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

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Revision 2 - (show annotations)
Wed Aug 1 13:51:53 2007 UTC (12 years, 1 month ago) by siliconforks
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Initial import.

1 /* -*- 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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