OpenCores
URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libjava/] [classpath/] [native/] [fdlibm/] [e_cosh.c] - Blame information for rev 774

Details | Compare with Previous | View Log

Line No. Rev Author Line
1 774 jeremybenn 
 
2 
/* @(#)e_cosh.c 1.3 95/01/18 */
3 
/*
4 
 * ====================================================
5 
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 
 *
7 
 * Developed at SunSoft, 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 
/* __ieee754_cosh(x)
15 
 * Method :
16 
 * mathematically cosh(x) if defined to be (exp(x)+exp(-x))/2
17 
 *      1. Replace x by |x| (cosh(x) = cosh(-x)).
18 
 *      2.
19 
 *                                                      [ exp(x) - 1 ]^2
20 
 *          0        <= x <= ln2/2  :  cosh(x) := 1 + -------------------
21 
 *                                                         2*exp(x)
22 
 *
23 
 *                                                exp(x) +  1/exp(x)
24 
 *          ln2/2    <= x <= 22     :  cosh(x) := -------------------
25 
 *                                                        2
26 
 *          22       <= x <= lnovft :  cosh(x) := exp(x)/2
27 
 *          lnovft   <= x <= ln2ovft:  cosh(x) := exp(x/2)/2 * exp(x/2)
28 
 *          ln2ovft  <  x           :  cosh(x) := huge*huge (overflow)
29 
 *
30 
 * Special cases:
31 
 *      cosh(x) is |x| if x is +INF, -INF, or NaN.
32 
 *      only cosh(0)=1 is exact for finite x.
33 
 */
34 
 
35 
#include "fdlibm.h"
36 
 
37 
#ifndef _DOUBLE_IS_32BITS
38 
 
39 
#ifdef __STDC__
40 
static const double one = 1.0, half=0.5, huge = 1.0e300;
41 
#else
42 
static double one = 1.0, half=0.5, huge = 1.0e300;
43 
#endif
44 
 
45 
#ifdef __STDC__
46 
        double __ieee754_cosh(double x)
47 
#else
48 
        double __ieee754_cosh(x)
49 
        double x;
50 
#endif
51 
{
52 
        double t,w;
53 
        int32_t ix;
54 
        uint32_t lx;
55 
 
56 
    /* High word of |x|. */
57 
        GET_HIGH_WORD(ix,x);
58 
        ix &= 0x7fffffff;
59 
 
60 
    /* x is INF or NaN */
61 
        if(ix>=0x7ff00000) return x*x;
62 
 
63 
    /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
64 
        if(ix<0x3fd62e43) {
65 
            t = expm1(fabs(x));
66 
            w = one+t;
67 
            if (ix<0x3c800000) return w;        /* cosh(tiny) = 1 */
68 
            return one+(t*t)/(w+w);
69 
        }
70 
 
71 
    /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
72 
        if (ix < 0x40360000) {
73 
                t = __ieee754_exp(fabs(x));
74 
                return half*t+half/t;
75 
        }
76 
 
77 
    /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
78 
        if (ix < 0x40862E42)  return half*__ieee754_exp(fabs(x));
79 
 
80 
    /* |x| in [log(maxdouble), overflowthresold] */
81 
        lx = *( (((*(unsigned*)&one)>>29)) + (unsigned*)&x);
82 
        if (ix<0x408633CE ||
83 
              (ix==0x408633ce)&&(lx<=(unsigned)0x8fb9f87d)) {
84 
            w = __ieee754_exp(half*fabs(x));
85 
            t = half*w;
86 
            return t*w;
87 
        }
88 
 
89 
    /* |x| > overflowthresold, cosh(x) overflow */
90 
        return huge*huge;
91 
}
92 
#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.