/[jscoverage]/trunk/js/src/fdlibm/s_asinh.c
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Annotation of /trunk/js/src/fdlibm/s_asinh.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     /* @(#)s_asinh.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     /* asinh(x)
53     * Method :
54     * Based on
55     * asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]
56     * we have
57     * asinh(x) := x if 1+x*x=1,
58     * := sign(x)*(log(x)+ln2)) for large |x|, else
59     * := sign(x)*log(2|x|+1/(|x|+sqrt(x*x+1))) if|x|>2, else
60     * := sign(x)*log1p(|x| + x^2/(1 + sqrt(1+x^2)))
61     */
62    
63     #include "fdlibm.h"
64    
65     #ifdef __STDC__
66     static const double
67     #else
68     static double
69     #endif
70     one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
71     ln2 = 6.93147180559945286227e-01, /* 0x3FE62E42, 0xFEFA39EF */
72     really_big= 1.00000000000000000000e+300;
73    
74     #ifdef __STDC__
75     double fd_asinh(double x)
76     #else
77     double fd_asinh(x)
78     double x;
79     #endif
80     {
81     fd_twoints u;
82     double t,w;
83     int hx,ix;
84     u.d = x;
85     hx = __HI(u);
86     ix = hx&0x7fffffff;
87     if(ix>=0x7ff00000) return x+x; /* x is inf or NaN */
88     if(ix< 0x3e300000) { /* |x|<2**-28 */
89     if(really_big+x>one) return x; /* return x inexact except 0 */
90     }
91     if(ix>0x41b00000) { /* |x| > 2**28 */
92     w = __ieee754_log(fd_fabs(x))+ln2;
93     } else if (ix>0x40000000) { /* 2**28 > |x| > 2.0 */
94     t = fd_fabs(x);
95     w = __ieee754_log(2.0*t+one/(fd_sqrt(x*x+one)+t));
96     } else { /* 2.0 > |x| > 2**-28 */
97     t = x*x;
98     w =fd_log1p(fd_fabs(x)+t/(one+fd_sqrt(one+t)));
99     }
100     if(hx>0) return w; else return -w;
101     }

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