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135 lines
4.3 KiB
C++
135 lines
4.3 KiB
C++
/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./tests/Test_rect_force.cc
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Copyright (C) 2015
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Author: Azusa Yamaguchi <ayamaguc@staffmail.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 std;
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using namespace Grid;
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using namespace Grid::QCD;
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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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std::vector<int> latt_size = GridDefaultLatt();
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std::vector<int> simd_layout = GridDefaultSimd(Nd,vComplex::Nsimd());
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std::vector<int> mpi_layout = GridDefaultMpi();
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GridCartesian Grid(latt_size,simd_layout,mpi_layout);
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GridRedBlackCartesian RBGrid(&Grid);
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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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std::vector<int> seeds({1,2,3,4});
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GridParallelRNG pRNG(&Grid);
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pRNG.SeedFixedIntegers(std::vector<int>({45,12,81,9}));
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LatticeGaugeField U(&Grid);
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SU3::HotConfiguration(pRNG,U);
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double beta = 1.0;
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double c1 = -0.331;
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IwasakiGaugeActionR Action(beta);
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// PlaqPlusRectangleActionR Action(beta,c1);
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// WilsonGaugeActionR Action(beta);
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ComplexD S = Action.S(U);
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// get the deriv of phidag MdagM phi with respect to "U"
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LatticeGaugeField UdSdU(&Grid);
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Action.deriv(U,UdSdU);
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////////////////////////////////////
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// Modify the gauge field a little
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////////////////////////////////////
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RealD dt = 0.0001;
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LatticeColourMatrix mommu(&Grid);
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LatticeColourMatrix forcemu(&Grid);
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LatticeGaugeField mom(&Grid);
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LatticeGaugeField Uprime(&Grid);
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for(int mu=0;mu<Nd;mu++){
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SU3::GaussianFundamentalLieAlgebraMatrix(pRNG, mommu); // Traceless antihermitian momentum; gaussian in lie alg
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PokeIndex<LorentzIndex>(mom,mommu,mu);
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// fourth order exponential approx
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parallel_for(auto i=mom.begin();i<mom.end();i++){ // exp(pmu dt) * Umu
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Uprime[i](mu) = U[i](mu) + mom[i](mu)*U[i](mu)*dt
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+ mom[i](mu) *mom[i](mu) *U[i](mu)*(dt*dt/2.0)
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+ mom[i](mu) *mom[i](mu) *mom[i](mu) *U[i](mu)*(dt*dt*dt/6.0)
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+ mom[i](mu) *mom[i](mu) *mom[i](mu) *mom[i](mu) *U[i](mu)*(dt*dt*dt*dt/24.0)
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+ mom[i](mu) *mom[i](mu) *mom[i](mu) *mom[i](mu) *mom[i](mu) *U[i](mu)*(dt*dt*dt*dt*dt/120.0)
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+ mom[i](mu) *mom[i](mu) *mom[i](mu) *mom[i](mu) *mom[i](mu) *mom[i](mu) *U[i](mu)*(dt*dt*dt*dt*dt*dt/720.0);
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}
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}
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ComplexD Sprime = Action.S(Uprime);
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//////////////////////////////////////////////
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// Use derivative to estimate dS
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//////////////////////////////////////////////
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LatticeComplex dS(&Grid); dS = zero;
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for(int mu=0;mu<Nd;mu++){
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auto UdSdUmu = PeekIndex<LorentzIndex>(UdSdU,mu);
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mommu = PeekIndex<LorentzIndex>(mom,mu);
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// Update gauge action density
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// U = exp(p dt) U
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// dU/dt = p U
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// so dSdt = trace( dUdt dSdU) = trace( p UdSdUmu )
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dS = dS - trace(mommu*UdSdUmu)*dt*2.0;
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}
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ComplexD dSpred = sum(dS);
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std::cout << std::setprecision(15)<<std::endl;
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std::cout << GridLogMessage << " S "<<S<<std::endl;
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std::cout << GridLogMessage << " Sprime "<<Sprime<<std::endl;
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std::cout << GridLogMessage << "dS "<<Sprime-S<<std::endl;
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std::cout << GridLogMessage << "pred dS "<< dSpred <<std::endl;
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assert( fabs(real(Sprime-S-dSpred)) < 1.0e-2 ) ;
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std::cout<< GridLogMessage << "Done" <<std::endl;
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Grid_finalize();
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}
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