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120 lines
3.5 KiB
C++
120 lines
3.5 KiB
C++
/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./lib/algorithms/iterative/PrecConjugateResidual.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 directory
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*************************************************************************************/
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/* END LEGAL */
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#ifndef GRID_PREC_CONJUGATE_RESIDUAL_H
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#define GRID_PREC_CONJUGATE_RESIDUAL_H
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namespace Grid {
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/////////////////////////////////////////////////////////////
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// Base classes for iterative processes based on operators
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// single input vec, single output vec.
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/////////////////////////////////////////////////////////////
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template<class Field>
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class PrecConjugateResidual : public OperatorFunction<Field> {
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public:
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RealD Tolerance;
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Integer MaxIterations;
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int verbose;
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LinearFunction<Field> &Preconditioner;
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PrecConjugateResidual(RealD tol,Integer maxit,LinearFunction<Field> &Prec) : Tolerance(tol), MaxIterations(maxit), Preconditioner(Prec)
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{
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verbose=1;
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};
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void operator() (LinearOperatorBase<Field> &Linop,const Field &src, Field &psi){
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RealD a, b, c, d;
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RealD cp, ssq,rsq;
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RealD rAr, rAAr, rArp;
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RealD pAp, pAAp;
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GridBase *grid = src._grid;
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Field r(grid), p(grid), Ap(grid), Ar(grid), z(grid);
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psi=zero;
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r = src;
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Preconditioner(r,p);
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Linop.HermOpAndNorm(p,Ap,pAp,pAAp);
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Ar=Ap;
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rAr=pAp;
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rAAr=pAAp;
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cp =norm2(r);
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ssq=norm2(src);
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rsq=Tolerance*Tolerance*ssq;
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if (verbose) std::cout<<GridLogMessage<<"PrecConjugateResidual: iteration " <<0<<" residual "<<cp<< " target"<< rsq<<std::endl;
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for(int k=0;k<MaxIterations;k++){
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Preconditioner(Ap,z);
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RealD rq= real(innerProduct(Ap,z));
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a = rAr/rq;
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axpy(psi,a,p,psi);
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cp = axpy_norm(r,-a,z,r);
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rArp=rAr;
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Linop.HermOpAndNorm(r,Ar,rAr,rAAr);
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b =rAr/rArp;
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axpy(p,b,p,r);
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pAAp=axpy_norm(Ap,b,Ap,Ar);
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if(verbose) std::cout<<GridLogMessage<<"PrecConjugateResidual: iteration " <<k<<" residual "<<cp<< " target"<< rsq<<std::endl;
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if(cp<rsq) {
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Linop.HermOp(psi,Ap);
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axpy(r,-1.0,src,Ap);
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RealD true_resid = norm2(r)/ssq;
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std::cout<<GridLogMessage<<"PrecConjugateResidual: Converged on iteration " <<k
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<< " computed residual "<<sqrt(cp/ssq)
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<< " true residual "<<sqrt(true_resid)
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<< " target " <<Tolerance <<std::endl;
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return;
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}
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}
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std::cout<<GridLogMessage<<"PrecConjugateResidual did NOT converge"<<std::endl;
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assert(0);
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}
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};
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}
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#endif
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