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GCRODR/PrecGCRODREpetraExFile.cpp

This is an example of how to use the Belos::GCRODRSolMgr solver manager with an Ifpack preconditioner.

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// Belos: Block Linear Solvers Package
// Copyright 2004 Sandia Corporation
//
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//
// This driver reads a problem from a file, which can be in Harwell-Boeing (*.hb),
// Matrix Market (*.mtx), or triplet format (*.triU, *.triS). The right-hand side
// from the problem, if it exists, will be used instead of multiple random
// right-hand-sides. The initial guesses are all set to zero. An ILU preconditioner
// is constructed using the Ifpack factory.
//
#include "BelosEpetraAdapter.hpp"
#include "BelosEpetraUtils.h"
#include "Ifpack_IlukGraph.h"
#include "Ifpack_CrsRiluk.h"
#include "Epetra_Map.h"
#ifdef EPETRA_MPI
#include "Epetra_MpiComm.h"
#else
#include "Epetra_SerialComm.h"
#endif
#include "Epetra_CrsMatrix.h"
#include "Teuchos_StandardCatchMacros.hpp"
int main(int argc, char *argv[]) {
//
int MyPID = 0;
#ifdef EPETRA_MPI
// Initialize MPI
MPI_Init(&argc,&argv);
Epetra_MpiComm Comm(MPI_COMM_WORLD);
MyPID = Comm.MyPID();
#else
#endif
//
typedef double ST;
typedef SCT::magnitudeType MT;
typedef Epetra_MultiVector MV;
typedef Epetra_Operator OP;
using Teuchos::RCP;
using Teuchos::rcp;
bool verbose = false;
bool success = true;
try {
bool proc_verbose = false;
bool debug = false;
bool leftprec = true; // left preconditioning or right.
int frequency = -1; // frequency of status test output.
int numrhs = 1; // number of right-hand sides to solve for
int maxiters = -1; // maximum number of iterations allowed per linear system
int maxsubspace = 250; // maximum number of blocks the solver can use for the subspace
int recycle = 50; // maximum size of recycle space
int maxrestarts = 15; // maximum number of restarts allowed
std::string filename("sherman5.hb");
std::string ortho("IMGS");
MT tol = 1.0e-10; // relative residual tolerance
cmdp.setOption("verbose","quiet",&verbose,"Print messages and results.");
cmdp.setOption("debug","nondebug",&debug, "Print debugging information from solver.");
cmdp.setOption("left-prec","right-prec",&leftprec,"Left preconditioning or right.");
cmdp.setOption("frequency",&frequency,"Solvers frequency for printing residuals (#iters).");
cmdp.setOption("filename",&filename,"Filename for test matrix. Acceptable file extensions: *.hb,*.mtx,*.triU,*.triS");
cmdp.setOption("tol",&tol,"Relative residual tolerance used by GMRES solver.");
cmdp.setOption("num-rhs",&numrhs,"Number of right-hand sides to be solved for.");
cmdp.setOption("max-iters",&maxiters,"Maximum number of iterations per linear system (-1 = adapted to problem/block size).");
cmdp.setOption("max-subspace",&maxsubspace,"Maximum number of blocks the solver can use for the subspace.");
cmdp.setOption("recycle",&recycle,"Number of vectors in recycle space.");
cmdp.setOption("max-cycles",&maxrestarts,"Maximum number of cycles allowed for GCRO-DR solver.");
cmdp.setOption("ortho-type",&ortho,"Orthogonalization type. Must be one of DGKS, ICGS, IMGS.");
return -1;
}
if (!verbose)
frequency = -1; // reset frequency if test is not verbose
//
// *************Get the problem*********************
//
RCP<Epetra_CrsMatrix> A;
RCP<Epetra_MultiVector> B, X;
int return_val =Belos::Util::createEpetraProblem(filename,NULL,&A,NULL,NULL,&MyPID);
const Epetra_Map &Map = A->RowMap();
if(return_val != 0) return return_val;
proc_verbose = verbose && (MyPID==0); /* Only print on zero processor */
X = rcp( new Epetra_MultiVector( Map, numrhs ) );
B = rcp( new Epetra_MultiVector( Map, numrhs ) );
X->Random();
OPT::Apply( *A, *X, *B );
X->PutScalar( 0.0 );
//
// ************Construct preconditioner*************
//
if (proc_verbose) std::cout << std::endl << std::endl;
if (proc_verbose) std::cout << "Constructing ILU preconditioner" << std::endl;
int Lfill = 2;
if (proc_verbose) std::cout << "Using Lfill = " << Lfill << std::endl;
int Overlap = 2;
if (proc_verbose) std::cout << "Using Level Overlap = " << Overlap << std::endl;
double Athresh = 0.0;
if (proc_verbose) std::cout << "Using Absolute Threshold Value of " << Athresh << std::endl;
double Rthresh = 1.0;
if (proc_verbose) std::cout << "Using Relative Threshold Value of " << Rthresh << std::endl;
//
//
ilukGraph = Teuchos::rcp(new Ifpack_IlukGraph(A->Graph(), Lfill, Overlap));
int info = ilukGraph->ConstructFilledGraph();
assert( info == 0 );
ilukFactors = Teuchos::rcp(new Ifpack_CrsRiluk(*ilukGraph));
int initerr = ilukFactors->InitValues(*A);
if (initerr != 0) std::cout << "InitValues error = " << initerr;
info = ilukFactors->Factor();
assert( info == 0 );
bool transA = false;
double Cond_Est;
ilukFactors->Condest(transA, Cond_Est);
if (proc_verbose) {
std::cout << "Condition number estimate for this preconditoner = " << Cond_Est << std::endl;
std::cout << std::endl;
}
// Create the Belos preconditioned operator from the Ifpack preconditioner.
