1/* s_cosl.c -- long double version of s_cos.c.
2 * Conversion to long double by Ulrich Drepper,
3 * Cygnus Support, drepper@cygnus.com.
4 */
5
6/*
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 *
10 * Developed at SunPro, a Sun Microsystems, Inc. business.
11 * Permission to use, copy, modify, and distribute this
12 * software is freely granted, provided that this notice
13 * is preserved.
14 * ====================================================
15 */
16
17#if defined(LIBM_SCCS) && !defined(lint)
18static char rcsid[] = "$NetBSD: $";
19#endif
20
21/* cosl(x)
22 * Return cosine function of x.
23 *
24 * kernel function:
25 * __kernel_sinl ... sine function on [-pi/4,pi/4]
26 * __kernel_cosl ... cosine function on [-pi/4,pi/4]
27 * __ieee754_rem_pio2l ... argument reduction routine
28 *
29 * Method.
30 * Let S,C and T denote the sin, cos and tan respectively on
31 * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
32 * in [-pi/4 , +pi/4], and let n = k mod 4.
33 * We have
34 *
35 * n sin(x) cos(x) tan(x)
36 * ----------------------------------------------------------
37 * 0 S C T
38 * 1 C -S -1/T
39 * 2 -S -C T
40 * 3 -C S -1/T
41 * ----------------------------------------------------------
42 *
43 * Special cases:
44 * Let trig be any of sin, cos, or tan.
45 * trig(+-INF) is NaN, with signals;
46 * trig(NaN) is that NaN;
47 *
48 * Accuracy:
49 * TRIG(x) returns trig(x) nearly rounded
50 */
51
52#include <errno.h>
53#include <math.h>
54#include <math_private.h>
55#include <libm-alias-ldouble.h>
56
57long double __cosl(long double x)
58{
59 long double y[2],z=0.0;
60 int32_t n, se, i0, i1;
61
62 /* High word of x. */
63 GET_LDOUBLE_WORDS(se,i0,i1,x);
64
65 /* |x| ~< pi/4 */
66 se &= 0x7fff;
67 if(se < 0x3ffe || (se == 0x3ffe && i0 <= 0xc90fdaa2))
68 return __kernel_cosl(x,z);
69
70 /* cos(Inf or NaN) is NaN */
71 else if (se==0x7fff) {
72 if (i1 == 0 && i0 == 0x80000000)
73 __set_errno (EDOM);
74 return x-x;
75 }
76
77 /* argument reduction needed */
78 else {
79 n = __ieee754_rem_pio2l(x,y);
80 switch(n&3) {
81 case 0: return __kernel_cosl(y[0],y[1]);
82 case 1: return -__kernel_sinl(y[0],y[1],1);
83 case 2: return -__kernel_cosl(y[0],y[1]);
84 default:
85 return __kernel_sinl(y[0],y[1],1);
86 }
87 }
88}
89libm_alias_ldouble (__cos, cos)
90