/[jscoverage]/trunk/js/src/fdlibm/e_cosh.c
ViewVC logotype

Contents of /trunk/js/src/fdlibm/e_cosh.c

Parent Directory Parent Directory | Revision Log Revision Log


Revision 2 - (show annotations)
Wed Aug 1 13:51:53 2007 UTC (12 years, 1 month ago) by siliconforks
File MIME type: text/plain
File size: 4347 byte(s)
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_cosh.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_cosh(x)
53 * Method :
54 * mathematically cosh(x) if defined to be (exp(x)+exp(-x))/2
55 * 1. Replace x by |x| (cosh(x) = cosh(-x)).
56 * 2.
57 * [ exp(x) - 1 ]^2
58 * 0 <= x <= ln2/2 : cosh(x) := 1 + -------------------
59 * 2*exp(x)
60 *
61 * exp(x) + 1/exp(x)
62 * ln2/2 <= x <= 22 : cosh(x) := -------------------
63 * 2
64 * 22 <= x <= lnovft : cosh(x) := exp(x)/2
65 * lnovft <= x <= ln2ovft: cosh(x) := exp(x/2)/2 * exp(x/2)
66 * ln2ovft < x : cosh(x) := huge*huge (overflow)
67 *
68 * Special cases:
69 * cosh(x) is |x| if x is +INF, -INF, or NaN.
70 * only cosh(0)=1 is exact for finite x.
71 */
72
73 #include "fdlibm.h"
74
75 #ifdef _WIN32
76 #define huge myhuge
77 #endif
78
79 #ifdef __STDC__
80 static const double one = 1.0, half=0.5, really_big = 1.0e300;
81 #else
82 static double one = 1.0, half=0.5, really_big = 1.0e300;
83 #endif
84
85 #ifdef __STDC__
86 double __ieee754_cosh(double x)
87 #else
88 double __ieee754_cosh(x)
89 double x;
90 #endif
91 {
92 fd_twoints u;
93 double t,w;
94 int ix;
95 unsigned lx;
96
97 /* High word of |x|. */
98 u.d = x;
99 ix = __HI(u);
100 ix &= 0x7fffffff;
101
102 /* x is INF or NaN */
103 if(ix>=0x7ff00000) return x*x;
104
105 /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
106 if(ix<0x3fd62e43) {
107 t = fd_expm1(fd_fabs(x));
108 w = one+t;
109 if (ix<0x3c800000) return w; /* cosh(tiny) = 1 */
110 return one+(t*t)/(w+w);
111 }
112
113 /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
114 if (ix < 0x40360000) {
115 t = __ieee754_exp(fd_fabs(x));
116 return half*t+half/t;
117 }
118
119 /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
120 if (ix < 0x40862E42) return half*__ieee754_exp(fd_fabs(x));
121
122 /* |x| in [log(maxdouble), overflowthresold] */
123 lx = *( (((*(unsigned*)&one)>>29)) + (unsigned*)&x);
124 if (ix<0x408633CE ||
125 (ix==0x408633ce)&&(lx<=(unsigned)0x8fb9f87d)) {
126 w = __ieee754_exp(half*fd_fabs(x));
127 t = half*w;
128 return t*w;
129 }
130
131 /* |x| > overflowthresold, cosh(x) overflow */
132 return really_big*really_big;
133 }

  ViewVC Help
Powered by ViewVC 1.1.24