1 /* $NetBSD: s_tanl.c,v 1.3 2024/04/03 18:53:42 christos Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-2-Clause
5 *
6 * Copyright (c) 2007 Steven G. Kargl
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice unmodified, this list of conditions, and the following
14 * disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include <sys/cdefs.h>
32 __RCSID("$NetBSD: s_tanl.c,v 1.3 2024/04/03 18:53:42 christos Exp $");
33
34 /*
35 * Limited testing on pseudorandom numbers drawn within [0:4e8] shows
36 * an accuracy of <= 1.5 ULP where 247024 values of x out of 40 million
37 * possibles resulted in tan(x) that exceeded 0.5 ULP (ie., 0.6%).
38 */
39 #include "namespace.h"
40 #include <float.h>
41
42 #include "math.h"
43 #include "math_private.h"
44
45 #ifdef __weak_alias
__weak_alias(tanl,_tanl)46 __weak_alias(tanl, _tanl)
47 #endif
48
49 #ifdef __HAVE_LONG_DOUBLE
50
51 #if LDBL_MANT_DIG == 64
52 #include "../ld80/e_rem_pio2l.h"
53 #include "../ld80/k_tanl.c"
54 #elif LDBL_MANT_DIG == 113
55 #include "../ld128/e_rem_pio2l.h"
56 #include "../ld128/k_tanl.c"
57 #else
58 #error "Unsupported long double format"
59 #endif
60
61 long double
62 tanl(long double x)
63 {
64 union ieee_ext_u z;
65 int e0, s;
66 long double y[2];
67 long double hi, lo;
68
69 z.extu_ld = x;
70 s = z.extu_sign;
71 z.extu_sign = 0;
72
73 /* If x = +-0 or x is subnormal, then tan(x) = x. */
74 if (z.extu_exp == 0)
75 return (x);
76
77 /* If x = NaN or Inf, then tan(x) = NaN. */
78 if (z.extu_exp == 32767)
79 return ((x - x) / (x - x));
80
81 ENTERI();
82
83 /* Optimize the case where x is already within range. */
84 if (z.extu_ld < M_PI_4) {
85 hi = __kernel_tanl(z.extu_ld, 0, 0);
86 RETURNI(s ? -hi : hi);
87 }
88
89 e0 = __ieee754_rem_pio2l(x, y);
90 hi = y[0];
91 lo = y[1];
92
93 switch (e0 & 3) {
94 case 0:
95 case 2:
96 hi = __kernel_tanl(hi, lo, 0);
97 break;
98 case 1:
99 case 3:
100 hi = __kernel_tanl(hi, lo, 1);
101 break;
102 }
103
104 RETURNI(hi);
105 }
106
107 #else
108
109 long double
110 tanl(long double x)
111 {
112 return tan(x);
113 }
114
115 #endif
116