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139 lines
3.6 KiB
C++
139 lines
3.6 KiB
C++
/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./tests/Test_poisson_fft.cc
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Copyright (C) 2015
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Author: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
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Author: Peter Boyle <paboyle@ph.ed.ac.uk>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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See the full license in the file "LICENSE" in the top level distribution directory
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*************************************************************************************/
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/* END LEGAL */
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#include <Grid/Grid.h>
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using namespace Grid;
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;
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int main (int argc, char ** argv)
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{
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Grid_init(&argc,&argv);
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int threads = GridThread::GetThreads();
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std::cout<<GridLogMessage << "Grid is setup to use "<<threads<<" threads"<<std::endl;
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int N=128;
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int N2=64;
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int W=16;
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int D=8;
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std::vector<int> latt_size ({N,N});
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std::vector<int> simd_layout({vComplexD::Nsimd(),1});
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std::vector<int> mpi_layout ({1,1});
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int vol = 1;
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int nd = latt_size.size();
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for(int d=0;d<nd;d++){
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vol = vol * latt_size[d];
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}
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GridCartesian GRID(latt_size,simd_layout,mpi_layout);
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LatticeComplexD pos(&GRID);
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LatticeComplexD zz(&GRID);
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LatticeComplexD neg(&GRID);
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LatticeInteger coor(&GRID);
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LatticeComplexD Charge(&GRID);
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LatticeComplexD ChargeTilde(&GRID);
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LatticeComplexD V(&GRID);
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LatticeComplexD Vtilde(&GRID);
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pos = ComplexD(1.0,0.0);
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neg = -pos;
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zz = ComplexD(0.0,0.0);
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Charge=Zero();
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// Parallel plate capacitor
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{
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int mu=0;
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LatticeCoordinate(coor,mu);
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Charge=where(coor==Integer(N2-D),pos,zz);
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Charge=where(coor==Integer(N2+D),neg,Charge);
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}
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{
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int mu=1;
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LatticeCoordinate(coor,mu);
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Charge=where(coor<Integer(N2-W),zz,Charge);
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Charge=where(coor>Integer(N2+W),zz,Charge);
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}
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// std::cout << Charge <<std::endl;
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std::vector<LatticeComplexD> k(4,&GRID);
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LatticeComplexD ksq(&GRID);
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ksq=Zero();
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for(int mu=0;mu<nd;mu++) {
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Integer L=latt_size[mu];
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LatticeCoordinate(coor,mu);
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LatticeCoordinate(k[mu],mu);
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k[mu] = where ( coor > (L/2), k[mu]-L, k[mu]);
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// std::cout << k[mu]<<std::endl;
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RealD TwoPiL = M_PI * 2.0/ L;
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k[mu] = TwoPiL * k[mu];
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ksq = ksq + k[mu]*k[mu];
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}
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// D^2 V = - rho
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// ksq Vtilde = rhoTilde
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// Vtilde = rhoTilde/Ksq
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// Fix zero of potential : Vtilde(0) = 0;
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std::vector<int> zero_mode(nd,0);
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TComplexD Tone = ComplexD(1.0,0.0);
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pokeSite(Tone,ksq,zero_mode);
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// std::cout << "Charge\n" << Charge <<std::endl;
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FFT theFFT(&GRID);
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theFFT.FFT_all_dim(ChargeTilde,Charge,FFT::forward);
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// std::cout << "Rhotilde\n" << ChargeTilde <<std::endl;
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Vtilde = ChargeTilde / ksq;
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// std::cout << "Vtilde\n" << Vtilde <<std::endl;
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TComplexD Tzero = ComplexD(0.0,0.0);
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pokeSite(Tzero,Vtilde,zero_mode);
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theFFT.FFT_all_dim(V,Vtilde,FFT::backward);
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std::cout << "V\n" << V <<std::endl;
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Grid_finalize();
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}
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