normally, returns the calculated value.  When <[x]> is zero, the
46 
returned value is <<-HUGE_VAL>> and <<errno>> is set to <<ERANGE>>.
47 
When <[x]> is negative, the returned value is NaN (not a number) and
48 
<<errno>> is set to <<EDOM>>.  You can control the error behavior via
49 
<<matherr>>.
50 
 
51 
PORTABILITY
52 
<<log>> is ANSI. <<logf>> is an extension.
53 
*/
54 
 
55 
/*
56 
 * wrapper log(x)
57 
 */
58 
 
59 
#include "fdlibm.h"
60 
#include <errno.h>
61 
 
62 
#ifndef _DOUBLE_IS_32BITS
63 
 
64 
#ifdef __STDC__
65 
        double log(double x)            /* wrapper log */
66 
#else
67 
        double log(x)                   /* wrapper log */
68 
        double x;
69 
#endif
70 
{
71 
#ifdef _IEEE_LIBM
72 
        return __ieee754_log(x);
73 
#else
74 
        double z;
75 
        struct exception exc;
76 
        z = __ieee754_log(x);
77 
        if(_LIB_VERSION == _IEEE_ || isnan(x) || x > 0.0) return z;
78 
#ifndef HUGE_VAL
79 
#define HUGE_VAL inf
80 
        double inf = 0.0;
81 
 
82 
        SET_HIGH_WORD(inf,0x7ff00000);  /* set inf to infinite */
83 
#endif
84 
        exc.name = "log";
85 
        exc.err = 0;
86 
        exc.arg1 = x;
87 
        exc.arg2 = x;
88 
        if (_LIB_VERSION == _SVID_)
89 
           exc.retval = -HUGE;
90 
        else
91 
           exc.retval = -HUGE_VAL;
92 
        if(x==0.0) {
93 
            /* log(0) */
94 
            exc.type = SING;
95 
            if (_LIB_VERSION == _POSIX_)
96 
               errno = ERANGE;
97 
            else if (!matherr(&exc)) {
98 
               errno = ERANGE;
99 
            }
100 
        } else {
101 
            /* log(x<0) */
102 
            exc.type = DOMAIN;
103 
            if (_LIB_VERSION == _POSIX_)
104 
               errno = EDOM;
105 
            else if (!matherr(&exc)) {
106 
               errno = EDOM;
107 
            }
108 
            exc.retval = nan("");
109 
        }
110 
        if (exc.err != 0)
111 
           errno = exc.err;
112 
        return exc.retval;
113 
#endif
114 
}
115 
 
116 
#endif /* defined(_DOUBLE_IS_32BITS) */

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.