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Preconditioned conjugate residual

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Peter Boyle 2015-08-11 06:24:53 +01:00
parent 26f5ee0621
commit 9cd7f9ecad
1 changed files with 92 additions and 0 deletions
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lib/algorithms/iterative/PrecConjugateResidual.h Normal file
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#ifndef GRID_PREC_CONJUGATE_RESIDUAL_H
#define GRID_PREC_CONJUGATE_RESIDUAL_H
namespace Grid {
/////////////////////////////////////////////////////////////
// Base classes for iterative processes based on operators
// single input vec, single output vec.
/////////////////////////////////////////////////////////////
template<class Field>
class PrecConjugateResidual : public OperatorFunction<Field> {
public:
RealD Tolerance;
Integer MaxIterations;
int verbose;
LinearFunction<Field> &Preconditioner;
PrecConjugateResidual(RealD tol,Integer maxit,LinearFunction<Field> &Prec) : Tolerance(tol), MaxIterations(maxit), Preconditioner(Prec)
{
verbose=1;
};
void operator() (LinearOperatorBase<Field> &Linop,const Field &src, Field &psi){
RealD a, b, c, d;
RealD cp, ssq,rsq;
RealD rAr, rAAr, rArp;
RealD pAp, pAAp;
GridBase *grid = src._grid;
Field r(grid), p(grid), Ap(grid), Ar(grid), z(grid);
psi=zero;
r = src;
Preconditioner(r,p);
Linop.HermOpAndNorm(p,Ap,pAp,pAAp);
Ar=Ap;
rAr=pAp;
rAAr=pAAp;
cp =norm2(r);
ssq=norm2(src);
rsq=Tolerance*Tolerance*ssq;
if (verbose) std::cout<<GridLogMessage<<"PrecConjugateResidual: iteration " <<0<<" residual "<<cp<< " target"<< rsq<<std::endl;
for(int k=0;k<MaxIterations;k++){
Preconditioner(Ap,z);
RealD rq= real(innerProduct(Ap,z));
a = rAr/rq;
axpy(psi,a,p,psi);
cp = axpy_norm(r,-a,z,r);
rArp=rAr;
Linop.HermOpAndNorm(r,Ar,rAr,rAAr);
b =rAr/rArp;
axpy(p,b,p,r);
pAAp=axpy_norm(Ap,b,Ap,Ar);
if(verbose) std::cout<<GridLogMessage<<"PrecConjugateResidual: iteration " <<k<<" residual "<<cp<< " target"<< rsq<<std::endl;
if(cp<rsq) {
Linop.HermOp(psi,Ap);
axpy(r,-1.0,src,Ap);
RealD true_resid = norm2(r)/ssq;
std::cout<<GridLogMessage<<"PrecConjugateResidual: Converged on iteration " <<k
<< " computed residual "<<sqrt(cp/ssq)
<< " true residual "<<sqrt(true_resid)
<< " target " <<Tolerance <<std::endl;
return;
}
}
std::cout<<GridLogMessage<<"PrecConjugateResidual did NOT converge"<<std::endl;
assert(0);
}
};
}
#endif