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/* $NetBSD: cpow.c,v 1.1 2007/08/20 16:01:35 drochner Exp $ */
/*-
* 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*
* imported and modified include for newlib 2010/10/03
* Marco Atzeri <marco_atzeri@yahoo.it>
*/
/*
FUNCTION
<<cpow>>, <<cpowf>>---complex power
INDEX
cpow
INDEX
cpowf
ANSI_SYNOPSIS
#include <complex.h>
double complex cpow(double complex <[x]>, double complex <[y]>);
float complex cpowf(float complex <[x]>, float complex <[y]>);
DESCRIPTION
@ifnottex
The cpow functions compute the complex power function x^y
power, with a branch cut for the first parameter along the
negative real axis.
@end ifnottex
@tex
The cpow functions compute the complex power function $x^y$
power, with a branch cut for the first parameter along the
negative real axis.
@end tex
<<cpowf>> is identical to <<cpow>>, except that it performs
its calculations on <<floats complex>>.
RETURNS
The cpow functions return the complex power function value.
PORTABILITY
<<cpow>> and <<cpowf>> are ISO C99
QUICKREF
<<cpow>> and <<cpowf>> are ISO C99
*/
#include <complex.h>
#include <math.h>
double complex
cpow(double complex a, double complex z)
{
double complex w;
double x, y, r, theta, absa, arga;
x = creal(z);
y = cimag(z);
absa = cabs(a);
if (absa == 0.0) {
return (0.0 + 0.0 * I);
}
arga = carg(a);
r = pow(absa, x);
theta = x * arga;
if (y != 0.0) {
r = r * exp(-y * arga);
theta = theta + y * log(absa);
}
w = r * cos(theta) + (r * sin(theta)) * I;
return w;
}
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