amath/src/cplex/cpow.c

67 lines
2.2 KiB
C

/*-
* Copyright (c) 2014-2018 Carsten Sonne Larsen <cs@innolan.net>
* Copyright (c) 2007 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software written by Stephen L. Moshier.
* It is redistributed by the NetBSD Foundation by permission of the author.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The original source code can be obtained from:
* http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libm/complex/cpow.c?rev=1.1
*
* Project homepage:
* https://amath.innolan.net
*
*/
#include "prim.h"
/**
* @brief Complex number raised to a power
*/
complex cpow(complex a, complex z)
{
complex w;
double x, y, r, theta, absa, arga;
x = creal(z);
y = cimag(z);
absa = cabs(a);
if (absa == 0.0)
{
return cpack(0.0, + 0.0);
}
arga = atan2(cimag(a), creal(a));
r = pow(absa, x);
theta = x * arga;
if (y != 0.0)
{
r = r * exp(-y * arga);
theta = theta + y * log(absa);
}
w = cpack(r * cos(theta), r * sin(theta));
return w;
}