1 /* $NetBSD: cpow.c,v 1.1 2007/08/20 16:01:35 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 <<cpow>>, <<cpowf>>---complex power
38
39 INDEX
40 cpow
41 INDEX
42 cpowf
43
44 SYNOPSIS
45 #include <complex.h>
46 double complex cpow(double complex <[x]>, double complex <[y]>);
47 float complex cpowf(float complex <[x]>, float complex <[y]>);
48
49
50 DESCRIPTION
51 @ifnottex
52 The cpow functions compute the complex power function x^y
53 power, with a branch cut for the first parameter along the
54 negative real axis.
55 @end ifnottex
56 @tex
57 The cpow functions compute the complex power function $x^y$
58 power, with a branch cut for the first parameter along the
59 negative real axis.
60 @end tex
61
62 <<cpowf>> is identical to <<cpow>>, except that it performs
63 its calculations on <<floats complex>>.
64
65 RETURNS
66 The cpow functions return the complex power function value.
67
68 PORTABILITY
69 <<cpow>> and <<cpowf>> are ISO C99
70
71 QUICKREF
72 <<cpow>> and <<cpowf>> are ISO C99
73
74 */
75
76
77 #include <complex.h>
78 #include <math.h>
79
80 double complex
cpow(double complex a,double complex z)81 cpow(double complex a, double complex z)
82 {
83 double complex w;
84 double x, y, r, theta, absa, arga;
85
86 x = creal(z);
87 y = cimag(z);
88 absa = cabs(a);
89 if (absa == 0.0) {
90 return (0.0 + 0.0 * (double complex) I);
91 }
92 arga = carg(a);
93 r = pow(absa, x);
94 theta = x * arga;
95 if (y != 0.0) {
96 r = r * exp(-y * arga);
97 theta = theta + y * log(absa);
98 }
99 w = r * cos(theta) + (r * sin(theta)) * (double complex) I;
100 return w;
101 }
102
