1 /* @(#)s_cos.c 5.1 93/09/24 */
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
10 * ====================================================
14 * Return cosine function of x.
17 * __kernel_sin ... sine function on [-pi/4,pi/4]
18 * __kernel_cos ... cosine function on [-pi/4,pi/4]
19 * __ieee754_rem_pio2 ... argument reduction routine
22 * Let S,C and T denote the sin, cos and tan respectively on
23 * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
24 * in [-pi/4 , +pi/4], and let n = k mod 4.
27 * n sin(x) cos(x) tan(x)
28 * ----------------------------------------------------------
33 * ----------------------------------------------------------
36 * Let trig be any of sin, cos, or tan.
37 * trig(+-INF) is NaN, with signals;
38 * trig(NaN) is that NaN;
41 * TRIG(x) returns trig(x) nearly rounded
45 #include "math_private.h"
58 if(ix <= 0x3fe921fb) return __kernel_cos(x,z);
60 /* cos(Inf or NaN) is NaN */
61 else if (ix>=0x7ff00000) return x-x;
63 /* argument reduction needed */
65 n = __ieee754_rem_pio2(x,y);
67 case 0: return __kernel_cos(y[0],y[1]);
68 case 1: return -__kernel_sin(y[0],y[1],1);
69 case 2: return -__kernel_cos(y[0],y[1]);
71 return __kernel_sin(y[0],y[1],1);