1 /* $NetBSD: catan.c,v 1.2 2011/07/03 06:45:24 mrg 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 #include <float.h>
36 #include "cephes_subr.h"
37
38 #ifdef __weak_alias
__weak_alias(catan,_catan)39 __weak_alias(catan, _catan)
40 #endif
41
42 #define MAXNUM DBL_MAX
43
44 double complex
45 catan(double complex z)
46 {
47 double complex w;
48 double a, t, x, x2, y;
49
50 x = creal(z);
51 y = cimag(z);
52
53 if ((x == 0.0) && (y > 1.0))
54 goto ovrf;
55
56 x2 = x * x;
57 a = 1.0 - x2 - (y * y);
58 if (a == 0.0)
59 goto ovrf;
60
61 t = 0.5 * atan2(2.0 * x, a);
62 w = _redupi(t);
63
64 t = y - 1.0;
65 a = x2 + (t * t);
66 if (a == 0.0)
67 goto ovrf;
68
69 t = y + 1.0;
70 a = (x2 + (t * t))/a;
71 w = w + (0.25 * log(a)) * I;
72 return w;
73
74 ovrf:
75 #if 0
76 mtherr ("catan", OVERFLOW);
77 #endif
78 w = MAXNUM + MAXNUM * I;
79 return w;
80 }
81