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110 lines
2.9 KiB
C++
110 lines
2.9 KiB
C++
#ifndef GRID_CONJUGATE_GRADIENT_H
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#define GRID_CONJUGATE_GRADIENT_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 ConjugateGradient : 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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ConjugateGradient(RealD tol,Integer maxit) : Tolerance(tol), MaxIterations(maxit) {
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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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psi.checkerboard = src.checkerboard;
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conformable(psi,src);
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RealD cp,c,a,d,b,ssq,qq,b_pred;
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Field p(src);
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Field mmp(src);
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Field r(src);
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//Initial residual computation & set up
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RealD guess = norm2(psi);
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Linop.HermOpAndNorm(psi,mmp,d,b);
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r= src-mmp;
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p= r;
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a =norm2(p);
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cp =a;
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ssq=norm2(src);
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if ( verbose ) {
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std::cout <<std::setprecision(4)<< "ConjugateGradient: guess "<<guess<<std::endl;
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std::cout <<std::setprecision(4)<< "ConjugateGradient: src "<<ssq <<std::endl;
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std::cout <<std::setprecision(4)<< "ConjugateGradient: mp "<<d <<std::endl;
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std::cout <<std::setprecision(4)<< "ConjugateGradient: mmp "<<b <<std::endl;
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std::cout <<std::setprecision(4)<< "ConjugateGradient: cp,r "<<cp <<std::endl;
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std::cout <<std::setprecision(4)<< "ConjugateGradient: p "<<a <<std::endl;
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}
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RealD rsq = Tolerance* Tolerance*ssq;
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//Check if guess is really REALLY good :)
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if ( cp <= rsq ) {
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return;
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}
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if(verbose) std::cout << std::setprecision(4)<< "ConjugateGradient: k=0 residual "<<cp<<" rsq"<<rsq<<std::endl;
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int k;
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for (k=1;k<=MaxIterations;k++){
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c=cp;
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Linop.HermOpAndNorm(p,mmp,d,qq);
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RealD qqck = norm2(mmp);
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ComplexD dck = innerProduct(p,mmp);
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a = c/d;
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b_pred = a*(a*qq-d)/c;
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cp = axpy_norm(r,-a,mmp,r);
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b = cp/c;
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// Fuse these loops ; should be really easy
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psi= a*p+psi;
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p = p*b+r;
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if (verbose) std::cout<<"ConjugateGradient: Iteration " <<k<<" residual "<<cp<< " target"<< rsq<<std::endl;
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// Stopping condition
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if ( cp <= rsq ) {
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Linop.HermOpAndNorm(psi,mmp,d,qq);
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p=mmp-src;
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RealD mmpnorm = sqrt(norm2(mmp));
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RealD psinorm = sqrt(norm2(psi));
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RealD srcnorm = sqrt(norm2(src));
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RealD resnorm = sqrt(norm2(p));
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RealD true_residual = resnorm/srcnorm;
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std::cout<<"ConjugateGradient: Converged on iteration " <<k
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<<" computed residual "<<sqrt(cp/ssq)
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<<" true residual "<<true_residual
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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<<"ConjugateGradient 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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