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

Contents of /trunk/js/src/fdlibm/k_sin.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: 4241 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 /* @(#)k_sin.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 /* __kernel_sin( x, y, iy)
53 * kernel sin function on [-pi/4, pi/4], pi/4 ~ 0.7854
54 * Input x is assumed to be bounded by ~pi/4 in magnitude.
55 * Input y is the tail of x.
56 * Input iy indicates whether y is 0. (if iy=0, y assume to be 0).
57 *
58 * Algorithm
59 * 1. Since sin(-x) = -sin(x), we need only to consider positive x.
60 * 2. if x < 2^-27 (hx<0x3e400000 0), return x with inexact if x!=0.
61 * 3. sin(x) is approximated by a polynomial of degree 13 on
62 * [0,pi/4]
63 * 3 13
64 * sin(x) ~ x + S1*x + ... + S6*x
65 * where
66 *
67 * |sin(x) 2 4 6 8 10 12 | -58
68 * |----- - (1+S1*x +S2*x +S3*x +S4*x +S5*x +S6*x )| <= 2
69 * | x |
70 *
71 * 4. sin(x+y) = sin(x) + sin'(x')*y
72 * ~ sin(x) + (1-x*x/2)*y
73 * For better accuracy, let
74 * 3 2 2 2 2
75 * r = x *(S2+x *(S3+x *(S4+x *(S5+x *S6))))
76 * then 3 2
77 * sin(x) = x + (S1*x + (x *(r-y/2)+y))
78 */
79
80 #include "fdlibm.h"
81
82 #ifdef __STDC__
83 static const double
84 #else
85 static double
86 #endif
87 half = 5.00000000000000000000e-01, /* 0x3FE00000, 0x00000000 */
88 S1 = -1.66666666666666324348e-01, /* 0xBFC55555, 0x55555549 */
89 S2 = 8.33333333332248946124e-03, /* 0x3F811111, 0x1110F8A6 */
90 S3 = -1.98412698298579493134e-04, /* 0xBF2A01A0, 0x19C161D5 */
91 S4 = 2.75573137070700676789e-06, /* 0x3EC71DE3, 0x57B1FE7D */
92 S5 = -2.50507602534068634195e-08, /* 0xBE5AE5E6, 0x8A2B9CEB */
93 S6 = 1.58969099521155010221e-10; /* 0x3DE5D93A, 0x5ACFD57C */
94
95 #ifdef __STDC__
96 double __kernel_sin(double x, double y, int iy)
97 #else
98 double __kernel_sin(x, y, iy)
99 double x,y; int iy; /* iy=0 if y is zero */
100 #endif
101 {
102 fd_twoints u;
103 double z,r,v;
104 int ix;
105 u.d = x;
106 ix = __HI(u)&0x7fffffff; /* high word of x */
107 if(ix<0x3e400000) /* |x| < 2**-27 */
108 {if((int)x==0) return x;} /* generate inexact */
109 z = x*x;
110 v = z*x;
111 r = S2+z*(S3+z*(S4+z*(S5+z*S6)));
112 if(iy==0) return x+v*(S1+z*r);
113 else return x-((z*(half*y-v*r)-y)-v*S1);
114 }

  ViewVC Help
Powered by ViewVC 1.1.24