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muSpectre/src/fft/projection_finite_strain_fast.cc
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projection_finite_strain_fast.cc
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/**
* @file projection_finite_strain_fast.cc
*
* @author Till Junge <till.junge@epfl.ch>
*
* @date 12 Dec 2017
*
* @brief implementation for fast projection in finite strain
*
* Copyright © 2017 Till Junge
*
* µSpectre is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, either version 3, or (at
* your option) any later version.
*
* µSpectre 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with µSpectre; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "fft/projection_finite_strain_fast.hh"
#include "fft/fft_utils.hh"
#include "common/tensor_algebra.hh"
#include "common/iterators.hh"
namespace muSpectre {
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
ProjectionFiniteStrainFast<DimS, DimM>::
ProjectionFiniteStrainFast(FFTEngine_ptr engine, Rcoord lengths)
:Parent{std::move(engine), lengths, Formulation::finite_strain},
xiField{make_field<Proj_t>("Projection Operator",
this->projection_container)},
xis(xiField)
{
for (auto res: this->fft_engine->get_domain_resolutions()) {
if (res % 2 == 0) {
throw ProjectionError
("Only an odd number of gridpoints in each direction is supported");
}
}
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
void ProjectionFiniteStrainFast<DimS, DimM>::
initialise(FFT_PlanFlags flags) {
Parent::initialise(flags);
FFT_freqs<DimS> fft_freqs(this->fft_engine->get_domain_resolutions(),
this->domain_lengths);
for (auto && tup: akantu::zip(*this->fft_engine, this->xis)) {
const auto & ccoord = std::get<0> (tup);
auto & xi = std::get<1>(tup);
xi = fft_freqs.get_unit_xi(ccoord);
}
if (this->get_subdomain_locations() == Ccoord{}) {
this->xis[0].setZero();
}
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
void ProjectionFiniteStrainFast<DimS, DimM>::apply_projection(Field_t & field) {
Grad_map field_map{this->fft_engine->fft(field)};
Real factor = this->fft_engine->normalisation();
for (auto && tup: akantu::zip(this->xis, field_map)) {
auto & xi{std::get<0>(tup)};
auto & f{std::get<1>(tup)};
f = factor * ((f*xi).eval()*xi.transpose());
}
this->fft_engine->ifft(field);
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
Eigen::Map<Eigen::ArrayXXd> ProjectionFiniteStrainFast<DimS, DimM>::
get_operator() {
return this->xiField.dyn_eigen();
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
std::array<Dim_t, 2> ProjectionFiniteStrainFast<DimS, DimM>::
get_strain_shape() const {
return std::array<Dim_t, 2>{DimM, DimM};
}
/* ---------------------------------------------------------------------- */
template class ProjectionFiniteStrainFast<twoD, twoD>;
template class ProjectionFiniteStrainFast<threeD, threeD>;
} // muSpectre
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