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fftransform_fftw.cpp
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Mon, Jun 3, 10:59

fftransform_fftw.cpp
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/**
* @file
*
* @author Lucas Frérot <lucas.frerot@epfl.ch>
*
* @section LICENSE
*
* Copyright (©) 2016 EPFL (Ecole Polytechnique Fédérale de
* Lausanne) Laboratory (LSMS - Laboratoire de Simulation en Mécanique des
* Solides)
*
* Tamaas is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* Tamaas is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
* A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
* details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Tamaas. If not, see <http://www.gnu.org/licenses/>.
*
*/
/* -------------------------------------------------------------------------- */
#include "fftransform_fftw.hh"
#define TAMAAS_FFTW_FLAG FFTW_ESTIMATE
__BEGIN_TAMAAS__
template <typename T, UInt dim>
FFTransformFFTW<T, dim>::FFTransformFFTW(Grid<T, dim>& real,
GridHermitian<T, dim>& spectral)
: FFTransform<T, dim>(real, spectral), forward_plan(nullptr),
backward_plan(nullptr) {
TAMAAS_ASSERT(real.getNbComponents() == spectral.getNbComponents(),
"components for FFTW do not match");
// Data pointers
Real* in = this->real.getInternalData();
fftw_complex* out =
reinterpret_cast<fftw_complex*>(this->spectral.getInternalData());
int components = real.getNbComponents();
// fftw parameters
int rank = dim; // dimension of fft
int n[dim] = {0};
std::copy(real.sizes().begin(), real.sizes().end(),
n); // size of individual fft
int howmany = components; // how many fft to compute
int idist = 1, odist = 1; // components are next to each other in memory
int istride = real.getStrides().back() * components,
ostride = spectral.getStrides().back() * components;
int *inembed = nullptr, *onembed = nullptr; // row major
#if TAMAAS_FFTW_FLAG != FFTW_ESTIMATE
// backup the input
Grid<Real, dim> backup(real);
#endif
forward_plan =
fftw_plan_many_dft_r2c(rank, n, howmany, in, inembed, istride, idist, out,
onembed, ostride, odist, TAMAAS_FFTW_FLAG);
backward_plan =
fftw_plan_many_dft_c2r(rank, n, howmany, out, onembed, ostride, odist, in,
inembed, istride, idist, TAMAAS_FFTW_FLAG);
#if TAMAAS_FFTW_FLAG != FFTW_ESTIMATE
// restore the backup
real = backup;
#endif
}
/* -------------------------------------------------------------------------- */
template <typename T, UInt dim>
FFTransformFFTW<T, dim>::~FFTransformFFTW() {
fftw_destroy_plan(forward_plan);
fftw_destroy_plan(backward_plan);
}
/* -------------------------------------------------------------------------- */
template <typename T, UInt dim>
void FFTransformFFTW<T, dim>::forwardTransform() {
fftw_execute(forward_plan);
}
/* -------------------------------------------------------------------------- */
template <typename T, UInt dim>
void FFTransformFFTW<T, dim>::backwardTransform() {
fftw_execute(backward_plan);
this->normalize();
}
/* -------------------------------------------------------------------------- */
template class FFTransformFFTW<Real, 1>;
template class FFTransformFFTW<Real, 2>;
template class FFTransformFFTW<Real, 3>;
__END_TAMAAS__

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