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229 lines
7.2 KiB
C++
229 lines
7.2 KiB
C++
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/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./lib/qcd/action/pseudofermion/OneFlavourEvenOddRational.h
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Copyright (C) 2015
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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
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directory
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*************************************************************************************/
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/* END LEGAL */
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#ifndef QCD_PSEUDOFERMION_ONE_FLAVOUR_EVEN_ODD_RATIONAL_H
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#define QCD_PSEUDOFERMION_ONE_FLAVOUR_EVEN_ODD_RATIONAL_H
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namespace Grid {
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namespace QCD {
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///////////////////////////////////////
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// One flavour rational
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///////////////////////////////////////
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// S_f = chi^dag * N(Mpc^dag*Mpc)/D(Mpc^dag*Mpc) * chi
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//
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// Here, M is some operator
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// N and D makeup the rat. poly
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//
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template <class Impl>
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class OneFlavourEvenOddRationalPseudoFermionAction
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: public Action<typename Impl::GaugeField> {
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public:
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INHERIT_IMPL_TYPES(Impl);
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typedef OneFlavourRationalParams Params;
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Params param;
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MultiShiftFunction PowerHalf;
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MultiShiftFunction PowerNegHalf;
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MultiShiftFunction PowerQuarter;
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MultiShiftFunction PowerNegQuarter;
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private:
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FermionOperator<Impl> &FermOp; // the basic operator
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// NOT using "Nroots"; IroIro is -- perhaps later, but this wasn't good for us
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// historically
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// and hasenbusch works better
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FermionField PhiEven; // the pseudo fermion field for this trajectory
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FermionField PhiOdd; // the pseudo fermion field for this trajectory
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public:
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OneFlavourEvenOddRationalPseudoFermionAction(FermionOperator<Impl> &Op,
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Params &p)
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: FermOp(Op),
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PhiEven(Op.FermionRedBlackGrid()),
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PhiOdd(Op.FermionRedBlackGrid()),
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param(p) {
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AlgRemez remez(param.lo, param.hi, param.precision);
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// MdagM^(+- 1/2)
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std::cout << GridLogMessage << "Generating degree " << param.degree
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<< " for x^(1/2)" << std::endl;
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remez.generateApprox(param.degree, 1, 2);
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PowerHalf.Init(remez, param.tolerance, false);
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PowerNegHalf.Init(remez, param.tolerance, true);
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// MdagM^(+- 1/4)
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std::cout << GridLogMessage << "Generating degree " << param.degree
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<< " for x^(1/4)" << std::endl;
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remez.generateApprox(param.degree, 1, 4);
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PowerQuarter.Init(remez, param.tolerance, false);
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PowerNegQuarter.Init(remez, param.tolerance, true);
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};
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virtual std::string action_name(){return "OneFlavourEvenOddRationalPseudoFermionAction";}
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virtual std::string LogParameters(){
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std::stringstream sstream;
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sstream << GridLogMessage << "["<<action_name()<<"] Low :" << param.lo << std::endl;
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sstream << GridLogMessage << "["<<action_name()<<"] High :" << param.hi << std::endl;
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sstream << GridLogMessage << "["<<action_name()<<"] Max iterations :" << param.MaxIter << std::endl;
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sstream << GridLogMessage << "["<<action_name()<<"] Tolerance :" << param.tolerance << std::endl;
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sstream << GridLogMessage << "["<<action_name()<<"] Degree :" << param.degree << std::endl;
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sstream << GridLogMessage << "["<<action_name()<<"] Precision :" << param.precision << std::endl;
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return sstream.str();
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}
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virtual void refresh(const GaugeField &U, GridParallelRNG &pRNG) {
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// P(phi) = e^{- phi^dag (MpcdagMpc)^-1/2 phi}
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// = e^{- phi^dag (MpcdagMpc)^-1/4 (MpcdagMpc)^-1/4 phi}
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// Phi = MpcdagMpc^{1/4} eta
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//
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// P(eta) = e^{- eta^dag eta}
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//
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// e^{x^2/2 sig^2} => sig^2 = 0.5.
