/[jscoverage]/trunk/js/src/fdlibm/e_sinh.c
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Annotation of /trunk/js/src/fdlibm/e_sinh.c

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Wed Aug 1 13:51:53 2007 UTC (14 years, 11 months ago) by siliconforks
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Initial import.

1 siliconforks 2 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2     *
3     * ***** BEGIN LICENSE BLOCK *****
4     * Version: MPL 1.1/GPL 2.0/LGPL 2.1
5     *
6     * The contents of this file are subject to the Mozilla Public License Version
7     * 1.1 (the "License"); you may not use this file except in compliance with
8     * the License. You may obtain a copy of the License at
9     * http://www.mozilla.org/MPL/
10     *
11     * Software distributed under the License is distributed on an "AS IS" basis,
12     * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
13     * for the specific language governing rights and limitations under the
14     * License.
15     *
16     * The Original Code is Mozilla Communicator client code, released
17     * March 31, 1998.
18     *
19     * The Initial Developer of the Original Code is
20     * Sun Microsystems, Inc.
21     * Portions created by the Initial Developer are Copyright (C) 1998
22     * the Initial Developer. All Rights Reserved.
23     *
24     * Contributor(s):
25     *
26     * Alternatively, the contents of this file may be used under the terms of
27     * either of the GNU General Public License Version 2 or later (the "GPL"),
28     * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
29     * in which case the provisions of the GPL or the LGPL are applicable instead
30     * of those above. If you wish to allow use of your version of this file only
31     * under the terms of either the GPL or the LGPL, and not to allow others to
32     * use your version of this file under the terms of the MPL, indicate your
33     * decision by deleting the provisions above and replace them with the notice
34     * and other provisions required by the GPL or the LGPL. If you do not delete
35     * the provisions above, a recipient may use your version of this file under
36     * the terms of any one of the MPL, the GPL or the LGPL.
37     *
38     * ***** END LICENSE BLOCK ***** */
39    
40     /* @(#)e_sinh.c 1.3 95/01/18 */
41     /*
42     * ====================================================
43     * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
44     *
45     * Developed at SunSoft, a Sun Microsystems, Inc. business.
46     * Permission to use, copy, modify, and distribute this
47     * software is freely granted, provided that this notice
48     * is preserved.
49     * ====================================================
50     */
51    
52     /* __ieee754_sinh(x)
53     * Method :
54     * mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2
55     * 1. Replace x by |x| (sinh(-x) = -sinh(x)).
56     * 2.
57     * E + E/(E+1)
58     * 0 <= x <= 22 : sinh(x) := --------------, E=expm1(x)
59     * 2
60     *
61     * 22 <= x <= lnovft : sinh(x) := exp(x)/2
62     * lnovft <= x <= ln2ovft: sinh(x) := exp(x/2)/2 * exp(x/2)
63     * ln2ovft < x : sinh(x) := x*shuge (overflow)
64     *
65     * Special cases:
66     * sinh(x) is |x| if x is +INF, -INF, or NaN.
67     * only sinh(0)=0 is exact for finite x.
68     */
69    
70     #include "fdlibm.h"
71    
72     #ifdef __STDC__
73     static const double one = 1.0, shuge = 1.0e307;
74     #else
75     static double one = 1.0, shuge = 1.0e307;
76     #endif
77    
78     #ifdef __STDC__
79     double __ieee754_sinh(double x)
80     #else
81     double __ieee754_sinh(x)
82     double x;
83     #endif
84     {
85     fd_twoints u;
86     double t,w,h;
87     int ix,jx;
88     unsigned lx;
89    
90     /* High word of |x|. */
91     u.d = x;
92     jx = __HI(u);
93     ix = jx&0x7fffffff;
94    
95     /* x is INF or NaN */
96     if(ix>=0x7ff00000) return x+x;
97    
98     h = 0.5;
99     if (jx<0) h = -h;
100     /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
101     if (ix < 0x40360000) { /* |x|<22 */
102     if (ix<0x3e300000) /* |x|<2**-28 */
103     if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
104     t = fd_expm1(fd_fabs(x));
105     if(ix<0x3ff00000) return h*(2.0*t-t*t/(t+one));
106     return h*(t+t/(t+one));
107     }
108    
109     /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
110     if (ix < 0x40862E42) return h*__ieee754_exp(fd_fabs(x));
111    
112     /* |x| in [log(maxdouble), overflowthresold] */
113     lx = *( (((*(unsigned*)&one)>>29)) + (unsigned*)&x);
114     if (ix<0x408633CE || (ix==0x408633ce)&&(lx<=(unsigned)0x8fb9f87d)) {
115     w = __ieee754_exp(0.5*fd_fabs(x));
116     t = h*w;
117     return t*w;
118     }
119    
120     /* |x| > overflowthresold, sinh(x) overflow */
121     return x*shuge;
122     }

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