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 /* 31 * cosl(x) 32 * Table look-up algorithm by K.C. Ng, November, 1989. 33 * 34 * kernel function: 35 * __k_sinl ... sin function on [-pi/4,pi/4] 36 * __k_cosl ... cos function on [-pi/4,pi/4] 37 * __rem_pio2l ... argument reduction routine 38 * 39 * Method. 40 * Let S and C denote the sin and cos respectively on [-PI/4, +PI/4]. 41 * 1. Assume the argument x is reduced to y1+y2 = x-k*pi/2 in 42 * [-pi/2 , +pi/2], and let n = k mod 4. 43 * 2. Let S=S(y1+y2), C=C(y1+y2). Depending on n, we have 44 * 45 * n sin(x) cos(x) tan(x) 46 * ---------------------------------------------------------- 47 * 0 S C S/C 48 * 1 C -S -C/S 49 * 2 -S -C S/C 50 * 3 -C S -C/S 51 * ---------------------------------------------------------- 52 * 53 * Special cases: 54 * Let trig be any of sin, cos, or tan. 55 * trig(+-INF) is NaN, with signals; 56 * trig(NaN) is that NaN; 57 * 58 * Accuracy: 59 * computer TRIG(x) returns trig(x) nearly rounded. 60 */ 61 62 #pragma weak __cosl = cosl 63 64 #include "libm.h" 65 #include "longdouble.h" 66 67 long double 68 cosl(long double x) { 69 long double y[2], z = 0.0L; 70 int n, ix; 71 72 ix = *(int *) &x; /* High word of x */ 73 74 ix &= 0x7fffffff; 75 if (ix <= 0x3ffe9220) /* |x| ~< pi/4 */ 76 return (__k_cosl(x, z)); 77 else if (ix >= 0x7fff0000) /* trig(Inf or NaN) is NaN */ 78 return (x - x); 79 else { /* argument reduction needed */ 80 n = __rem_pio2l(x, y); 81 switch (n & 3) { 82 case 0: 83 return (__k_cosl(y[0], y[1])); 84 case 1: 85 return (-__k_sinl(y[0], y[1])); 86 case 2: 87 return (-__k_cosl(y[0], y[1])); 88 case 3: 89 return (__k_sinl(y[0], y[1])); 90 } 91 } 92 /* NOTREACHED */ 93 return 0.0L; 94 } 95