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muSpectre/src/fft/projection_small_strain.cc
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projection_small_strain.cc
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/**
* @file projection_small_strain.cc
*
* @author Till Junge <till.junge@altermail.ch>
*
* @date 14 Jan 2018
*
* @brief Implementation for ProjectionSmallStrain
*
* Copyright © 2018 Till Junge
*
* µSpectre 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, 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 Lesser 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.
*
* Additional permission under GNU GPL version 3 section 7
*
* If you modify this Program, or any covered work, by linking or combining it
* with proprietary FFT implementations or numerical libraries, containing parts
* covered by the terms of those libraries' licenses, the licensors of this
* Program grant you additional permission to convey the resulting work.
*/
#include "fft/projection_small_strain.hh"
#include "fft/fft_utils.hh"
namespace muSpectre {
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
ProjectionSmallStrain<DimS, DimM>::ProjectionSmallStrain(FFTEngine_ptr engine,
Rcoord lengths)
: Parent{std::move(engine), lengths, Formulation::small_strain} {
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 ProjectionSmallStrain<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->Ghat)) {
const auto & ccoord = std::get<0>(tup);
auto & G = std::get<1>(tup);
auto xi = fft_freqs.get_unit_xi(ccoord);
auto kron = [](const Dim_t i, const Dim_t j) -> Real {
return (i == j) ? 1. : 0.;
};
for (Dim_t i{0}; i < DimS; ++i) {
for (Dim_t j{0}; j < DimS; ++j) {
for (Dim_t l{0}; l < DimS; ++l) {
for (Dim_t m{0}; m < DimS; ++m) {
Real & g = get(G, i, j, l, m);
g = 0.5 *
(xi(i) * kron(j, l) * xi(m) + xi(i) * kron(j, m) * xi(l) +
xi(j) * kron(i, l) * xi(m) +
xi(j) * kron(i, m) * xi(l)) -
xi(i) * xi(j) * xi(l) * xi(m);
}
}
}
}
}
if (this->get_subdomain_locations() == Ccoord{}) {
this->Ghat[0].setZero();
}
}
template class ProjectionSmallStrain<twoD, twoD>;
template class ProjectionSmallStrain<threeD, threeD>;
} // namespace muSpectre
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