1 /* $NetBSD: cacosh.c,v 1.2 2009/08/03 19:41:32 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 <<cacosh>>, <<cacoshf>>---complex arc hyperbolic cosine
38
39 INDEX
40 cacosh
41 INDEX
42 cacoshf
43
44 SYNOPSIS
45 #include <complex.h>
46 double complex cacosh(double complex <[z]>);
47 float complex cacoshf(float complex <[z]>);
48
49
50 DESCRIPTION
51 These functions compute the complex arc hyperbolic cosine of <[z]>,
52 with a branch cut at values less than 1 along the real axis.
53
54 <<cacoshf>> is identical to <<cacosh>>, except that it performs
55 its calculations on <<floats complex>>.
56
57 RETURNS
58 @ifnottex
59 These functions return the complex arc hyperbolic cosine value,
60 in the range of a half-strip of non-negative values along the
61 real axis and in the interval [-i * pi, +i * pi] along the
62 imaginary axis.
63 @end ifnottex
64 @tex
65 These functions return the complex arc hyperbolic cosine value,
66 in the range of a half-strip of non-negative values along the
67 real axis and in the interval [$-i\pi$, $+i\pi$] along the
68 imaginary axis.
69 @end tex
70
71 PORTABILITY
72 <<cacosh>> and <<cacoshf>> are ISO C99
73
74 QUICKREF
75 <<cacosh>> and <<cacoshf>> are ISO C99
76
77 */
78
79
80 #include <complex.h>
81
82 double complex
cacosh(double complex z)83 cacosh(double complex z)
84 {
85 double complex w;
86
87 #if 0 /* does not give the principal value */
88 w = (double complex) I * cacos(z);
89 #else
90 w = clog(z + csqrt(z + 1) * csqrt(z - 1));
91 #endif
92 return w;
93 }
94
