xref: /illumos-gate/usr/src/lib/libm/common/R/__sinf.c (revision 25c28e83)
1*25c28e83SPiotr Jasiukajtis /*
2*25c28e83SPiotr Jasiukajtis  * CDDL HEADER START
3*25c28e83SPiotr Jasiukajtis  *
4*25c28e83SPiotr Jasiukajtis  * The contents of this file are subject to the terms of the
5*25c28e83SPiotr Jasiukajtis  * Common Development and Distribution License (the "License").
6*25c28e83SPiotr Jasiukajtis  * You may not use this file except in compliance with the License.
7*25c28e83SPiotr Jasiukajtis  *
8*25c28e83SPiotr Jasiukajtis  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9*25c28e83SPiotr Jasiukajtis  * or http://www.opensolaris.org/os/licensing.
10*25c28e83SPiotr Jasiukajtis  * See the License for the specific language governing permissions
11*25c28e83SPiotr Jasiukajtis  * and limitations under the License.
12*25c28e83SPiotr Jasiukajtis  *
13*25c28e83SPiotr Jasiukajtis  * When distributing Covered Code, include this CDDL HEADER in each
14*25c28e83SPiotr Jasiukajtis  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15*25c28e83SPiotr Jasiukajtis  * If applicable, add the following below this CDDL HEADER, with the
16*25c28e83SPiotr Jasiukajtis  * fields enclosed by brackets "[]" replaced with your own identifying
17*25c28e83SPiotr Jasiukajtis  * information: Portions Copyright [yyyy] [name of copyright owner]
18*25c28e83SPiotr Jasiukajtis  *
19*25c28e83SPiotr Jasiukajtis  * CDDL HEADER END
20*25c28e83SPiotr Jasiukajtis  */
21*25c28e83SPiotr Jasiukajtis 
22*25c28e83SPiotr Jasiukajtis /*
23*25c28e83SPiotr Jasiukajtis  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
24*25c28e83SPiotr Jasiukajtis  */
25*25c28e83SPiotr Jasiukajtis /*
26*25c28e83SPiotr Jasiukajtis  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
27*25c28e83SPiotr Jasiukajtis  * Use is subject to license terms.
28*25c28e83SPiotr Jasiukajtis  */
29*25c28e83SPiotr Jasiukajtis 
30*25c28e83SPiotr Jasiukajtis #include "libm.h"
31*25c28e83SPiotr Jasiukajtis 
32*25c28e83SPiotr Jasiukajtis /* INDENT OFF */
33*25c28e83SPiotr Jasiukajtis /*
34*25c28e83SPiotr Jasiukajtis  * float __k_sin(double x);
35*25c28e83SPiotr Jasiukajtis  * kernel (float) sin function on [-pi/4, pi/4], pi/4 ~ 0.785398164
36*25c28e83SPiotr Jasiukajtis  * Input x is in double and assumed to be bounded by ~pi/4 in magnitude.
37*25c28e83SPiotr Jasiukajtis  *
38*25c28e83SPiotr Jasiukajtis  * Method: Let z = x * x, then
39*25c28e83SPiotr Jasiukajtis  *      S(x) = x(S0 + S1*z)(S2 + S3*z + z*z)
40*25c28e83SPiotr Jasiukajtis  * where
41*25c28e83SPiotr Jasiukajtis  *	S0 =   1.85735322054308378716204874632872525989806770558e-0003,
42*25c28e83SPiotr Jasiukajtis  *	S1 =  -1.95035094218403635082921458859320791358115801259e-0004,
43*25c28e83SPiotr Jasiukajtis  *	S2 =   5.38400550766074785970952495168558701485841707252e+0002,
44*25c28e83SPiotr Jasiukajtis  *	S3 =  -3.31975110777873728964197739157371509422022905947e+0001,
45*25c28e83SPiotr Jasiukajtis  *
46*25c28e83SPiotr Jasiukajtis  * The remez error is bound by  |(sin(x) - S(x))/x| < 2**(-28.2)
47*25c28e83SPiotr Jasiukajtis  *
48*25c28e83SPiotr Jasiukajtis  * Constants:
49*25c28e83SPiotr Jasiukajtis  * The hexadecimal values are the intended ones for the following constants.
50*25c28e83SPiotr Jasiukajtis  * The decimal values may be used, provided that the compiler will convert
51*25c28e83SPiotr Jasiukajtis  * from decimal to binary accurately enough to produce the hexadecimal values
52*25c28e83SPiotr Jasiukajtis  * shown.
53*25c28e83SPiotr Jasiukajtis  */
54*25c28e83SPiotr Jasiukajtis /* INDENT ON */
55*25c28e83SPiotr Jasiukajtis 
56*25c28e83SPiotr Jasiukajtis static const double q[] = {
57*25c28e83SPiotr Jasiukajtis /* S0 = */  1.85735322054308378716204874632872525989806770558e-0003,
58*25c28e83SPiotr Jasiukajtis /* S1 = */ -1.95035094218403635082921458859320791358115801259e-0004,
59*25c28e83SPiotr Jasiukajtis /* S2 = */  5.38400550766074785970952495168558701485841707252e+0002,
60*25c28e83SPiotr Jasiukajtis /* S3 = */ -3.31975110777873728964197739157371509422022905947e+0001,
61*25c28e83SPiotr Jasiukajtis };
62*25c28e83SPiotr Jasiukajtis 
63*25c28e83SPiotr Jasiukajtis #define	S0  q[0]
64*25c28e83SPiotr Jasiukajtis #define	S1  q[1]
65*25c28e83SPiotr Jasiukajtis #define	S2  q[2]
66*25c28e83SPiotr Jasiukajtis #define	S3  q[3]
67*25c28e83SPiotr Jasiukajtis 
68*25c28e83SPiotr Jasiukajtis float
__k_sinf(double x)69*25c28e83SPiotr Jasiukajtis __k_sinf(double x) {
70*25c28e83SPiotr Jasiukajtis 	float ft;
71*25c28e83SPiotr Jasiukajtis 	double z;
72*25c28e83SPiotr Jasiukajtis 	int hx;
73*25c28e83SPiotr Jasiukajtis 
74*25c28e83SPiotr Jasiukajtis 	hx = ((int *) &x)[HIWORD];	/* hx = leading x */
75*25c28e83SPiotr Jasiukajtis 	if ((hx & ~0x80000000) < 0x3f100000) {	/* if |x| < 2**-14 */
76*25c28e83SPiotr Jasiukajtis 		ft = (float) x;
77*25c28e83SPiotr Jasiukajtis 		if ((int) x == 0)	/* raise inexact if x != 0 */
78*25c28e83SPiotr Jasiukajtis 			return (ft);
79*25c28e83SPiotr Jasiukajtis 	}
80*25c28e83SPiotr Jasiukajtis 	z = x * x;
81*25c28e83SPiotr Jasiukajtis 	ft = (float) ((x * (S0 + z * S1)) * (S2 + z * (S3 + z)));
82*25c28e83SPiotr Jasiukajtis 	return (ft);
83*25c28e83SPiotr Jasiukajtis }
84