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libmultiscale/src/math/hamming_window.hh
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hamming_window.hh
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/**
* @file hamming_window.hh
*
* @author Guillaume Anciaux <guillaume.anciaux@epfl.ch>
*
* @date Mon Jan 07 16:36:30 2013
*
* @brief This implements the hamming window
*
* @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/>.
*
*/
#ifndef __LIBMULTISCALE_HAMMING_WINDOW_HH__
#define __LIBMULTISCALE_HAMMING_WINDOW_HH__
/* -------------------------------------------------------------------------- */
#include "function_interface.hh"
#include <gsl/gsl_sf_bessel.h>
/* -------------------------------------------------------------------------- */
__BEGIN_LIBMULTISCALE__
/** Class Hammingwindow
*
* This class implements access to the hamming window function
* @f$ F(x) = 0.54 + 0.46 \cdot cos(\frac{\pi x}{L}) @f$
*
*/
#define coeff1 0.54
#define coeff2 0.46
class HammingWindow : public FunctionInterface {
/* ------------------------------------------------------------------------ */
/* Constructors/Destructors */
/* ------------------------------------------------------------------------ */
public:
HammingWindow(Real L) {
this->L = L;
phase = M_PI / L;
};
virtual ~HammingWindow(){};
/* ------------------------------------------------------------------------ */
/* Methods */
/* ------------------------------------------------------------------------ */
public:
template <UInt derivation_order> inline Real compute(Real x);
/* ------------------------------------------------------------------------ */
/* Accessors */
/* ------------------------------------------------------------------------ */
public:
/* ------------------------------------------------------------------------ */
/* Class Members */
/* ------------------------------------------------------------------------ */
private:
Real L;
Real phase;
};
/* -------------------------------------------------------------------------- */
template <UInt derivation_order> inline Real HammingWindow::compute(Real x) {
LM_FATAL("order " << derivation_order << "not defined yet");
return 0.0;
}
/* -------------------------------------------------------------------------- */
template <> inline Real HammingWindow::compute<0>(Real x) {
if (x < L) {
Real tmp = coeff2 * cos(phase * x);
return coeff1 + tmp;
}
return 0.0;
}
/* -------------------------------------------------------------------------- */
template <> inline Real HammingWindow::compute<1>(Real x) {
if (x < L)
return -coeff2 * sin(phase * x) * phase;
return 0.0;
}
/* -------------------------------------------------------------------------- */
template <> inline Real HammingWindow::compute<2>(Real x) {
if (x < L)
return -coeff2 * cos(phase * x) * phase * phase;
return 0.0;
}
/* -------------------------------------------------------------------------- */
template <> inline Real HammingWindow::compute<3>(Real x) {
if (x < L)
return coeff2 * sin(phase * x) * phase * phase * phase;
return 0.0;
}
/* -------------------------------------------------------------------------- */
__END_LIBMULTISCALE__
#undef coeff1
#undef coeff2
#endif /* __LIBMULTISCALE_HAMMING_WINDOW_HH__ */
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