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Import BiCGSTAB solvers and tests
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David Murphy
221
Grid/algorithms/iterative/BiCGSTAB.h
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221
Grid/algorithms/iterative/BiCGSTAB.h
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/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./lib/algorithms/iterative/BiCGSTAB.h
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Copyright (C) 2015
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Author: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
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Author: Peter Boyle <paboyle@ph.ed.ac.uk>
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Author: paboyle <paboyle@ph.ed.ac.uk>
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Author: juettner <juettner@soton.ac.uk>
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Author: David Murphy <djmurphy@mit.edu>
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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 GRID_BICGSTAB_H
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#define GRID_BICGSTAB_H
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NAMESPACE_BEGIN(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 BiCGSTAB : public OperatorFunction<Field>
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{
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public:
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using OperatorFunction<Field>::operator();
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bool ErrorOnNoConverge; // throw an assert when the CG fails to converge.
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// Defaults true.
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RealD Tolerance;
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Integer MaxIterations;
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Integer IterationsToComplete; //Number of iterations the CG took to finish. Filled in upon completion
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BiCGSTAB(RealD tol, Integer maxit, bool err_on_no_conv = true) :
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Tolerance(tol), MaxIterations(maxit), ErrorOnNoConverge(err_on_no_conv){};
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void operator()(LinearOperatorBase<Field>& Linop, const Field& src, Field& psi)
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{
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psi.Checkerboard() = src.Checkerboard();
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conformable(psi, src);
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RealD cp(0), rho(1), rho_prev(0), alpha(1), beta(0), omega(1);
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RealD a(0), bo(0), d(0), b(0), ssq(0), qq(0);
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Field p(src);
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Field r(src);
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Field rhat(src);
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Field v(src);
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Field s(src);
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Field t(src);
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Field h(src);
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v = Zero();
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p = Zero();
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// Initial residual computation & set up
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RealD guess = norm2(psi);
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assert(std::isnan(guess) == 0);
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Linop.HermOpAndNorm(psi, v, d, b);
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r = src - v;
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rhat = r;
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a = norm2(r);
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ssq = norm2(src);
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std::cout << GridLogIterative << std::setprecision(8) << "BiCGSTAB: guess " << guess << std::endl;
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std::cout << GridLogIterative << std::setprecision(8) << "BiCGSTAB: src " << ssq << std::endl;
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std::cout << GridLogIterative << std::setprecision(8) << "BiCGSTAB: mp " << b << std::endl;
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std::cout << GridLogIterative << std::setprecision(8) << "BiCGSTAB: r " << a << std::endl;
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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(a <= rsq){ return; }
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std::cout << GridLogIterative << std::setprecision(8) << "BiCGSTAB: k=0 residual " << a << " target " << rsq << std::endl;
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GridStopWatch LinalgTimer;
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GridStopWatch InnerTimer;
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GridStopWatch AxpyNormTimer;
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GridStopWatch LinearCombTimer;
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GridStopWatch MatrixTimer;
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GridStopWatch SolverTimer;
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SolverTimer.Start();
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int k;
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for (k = 1; k <= MaxIterations; k++)
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{
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rho_prev = rho;
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LinalgTimer.Start();
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InnerTimer.Start();
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ComplexD Crho = innerProduct(rhat,r);
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InnerTimer.Stop();
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rho = Crho.real();
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beta = (rho / rho_prev) * (alpha / omega);
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LinearCombTimer.Start();
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bo = beta * omega;
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auto p_v = p.View();
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auto r_v = r.View();
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auto v_v = v.View();
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accelerator_for(ss, p_v.size(), Field::vector_object::Nsimd(),{
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coalescedWrite(p_v[ss], beta*p_v(ss) - bo*v_v(ss) + r_v(ss));
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});
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LinearCombTimer.Stop();
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LinalgTimer.Stop();
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MatrixTimer.Start();
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Linop.HermOp(p,v);
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MatrixTimer.Stop();
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LinalgTimer.Start();
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InnerTimer.Start();
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ComplexD Calpha = innerProduct(rhat,v);
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InnerTimer.Stop();
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alpha = rho / Calpha.real();
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LinearCombTimer.Start();
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auto h_v = h.View();
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auto psi_v = psi.View();
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accelerator_for(ss, h_v.size(), Field::vector_object::Nsimd(),{
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coalescedWrite(h_v[ss], alpha*p_v(ss) + psi_v(ss));
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});
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auto s_v = s.View();
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accelerator_for(ss, s_v.size(), Field::vector_object::Nsimd(),{
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coalescedWrite(s_v[ss], -alpha*v_v(ss) + r_v(ss));
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});
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LinearCombTimer.Stop();
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LinalgTimer.Stop();
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MatrixTimer.Start();
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Linop.HermOp(s,t);
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MatrixTimer.Stop();
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LinalgTimer.Start();
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InnerTimer.Start();
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ComplexD Comega = innerProduct(t,s);
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InnerTimer.Stop();
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omega = Comega.real() / norm2(t);
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LinearCombTimer.Start();
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auto t_v = t.View();
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accelerator_for(ss, psi_v.size(), Field::vector_object::Nsimd(),{
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coalescedWrite(psi_v[ss], h_v(ss) + omega * s_v(ss));
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coalescedWrite(r_v[ss], -omega * t_v(ss) + s_v(ss));
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});
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LinearCombTimer.Stop();
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cp = norm2(r);
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LinalgTimer.Stop();
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std::cout << GridLogIterative << "BiCGSTAB: Iteration " << k << " residual " << sqrt(cp/ssq) << " target " << Tolerance << std::endl;
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// Stopping condition
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if(cp <= rsq)
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{
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SolverTimer.Stop();
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Linop.HermOpAndNorm(psi, v, d, qq);
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p = v - src;
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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 << GridLogMessage << "BiCGSTAB Converged on iteration " << k << std::endl;
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std::cout << GridLogMessage << "\tComputed residual " << sqrt(cp/ssq) << std::endl;
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std::cout << GridLogMessage << "\tTrue residual " << true_residual << std::endl;
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std::cout << GridLogMessage << "\tTarget " << Tolerance << std::endl;
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std::cout << GridLogMessage << "Time breakdown " << std::endl;
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std::cout << GridLogMessage << "\tElapsed " << SolverTimer.Elapsed() << std::endl;
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std::cout << GridLogMessage << "\tMatrix " << MatrixTimer.Elapsed() << std::endl;
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std::cout << GridLogMessage << "\tLinalg " << LinalgTimer.Elapsed() << std::endl;
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std::cout << GridLogMessage << "\tInner " << InnerTimer.Elapsed() << std::endl;
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std::cout << GridLogMessage << "\tAxpyNorm " << AxpyNormTimer.Elapsed() << std::endl;
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std::cout << GridLogMessage << "\tLinearComb " << LinearCombTimer.Elapsed() << std::endl;
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if(ErrorOnNoConverge){ assert(true_residual / Tolerance < 10000.0); }
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IterationsToComplete = k;
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return;
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}
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}
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std::cout << GridLogMessage << "BiCGSTAB did NOT converge" << std::endl;
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if(ErrorOnNoConverge){ assert(0); }
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IterationsToComplete = k;
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}
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};
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NAMESPACE_END(Grid);
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#endif
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