xref: /illumos-gate/usr/src/lib/libm/common/C/sin.c (revision fd75ca8de430ee0ba5ce650efee0ac0b85ed43e9)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
23  */
24 /*
25  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
26  * Use is subject to license terms.
27  */
28 
29 #pragma weak sin = __sin
30 
31 /* INDENT OFF */
32 /*
33  * sin(x)
34  * Accurate Table look-up algorithm by K.C. Ng, May, 1995.
35  *
36  * Algorithm: see sincos.c
37  */
38 
39 #include "libm.h"
40 
41 static const double sc[] = {
42 /* ONE	= */  1.0,
43 /* NONE	= */ -1.0,
44 /*
45  * |sin(x) - (x+pp1*x^3+pp2*x^5)| <= 2^-58.79 for |x| < 0.008
46  */
47 /* PP1	= */ -0.166666666666316558867252052378889521480627858683055567,
48 /* PP2	= */   .008333315652997472323564894248466758248475374977974017927,
49 /*
50  * |(sin(x) - (x+p1*x^3+...+p4*x^9)|
51  * |------------------------------ | <= 2^-57.63 for |x| < 0.1953125
52  * |                 x             |
53  */
54 /* P1  	= */ -1.666666666666629669805215138920301589656e-0001,
55 /* P2  	= */  8.333333332390951295683993455280336376663e-0003,
56 /* P3  	= */ -1.984126237997976692791551778230098403960e-0004,
57 /* P4  	= */  2.753403624854277237649987622848330351110e-0006,
58 /*
59  * |cos(x) - (1+qq1*x^2+qq2*x^4)| <= 2^-55.99 for |x| <= 0.008 (0x3f80624d)
60  */
61 /* QQ1	= */ -0.4999999999975492381842911981948418542742729,
62 /* QQ2	= */  0.041666542904352059294545209158357640398771740,
63 /* PI_H	= */  3.1415926535897931159979634685,
64 /* PI_L    = */  1.22464679914735317722606593227425e-16,
65 /* PI_L0   = */  1.22464679914558443311283879205095e-16,
66 /* PI_L1   = */  1.768744113227140223300005233735517376e-28,
67 /* PI2_H   = */  6.2831853071795862319959269370,
68 /* PI2_L   = */  2.44929359829470635445213186454850e-16,
69 /* PI2_L0  = */  2.44929359829116886622567758410190e-16,
70 /* PI2_L1  = */  3.537488226454280446600010467471034752e-28,
71 };
72 /* INDENT ON */
73 
74 #define	ONEA	sc
75 #define	ONE	sc[0]
76 #define	NONE	sc[1]
77 #define	PP1	sc[2]
78 #define	PP2	sc[3]
79 #define	P1	sc[4]
80 #define	P2	sc[5]
81 #define	P3	sc[6]
82 #define	P4	sc[7]
83 #define	QQ1	sc[8]
84 #define	QQ2	sc[9]
85 #define	PI_H	sc[10]
86 #define	PI_L	sc[11]
87 #define	PI_L0	sc[12]
88 #define	PI_L1	sc[13]
89 #define	PI2_H	sc[14]
90 #define	PI2_L	sc[15]
91 #define	PI2_L0	sc[16]
92 #define	PI2_L1	sc[17]
93 
94 extern const double  _TBL_sincos[], _TBL_sincosx[];
95 
96 double
97 sin(double x) {
98 	double	z, y[2], w, s, v, p, q;
99 	int	i, j, n, hx, ix, lx;
100 
101 	hx = ((int *)&x)[HIWORD];
102 	lx = ((int *)&x)[LOWORD];
103 	ix = hx & ~0x80000000;
104 
105 	if (ix <= 0x3fc50000) {	/* |x| < .1640625 */
106 		if (ix < 0x3e400000)	/* |x| < 2**-27 */
107 			if ((int)x == 0)
108 				return (x);
109 		z = x * x;
110 		if (ix < 0x3f800000)	/* |x| < 2**-8 */
111 			w = (z * x) * (PP1 + z * PP2);
112 		else
113 			w = (x * z) * ((P1 + z * P2) + (z * z) * (P3 + z * P4));
114 		return (x + w);
115 	}
116 
117 	/* for .1640625 < x < M, */
118 	n = ix >> 20;
119 	if (n < 0x402) {	/* x < 8 */
120 		i = (((ix >> 12) & 0xff) | 0x100) >> (0x401 - n);
121 		j = i - 10;
122 		x = fabs(x);
123 		v = x - _TBL_sincosx[j];
124 		if (((j - 181) ^ (j - 201)) < 0) {
125 			/* near pi, sin(x) = sin(pi-x) */
126 			p = PI_H - x;
127 			i = ix - 0x400921fb;
128 			x = p + PI_L;
129 			if ((i | ((lx - 0x54442D00) & 0xffffff00)) == 0) {
130 				/* very close to pi */
131 				x = p + PI_L0;
132 				return ((hx >= 0)? x + PI_L1 : -(x + PI_L1));
133 			}
134 			z = x * x;
135 			if (((ix - 0x40092000) >> 11) == 0) {
136 				/* |pi-x|<2**-8 */
137 				w = PI_L + (z * x) * (PP1 + z * PP2);
138 			} else {
139 				w = PI_L + (z * x) * ((P1 + z * P2) +
140 				    (z * z) * (P3 + z * P4));
141 			}
142 			return ((hx >= 0)? p + w : -p - w);
143 		}
144 		s = v * v;
145 		if (((j - 382) ^ (j - 402)) < 0) {
146 			/* near 2pi, sin(x) = sin(x-2pi) */
147 			p = x - PI2_H;
148 			i = ix - 0x401921fb;
149 			x = p - PI2_L;
150 			if ((i | ((lx - 0x54442D00) & 0xffffff00)) == 0) {
151 				/* very close to 2pi */
152 				x = p - PI2_L0;
153 				return ((hx >= 0)? x - PI2_L1 : -(x - PI2_L1));
154 			}
155 			z = x * x;
156 			if (((ix - 0x40192000) >> 10) == 0) {
157 				/* |x-2pi|<2**-8 */
158 				w = (z * x) * (PP1 + z * PP2) - PI2_L;
159 			} else {
160 				w = (z * x) * ((P1 + z * P2) +
161 				    (z * z) * (P3 + z * P4)) - PI2_L;
162 			}
163 			return ((hx >= 0)? p + w : -p - w);
164 		}
165 		j <<= 1;
166 		w = _TBL_sincos[j+1];
167 		z = _TBL_sincos[j];
168 		p = v + (v * s) * (PP1 + s * PP2);
169 		q = s * (QQ1 + s * QQ2);
170 		v = w * p + z * q;
171 		return ((hx >= 0)? z + v : -z - v);
172 	}
173 
174 	if (ix >= 0x7ff00000)	/* sin(Inf or NaN) is NaN */
175 		return (x / x);
176 
177 	/* argument reduction needed */
178 	n = __rem_pio2(x, y);
179 	switch (n & 3) {
180 	case 0:
181 		return (__k_sin(y[0], y[1]));
182 	case 1:
183 		return (__k_cos(y[0], y[1]));
184 	case 2:
185 		return (-__k_sin(y[0], y[1]));
186 	default:
187 		return (-__k_cos(y[0], y[1]));
188 	}
189 }
190