1 /* $NetBSD: casinl.c,v 1.1 2014/10/10 00:48:18 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2007 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software written by Stephen L. Moshier.
8 * It is redistributed by the NetBSD Foundation by permission of the author.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include "../src/namespace.h"
33 #include <complex.h>
34 #include <math.h>
35
36 #ifdef __weak_alias
__weak_alias(casinl,_casinl)37 __weak_alias(casinl, _casinl)
38 #endif
39
40 long double complex
41 casinl(long double complex z)
42 {
43 long double complex w;
44 long double complex ca, ct, zz, z2;
45 long double x, y;
46
47 x = creall(z);
48 y = cimagl(z);
49
50 #if 0 /* MD: test is incorrect, casin(>1) is defined */
51 if (y == 0.0L) {
52 if (fabsl(x) > 1.0L) {
53 w = M_PI_2L + 0.0L * I;
54 #if 0
55 mtherr ("casinl", DOMAIN);
56 #endif
57 } else {
58 w = asinl(x) + 0.0L * I;
59 }
60 return w;
61 }
62 #endif
63
64 /* Power series expansion */
65 /*
66 b = cabsl(z);
67 if( b < 0.125L )
68 {
69 z2.r = (x - y) * (x + y);
70 z2.i = 2.0L * x * y;
71
72 cn = 1.0L;
73 n = 1.0L;
74 ca.r = x;
75 ca.i = y;
76 sum.r = x;
77 sum.i = y;
78 do
79 {
80 ct.r = z2.r * ca.r - z2.i * ca.i;
81 ct.i = z2.r * ca.i + z2.i * ca.r;
82 ca.r = ct.r;
83 ca.i = ct.i;
84
85 cn *= n;
86 n += 1.0;
87 cn /= n;
88 n += 1.0;
89 b = cn/n;
90
91 ct.r *= b;
92 ct.i *= b;
93 sum.r += ct.r;
94 sum.i += ct.i;
95 b = fabsl(ct.r) + fabsl(ct.i);
96 }
97 while( b > MACHEPL );
98 w->r = sum.r;
99 w->i = sum.i;
100 return;
101 }
102 */
103
104
105 ca = x + y * I;
106 ct = ca * I;
107 /* sqrtl( 1 - z*z) */
108 /* cmull( &ca, &ca, &zz ) */
109 /*x * x - y * y */
110 zz = (x - y) * (x + y) + (2.0L * x * y) * I;
111
112 zz = 1.0L - creall(zz) - cimagl(zz) * I;
113 z2 = csqrtl(zz);
114
115 zz = ct + z2;
116 zz = clogl(zz);
117 /* multiply by 1/i = -i */
118 w = zz * (-1.0L * I);
119 return w;
120 }
121