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

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

Parent Directory Parent Directory | Revision Log Revision Log


Revision 2 - (show annotations)
Wed Aug 1 13:51:53 2007 UTC (14 years, 9 months ago) by siliconforks
File MIME type: text/plain
File size: 3831 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 /* @(#)s_cos.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 /* cos(x)
53 * Return cosine function of x.
54 *
55 * kernel function:
56 * __kernel_sin ... sine function on [-pi/4,pi/4]
57 * __kernel_cos ... cosine function on [-pi/4,pi/4]
58 * __ieee754_rem_pio2 ... argument reduction routine
59 *
60 * Method.
61 * Let S,C and T denote the sin, cos and tan respectively on
62 * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
63 * in [-pi/4 , +pi/4], and let n = k mod 4.
64 * We have
65 *
66 * n sin(x) cos(x) tan(x)
67 * ----------------------------------------------------------
68 * 0 S C T
69 * 1 C -S -1/T
70 * 2 -S -C T
71 * 3 -C S -1/T
72 * ----------------------------------------------------------
73 *
74 * Special cases:
75 * Let trig be any of sin, cos, or tan.
76 * trig(+-INF) is NaN, with signals;
77 * trig(NaN) is that NaN;
78 *
79 * Accuracy:
80 * TRIG(x) returns trig(x) nearly rounded
81 */
82
83 #include "fdlibm.h"
84
85 #ifdef __STDC__
86 double fd_cos(double x)
87 #else
88 double fd_cos(x)
89 double x;
90 #endif
91 {
92 fd_twoints u;
93 double y[2],z=0.0;
94 int n, ix;
95
96 /* High word of x. */
97 u.d = x;
98 ix = __HI(u);
99
100 /* |x| ~< pi/4 */
101 ix &= 0x7fffffff;
102 if(ix <= 0x3fe921fb) return __kernel_cos(x,z);
103
104 /* cos(Inf or NaN) is NaN */
105 else if (ix>=0x7ff00000) return x-x;
106
107 /* argument reduction needed */
108 else {
109 n = __ieee754_rem_pio2(x,y);
110 switch(n&3) {
111 case 0: return __kernel_cos(y[0],y[1]);
112 case 1: return -__kernel_sin(y[0],y[1],1);
113 case 2: return -__kernel_cos(y[0],y[1]);
114 default:
115 return __kernel_sin(y[0],y[1],1);
116 }
117 }
118 }

  ViewVC Help
Powered by ViewVC 1.1.24