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//
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// So eta should be of width sig = 1/sqrt(2).
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RealD scale = std::sqrt(0.5);
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FermionField eta(FermOp.FermionGrid());
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FermionField etaOdd(FermOp.FermionRedBlackGrid());
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FermionField etaEven(FermOp.FermionRedBlackGrid());
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gaussian(pRNG, eta);
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eta = eta * scale;
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pickCheckerboard(Even, etaEven, eta);
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pickCheckerboard(Odd, etaOdd, eta);
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FermOp.ImportGauge(U);
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// mutishift CG
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SchurDifferentiableOperator<Impl> Mpc(FermOp);
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ConjugateGradientMultiShift<FermionField> msCG(param.MaxIter, PowerQuarter);
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msCG(Mpc, etaOdd, PhiOdd);
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//////////////////////////////////////////////////////
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// FIXME : Clover term not yet..
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//////////////////////////////////////////////////////
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assert(FermOp.ConstEE() == 1);
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PhiEven = zero;
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};
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//////////////////////////////////////////////////////
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// S = phi^dag (Mdag M)^-1/2 phi
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//////////////////////////////////////////////////////
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virtual RealD S(const GaugeField &U) {
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FermOp.ImportGauge(U);
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FermionField Y(FermOp.FermionRedBlackGrid());
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SchurDifferentiableOperator<Impl> Mpc(FermOp);
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ConjugateGradientMultiShift<FermionField> msCG(param.MaxIter,
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PowerNegQuarter);
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msCG(Mpc, PhiOdd, Y);
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RealD action = norm2(Y);
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std::cout << GridLogMessage << "Pseudofermion action FIXME -- is -1/4 "
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"solve or -1/2 solve faster??? "
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<< action << std::endl;
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return action;
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};
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//////////////////////////////////////////////////////
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// Need
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// dS_f/dU = chi^dag d[N/D] chi
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//
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// N/D is expressed as partial fraction expansion:
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//
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// a0 + \sum_k ak/(M^dagM + bk)
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//
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// d[N/D] is then
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//
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// \sum_k -ak [M^dagM+bk]^{-1} [ dM^dag M + M^dag dM ] [M^dag M +
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// bk]^{-1}
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//
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// Need
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// Mf Phi_k = [MdagM+bk]^{-1} Phi
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// Mf Phi = \sum_k ak [MdagM+bk]^{-1} Phi
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//
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// With these building blocks
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//
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// dS/dU = \sum_k -ak Mf Phi_k^dag [ dM^dag M + M^dag dM ] Mf
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// Phi_k
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// S = innerprodReal(Phi,Mf Phi);
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//////////////////////////////////////////////////////
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virtual void deriv(const GaugeField &U, GaugeField &dSdU) {
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const int Npole = PowerNegHalf.poles.size();
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std::vector<FermionField> MPhi_k(Npole, FermOp.FermionRedBlackGrid());
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FermionField X(FermOp.FermionRedBlackGrid());
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FermionField Y(FermOp.FermionRedBlackGrid());
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GaugeField tmp(FermOp.GaugeGrid());
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FermOp.ImportGauge(U);
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SchurDifferentiableOperator<Impl> Mpc(FermOp);
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ConjugateGradientMultiShift<FermionField> msCG(param.MaxIter, PowerNegHalf);
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msCG(Mpc, PhiOdd, MPhi_k);
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dSdU = zero;
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for (int k = 0; k < Npole; k++) {
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RealD ak = PowerNegHalf.residues[k];
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X = MPhi_k[k];
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Mpc.Mpc(X, Y);
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Mpc.MpcDeriv(tmp, Y, X);
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dSdU = dSdU + ak * tmp;
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Mpc.MpcDagDeriv(tmp, X, Y);
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dSdU = dSdU + ak * tmp;
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}
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// dSdU = Ta(dSdU);
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};
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};
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}
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}
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#endif
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