1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
/* s_cosl.c -- long double version of s_sin.c.
* Conversion to long double by Jakub Jelinek, jj@ultra.linux.cz.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#include <config.h>
/* Specification. */
#include <math.h>
#if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
long double
cosl (long double x)
{
return cos (x);
}
#else
/* sinl(x)
* Return sine function of x.
*
* kernel function:
* __kernel_sinl ... sine function on [-pi/4,pi/4]
* __kernel_cosl ... cose function on [-pi/4,pi/4]
* __ieee754_rem_pio2l ... argument reduction routine
*
* Method.
* Let S,C and T denote the sin, cos and tan respectively on
* [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
* in [-pi/4 , +pi/4], and let n = k mod 4.
* We have
*
* n sin(x) cos(x) tan(x)
* ----------------------------------------------------------
* 0 S C T
* 1 C -S -1/T
* 2 -S -C T
* 3 -C S -1/T
* ----------------------------------------------------------
*
* Special cases:
* Let trig be any of sin, cos, or tan.
* trig(+-INF) is NaN, with signals;
* trig(NaN) is that NaN;
*
* Accuracy:
* TRIG(x) returns trig(x) nearly rounded
*/
# include "trigl.h"
long double
cosl (long double x)
{
long double y[2],z=0.0L;
int n;
/* cosl(NaN) is NaN */
if (isnanl (x))
return x;
/* |x| ~< pi/4 */
if (x >= -0.7853981633974483096156608458198757210492
&& x <= 0.7853981633974483096156608458198757210492)
return kernel_cosl(x, z);
/* cosl(Inf) is NaN, cosl(0) is 1 */
else if (x + x == x && x != 0.0)
return x - x; /* NaN */
/* argument reduction needed */
else
{
n = ieee754_rem_pio2l (x, y);
switch (n & 3)
{
case 0:
return kernel_cosl (y[0], y[1]);
case 1:
return -kernel_sinl (y[0], y[1], 1);
case 2:
return -kernel_cosl (y[0], y[1]);
default:
return kernel_sinl (y[0], y[1], 1);
}
}
}
#endif
#if 0
int
main (void)
{
printf ("%.16Lg\n", cosl (0.7853981633974483096156608458198757210492));
printf ("%.16Lg\n", cosl (0.7853981633974483096156608458198757210492 *29));
printf ("%.16Lg\n", cosl (0.7853981633974483096156608458198757210492 *2));
printf ("%.16Lg\n", cosl (0.7853981633974483096156608458198757210492 *30));
printf ("%.16Lg\n", cosl (0.7853981633974483096156608458198757210492 *4));
printf ("%.16Lg\n", cosl (0.7853981633974483096156608458198757210492 *32));
printf ("%.16Lg\n", cosl (0.7853981633974483096156608458198757210492 *2/3));
printf ("%.16Lg\n", cosl (0.7853981633974483096156608458198757210492 *4/3));
}
#endif
|
