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 * ====================================================
13 #include <sys/cdefs.h>
14 __FBSDID("$FreeBSD$");
17 * Return cosine function of x.
20 * __kernel_sin ... sine function on [-pi/4,pi/4]
21 * __kernel_cos ... cosine function on [-pi/4,pi/4]
22 * __ieee754_rem_pio2 ... argument reduction routine
25 * Let S,C and T denote the sin, cos and tan respectively on
26 * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
27 * in [-pi/4 , +pi/4], and let n = k mod 4.
30 * n sin(x) cos(x) tan(x)
31 * ----------------------------------------------------------
36 * ----------------------------------------------------------
39 * Let trig be any of sin, cos, or tan.
40 * trig(+-INF) is NaN, with signals;
41 * trig(NaN) is that NaN;
44 * TRIG(x) returns trig(x) nearly rounded
50 #define INLINE_REM_PIO2
51 #include "math_private.h"
52 #include "e_rem_pio2.c"
65 if(ix <= 0x3fe921fb) {
66 if(ix<0x3e46a09e) /* if x < 2**-27 * sqrt(2) */
67 if(((int)x)==0) return 1.0; /* generate inexact */
68 return __kernel_cos(x,z);
71 /* cos(Inf or NaN) is NaN */
72 else if (ix>=0x7ff00000) return x-x;
74 /* argument reduction needed */
76 n = __ieee754_rem_pio2(x,y);
78 case 0: return __kernel_cos(y[0],y[1]);
79 case 1: return -__kernel_sin(y[0],y[1],1);
80 case 2: return -__kernel_cos(y[0],y[1]);
82 return __kernel_sin(y[0],y[1],1);
87 #if (LDBL_MANT_DIG == 53)
88 __weak_reference(cos, cosl);