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tamaas/src/core/statistics.cpp
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statistics.cpp
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/**
* @file
*
* @author Guillaume Anciaux <guillaume.anciaux@epfl.ch>
* @author Lucas Frérot <lucas.frerot@epfl.ch>
*
* @section LICENSE
*
* Copyright (©) 2016-2017 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 "statistics.hh"
#include "loop.hh"
#include "static_types.hh"
/* -------------------------------------------------------------------------- */
__BEGIN_TAMAAS__
template <UInt dim>
Real Statistics<dim>::computeSpectralRMSSlope(Grid<Real, dim> & surface) {
auto h_size = GridHermitian<Real, dim>::hermitianDimensions(surface.sizes());
auto wavevectors =
FFTransform<Real, dim>::template computeFrequencies<true>(h_size);
auto psd = computePowerSpectrum(surface);
auto end = wavevectors.end(dim);
Real rms_slope_mean = 0;
rms_slope_mean = Loop::stridedReduce<operation::plus>
([](StaticVector<Real, dim>&& q, Complex & psd_val) {
return q.l2squared() * psd_val.real();
}, wavevectors, psd);
rms_slope_mean /= wavevectors.getNbPoints(); // average
rms_slope_mean *= 2; // because we have a hermitian surface
return rms_slope_mean;
}
/* -------------------------------------------------------------------------- */
template <UInt dim>
GridHermitian<Real, dim>
Statistics<dim>::computePowerSpectrum(Grid<Real, dim> & surface) {
auto h_size = GridHermitian<Real, dim>::hermitianDimensions(surface.sizes());
GridHermitian<Real, dim> psd(h_size, surface.getNbComponents());
FFTPlanManager::get().createPlan(surface, psd).forwardTransform();
Real factor = surface.getNbPoints();
// Squaring the fourier transform of surface and normalizing
Loop::loop([&factor](Complex & c) {
c *= std::conj(c);
c /= factor*factor;
}, psd);
FFTPlanManager::get().destroyPlan(surface, psd);
return psd;
}
/* -------------------------------------------------------------------------- */
template <UInt dim>
Grid<Real, dim>
Statistics<dim>::computeAutocorrelation(Grid<Real, dim> & surface) {
Grid<Real, dim> acf(surface.sizes(), surface.getNbComponents());
auto psd = computePowerSpectrum(surface);
FFTPlanManager::get().createPlan(acf, psd).backwardTransform();
acf *= acf.getNbPoints();
FFTPlanManager::get().destroyPlan(acf, psd);
return acf;
}
/* -------------------------------------------------------------------------- */
template struct Statistics<1>;
template struct Statistics<2>;
__END_TAMAAS__
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