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NFFT is a software library, written in C, for computing non-equispaced fast Fourier transforms and related variations. It implements the following transforms: 1. Non-equispaced fast Fourier transform (NFFT) - forward transform (NFFT), i.e. frequency to time/space domain - adjoint transform (adjoint NFFT), i.e. time/space to frequency domain 2. Generalisations - to arbitrary nodes in time and frequency domain (NNFFT) - to real-valued data, i.e. (co)sine transforms, (NFCT, NFST) - to the sphere S^2 (NFSFT) - to the rotation group (NFSOFT) - to the hyperbolic cross (NSFFT) 3. Generalised inverse transformations based on iterative methods, e.g. CGNR/CGNE PR: 223429 Submitted by: Michael Danilov <mike.d.ft402@gmail.com>
57 lines
2.0 KiB
C
57 lines
2.0 KiB
C
/* $NetBSD: cpow.c,v 1.1 2007/08/20 16:01:35 drochner Exp $ */
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/*-
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* Copyright (c) 2007 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software written by Stephen L. Moshier.
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* It is redistributed by the NetBSD Foundation by permission of the author.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <complex.h>
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#include <math.h>
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double complex
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cpow(double complex a, double complex z)
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{
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double complex w;
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double x, y, r, theta, absa, arga;
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x = creal(z);
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y = cimag(z);
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absa = cabs(a);
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if (absa == 0.0) {
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return (0.0 + 0.0 * I);
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}
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arga = carg(a);
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r = pow(absa, x);
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theta = x * arga;
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if (y != 0.0) {
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r = r * exp(-y * arga);
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theta = theta + y * log(absa);
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}
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w = r * cos(theta) + (r * sin(theta)) * I;
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return w;
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}
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