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compute_energydensity.cc
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/**
* @file compute_energydensity.cc
*
* @author Guillaume Anciaux <guillaume.anciaux@epfl.ch>
*
* @date Wed Jul 09 21:59:47 2014
*
* @brief This computes the spectral energy density for 1D models
*
* @section LICENSE
*
* Copyright (©) 2010-2011 EPFL (Ecole Polytechnique Fédérale de Lausanne)
* Laboratory (LSMS - Laboratoire de Simulation en Mécanique des Solides)
*
* LibMultiScale 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.
*
* LibMultiScale 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 LibMultiScale. If not, see <http://www.gnu.org/licenses/>.
*
*/
/* -------------------------------------------------------------------------- */
#include <complex>
#include <fftw3.h>
/* -------------------------------------------------------------------------- */
#include "compute_energydensity.hh"
#include "lib_continuum.hh"
#include "lib_dd.hh"
#include "lib_md.hh"
#include "lm_common.hh"
#include "ref_point_data.hh"
/* -------------------------------------------------------------------------- */
__BEGIN_LIBMULTISCALE__
/* -------------------------------------------------------------------------- */
ComputeEnergyDensity::ComputeEnergyDensity(const std::string &name)
: LMObject(name) {
shift_fft = 1.0;
}
/* -------------------------------------------------------------------------- */
ComputeEnergyDensity::~ComputeEnergyDensity() {}
template <typename Cont> void ComputeEnergyDensity::build(Cont &cont) {
if (cont.size() == 0)
LM_FATAL("there is nothing to compute");
if (Cont::Dim != 1)
LM_FATAL("this compute operates only on 1D models");
UInt nbDof = cont.size();
std::vector<std::complex<Real>> dos;
dos.resize(nbDof * 2);
std::complex<Real> zero = 0.;
dos.assign(nbDof * 2, zero);
UInt cpt = 0;
for (auto &&at : cont) {
dos[cpt] = at.velocity()[0];
++cpt;
}
std::vector<Real> power;
fftw_complex *in = (fftw_complex *)&dos[0];
fftw_plan p =
fftw_plan_dft_1d(nbDof * 2, in, in, FFTW_FORWARD, FFTW_ESTIMATE);
fftw_execute(p);
power.resize(nbDof);
for (UInt j = 0; j < nbDof; ++j) {
Real dw = norm(dos[j]);
power[j] = sqrt(dw) / nbDof;
}
fftw_destroy_plan(p);
this->clear();
LM_TOIMPLEMENT;
// cast_compute(this)->setDim(2);
this->getOutputAsArray().push_back(power[0]);
this->getOutputAsArray().push_back(0.0);
for (UInt i = 1; i < nbDof; ++i) {
Real pw = 2.0 * power[i];
Real k = i * 0.5 / nbDof / shift_fft;
this->getOutputAsArray().push_back(pw);
this->getOutputAsArray().push_back(k);
}
}
/* -------------------------------------------------------------------------- */
/* LMDESC ENERGY_DENSITY
This computes the energy per mode in the wavevector space
Warning: Currently, this works only in 1D.
*/
/* LMEXAMPLE */
void ComputeEnergyDensity::declareParams() {
/* LMKEYWORD SHIFT_FFT
This keyword is used to shift the wavenumber axis
by given value provided by the user.
*/
this->parseKeyword("SHIFT_FFT", shift_fft);
}
/* -------------------------------------------------------------------------- */
DECLARE_COMPUTE_MAKE_CALL(ComputeEnergyDensity)
__END_LIBMULTISCALE__

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