1 /* $NetBSD: ctan.c,v 1.1 2007/08/20 16:01:37 drochner 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 * imported and modified include for newlib 2010/10/03
32 * Marco Atzeri <marco_atzeri@yahoo.it>
33 */
34
35 /*
36 FUNCTION
37 <<ctan>>, <<ctanf>>---complex tangent
38
39 INDEX
40 ctan
41 INDEX
42 ctanf
43
44 SYNOPSIS
45 #include <complex.h>
46 double complex ctan(double complex <[z]>);
47 float complex ctanf(float complex <[z]>);
48
49
50 DESCRIPTION
51 These functions compute the complex tangent of <[z]>.
52
53 <<ctanf>> is identical to <<ctan>>, except that it performs
54 its calculations on <<floats complex>>.
55
56 RETURNS
57 These functions return the complex tangent value.
58
59 PORTABILITY
60 <<ctan>> and <<ctanf>> are ISO C99
61
62 QUICKREF
63 <<ctan>> and <<ctanf>> are ISO C99
64
65 */
66
67
68 #include <complex.h>
69 #include <math.h>
70 #include "cephes_subr.h"
71
72 double complex
ctan(double complex z)73 ctan(double complex z)
74 {
75 double d;
76
77 d = cos(2.0 * creal(z)) + cosh(2.0 * cimag(z));
78
79 if (fabs(d) < 0.25)
80 d = _ctans(z);
81
82 if (d == 0.0) {
83 /* mtherr ("ctan", OVERFLOW); */
84 return HUGE_VAL + HUGE_VAL * (double complex) I;
85 }
86
87 return (double complex) (sin(2.0 * creal(z)) / d) + (sinh(2.0 * cimag(z)) / d) * (double complex) I;
88 }
89
