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 /* 23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 24 */ 25 /* 26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 27 * Use is subject to license terms. 28 */ 29 30 #include "libm.h" 31 32 /* INDENT OFF */ 33 /* 34 * float __k_cos(double x); 35 * kernel (float) cos function on [-pi/4, pi/4], pi/4 ~ 0.785398164 36 * Input x is in double and assumed to be bounded by ~pi/4 in magnitude. 37 * 38 * Method: Let z = x * x, then 39 * C(x) = (C0 + C1*z + C2*z*z) * (C3 + C4*z + z*z) 40 * where 41 * C0 = 1.09349482127188401868272000389539985058873853699e-0003 42 * C1 = -5.03324285989964979398034700054920226866107675091e-0004 43 * C2 = 2.43792880266971107750418061559602239831538067410e-0005 44 * C3 = 9.14499072605666582228127405245558035523741471271e+0002 45 * C4 = -3.63151270591815439197122504991683846785293207730e+0001 46 * 47 * The remez error is bound by |cos(x) - C(x)| < 2**(-34.2) 48 * 49 * Constants: 50 * The hexadecimal values are the intended ones for the following constants. 51 * The decimal values may be used, provided that the compiler will convert 52 * from decimal to binary accurately enough to produce the hexadecimal values 53 * shown. 54 */ 55 /* INDENT ON */ 56 57 static const double q[] = { 58 /* C0 = */ 1.09349482127188401868272000389539985058873853699e-0003, 59 /* C1 = */ -5.03324285989964979398034700054920226866107675091e-0004, 60 /* C2 = */ 2.43792880266971107750418061559602239831538067410e-0005, 61 /* C3 = */ 9.14499072605666582228127405245558035523741471271e+0002, 62 /* C4 = */ -3.63151270591815439197122504991683846785293207730e+0001, 63 }; 64 65 #define C0 q[0] 66 #define C1 q[1] 67 #define C2 q[2] 68 #define C3 q[3] 69 #define C4 q[4] 70 71 float 72 __k_cosf(double x) { 73 float ft; 74 double z; 75 int hx; 76 77 hx = ((int *) &x)[HIWORD]; /* hx = leading x */ 78 if ((hx & ~0x80000000) < 0x3f100000) { /* |x| < 2**-14 */ 79 ft = (float) 1; 80 if (((int) x) == 0) /* raise inexact if x != 0 */ 81 return (ft); 82 } 83 z = x * x; 84 ft = (float) (((C0 + z * C1) + (z * z) * C2) * (C3 + z * (C4 + z))); 85 return (ft); 86 } 87