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_cos(double x);
35*25c28e83SPiotr Jasiukajtis * kernel (float) cos 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 * C(x) = (C0 + C1*z + C2*z*z) * (C3 + C4*z + z*z)
40*25c28e83SPiotr Jasiukajtis * where
41*25c28e83SPiotr Jasiukajtis * C0 = 1.09349482127188401868272000389539985058873853699e-0003
42*25c28e83SPiotr Jasiukajtis * C1 = -5.03324285989964979398034700054920226866107675091e-0004
43*25c28e83SPiotr Jasiukajtis * C2 = 2.43792880266971107750418061559602239831538067410e-0005
44*25c28e83SPiotr Jasiukajtis * C3 = 9.14499072605666582228127405245558035523741471271e+0002
45*25c28e83SPiotr Jasiukajtis * C4 = -3.63151270591815439197122504991683846785293207730e+0001
46*25c28e83SPiotr Jasiukajtis *
47*25c28e83SPiotr Jasiukajtis * The remez error is bound by |cos(x) - C(x)| < 2**(-34.2)
48*25c28e83SPiotr Jasiukajtis *
49*25c28e83SPiotr Jasiukajtis * Constants:
50*25c28e83SPiotr Jasiukajtis * The hexadecimal values are the intended ones for the following constants.
51*25c28e83SPiotr Jasiukajtis * The decimal values may be used, provided that the compiler will convert
52*25c28e83SPiotr Jasiukajtis * from decimal to binary accurately enough to produce the hexadecimal values
53*25c28e83SPiotr Jasiukajtis * shown.
54*25c28e83SPiotr Jasiukajtis */
55*25c28e83SPiotr Jasiukajtis /* INDENT ON */
56*25c28e83SPiotr Jasiukajtis
57*25c28e83SPiotr Jasiukajtis static const double q[] = {
58*25c28e83SPiotr Jasiukajtis /* C0 = */ 1.09349482127188401868272000389539985058873853699e-0003,
59*25c28e83SPiotr Jasiukajtis /* C1 = */ -5.03324285989964979398034700054920226866107675091e-0004,
60*25c28e83SPiotr Jasiukajtis /* C2 = */ 2.43792880266971107750418061559602239831538067410e-0005,
61*25c28e83SPiotr Jasiukajtis /* C3 = */ 9.14499072605666582228127405245558035523741471271e+0002,
62*25c28e83SPiotr Jasiukajtis /* C4 = */ -3.63151270591815439197122504991683846785293207730e+0001,
63*25c28e83SPiotr Jasiukajtis };
64*25c28e83SPiotr Jasiukajtis
65*25c28e83SPiotr Jasiukajtis #define C0 q[0]
66*25c28e83SPiotr Jasiukajtis #define C1 q[1]
67*25c28e83SPiotr Jasiukajtis #define C2 q[2]
68*25c28e83SPiotr Jasiukajtis #define C3 q[3]
69*25c28e83SPiotr Jasiukajtis #define C4 q[4]
70*25c28e83SPiotr Jasiukajtis
71*25c28e83SPiotr Jasiukajtis float
__k_cosf(double x)72*25c28e83SPiotr Jasiukajtis __k_cosf(double x) {
73*25c28e83SPiotr Jasiukajtis float ft;
74*25c28e83SPiotr Jasiukajtis double z;
75*25c28e83SPiotr Jasiukajtis int hx;
76*25c28e83SPiotr Jasiukajtis
77*25c28e83SPiotr Jasiukajtis hx = ((int *) &x)[HIWORD]; /* hx = leading x */
78*25c28e83SPiotr Jasiukajtis if ((hx & ~0x80000000) < 0x3f100000) { /* |x| < 2**-14 */
79*25c28e83SPiotr Jasiukajtis ft = (float) 1;
80*25c28e83SPiotr Jasiukajtis if (((int) x) == 0) /* raise inexact if x != 0 */
81*25c28e83SPiotr Jasiukajtis return (ft);
82*25c28e83SPiotr Jasiukajtis }
83*25c28e83SPiotr Jasiukajtis z = x * x;
84*25c28e83SPiotr Jasiukajtis ft = (float) (((C0 + z * C1) + (z * z) * C2) * (C3 + z * (C4 + z)));
85*25c28e83SPiotr Jasiukajtis return (ft);
86*25c28e83SPiotr Jasiukajtis }
87