s_cosl.c revision 221234 
1/*-
2 * Copyright (c) 2007 Steven G. Kargl
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice unmodified, this list of conditions, and the following
10 *    disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/lib/msun/src/s_cosl.c 221234 2011-04-29 23:13:43Z kargl $");
29
30/*
31 * Limited testing on pseudorandom numbers drawn within [-2e8:4e8] shows
32 * an accuracy of <= 0.7412 ULP.
33 */
34
35#include <float.h>
36
37#include "math.h"
38#define INLINE_REM_PIO2L
39#include "math_private.h"
40#if LDBL_MANT_DIG == 64
41#include "../ld80/e_rem_pio2l.h"
42#elif LDBL_MANT_DIG == 113
43#include "../ld128/e_rem_pio2l.h"
44#else
45#error "Unsupported long double format"
46#endif
47
48long double
49cosl(long double x)
50{
51	union IEEEl2bits z;
52	int e0;
53	long double y[2];
54	long double hi, lo;
55
56	z.e = x;
57	z.bits.sign = 0;
58
59	/* If x = +-0 or x is a subnormal number, then cos(x) = 1 */
60	if (z.bits.exp == 0)
61		return (1.0);
62
63	/* If x = NaN or Inf, then cos(x) = NaN. */
64	if (z.bits.exp == 32767)
65		return ((x - x) / (x - x));
66
67	/* Optimize the case where x is already within range. */
68	if (z.e < M_PI_4)
69		return (__kernel_cosl(z.e, 0));
70
71	e0 = __ieee754_rem_pio2l(x, y);
72	hi = y[0];
73	lo = y[1];
74
75	switch (e0 & 3) {
76	case 0:
77	    hi = __kernel_cosl(hi, lo);
78	    break;
79	case 1:
80	    hi = - __kernel_sinl(hi, lo, 1);
81	    break;
82	case 2:
83	    hi = - __kernel_cosl(hi, lo);
84	    break;
85	case 3:
86	    hi = __kernel_sinl(hi, lo, 1);
87	    break;
88	}
89
90	return (hi);
91}
92