// NOTE: This is necessary because Belos expects an operator to apply the
// preconditioner with Apply() NOT ApplyInverse().
RCP<Belos::EpetraPrecOp> belosPrec = rcp( new Belos::EpetraPrecOp( ilukFactors ) );
//
// ********Other information used by block solver***********
// *****************(can be user specified)******************
//
const int NumGlobalElements = B->GlobalLength();
if (maxiters == -1)
maxiters = NumGlobalElements - 1; // maximum number of iterations to run
//
ParameterList belosList;
belosList.set( "Num Blocks", maxsubspace ); // Maximum number of blocks in Krylov factorization
belosList.set( "Maximum Iterations", maxiters ); // Maximum number of iterations allowed
belosList.set( "Maximum Restarts", maxrestarts ); // Maximum number of restarts allowed
belosList.set( "Convergence Tolerance", tol ); // Relative convergence tolerance requested
belosList.set( "Num Recycled Blocks", recycle ); // Number of vectors in recycle space
belosList.set( "Orthogonalization", ortho ); // Orthogonalization type
if (numrhs > 1) {
belosList.set( "Show Maximum Residual Norm Only", true ); // Show only the maximum residual norm
}
int verbosity = Belos::Errors + Belos::Warnings;
if (verbose) {
if (frequency > 0)
belosList.set( "Output Frequency", frequency );
}
if (debug) {
verbosity += Belos::Debug;
}
belosList.set( "Verbosity", verbosity );
//
// *******Construct a preconditioned linear problem********
//
RCP<Belos::LinearProblem<double,MV,OP> > problem
if (leftprec) {
problem->setLeftPrec( belosPrec );
}
else {
problem->setRightPrec( belosPrec );
}
bool set = problem->setProblem();
if (set == false) {
if (proc_verbose)
std::cout << std::endl << "ERROR: Belos::LinearProblem failed to set up correctly!" << std::endl;
return -1;
}
// Create an iterative solver manager.
RCP< Belos::SolverManager<double,MV,OP> > solver
= rcp( new Belos::GCRODRSolMgr<double,MV,OP>(problem, rcp(&belosList,false)));
//
// *******************************************************************
// *************Start the block Gmres iteration*************************
// *******************************************************************
//
if (proc_verbose) {
std::cout << std::endl << std::endl;
std::cout << "Dimension of matrix: " << NumGlobalElements << std::endl;
std::cout << "Number of right-hand sides: " << numrhs << std::endl;
std::cout << "Number of restarts allowed: " << maxrestarts << std::endl;
std::cout << "Max number of Gmres iterations per restart cycle: " << maxiters << std::endl;
std::cout << "Relative residual tolerance: " << tol << std::endl;
std::cout << std::endl;
}
//
// Perform solve
//
Belos::ReturnType ret = solver->solve();
//
// Compute actual residuals.
//
bool badRes = false;
std::vector<double> actual_resids( numrhs );
std::vector<double> rhs_norm( numrhs );
Epetra_MultiVector resid(Map, numrhs);
OPT::Apply( *A, *X, resid );
MVT::MvAddMv( -1.0, resid, 1.0, *B, resid );
MVT::MvNorm( resid, actual_resids );
MVT::MvNorm( *B, rhs_norm );
if (proc_verbose) {
std::cout<< "---------- Actual Residuals (normalized) ----------"<<std::endl<<std::endl;
for ( int i=0; i<numrhs; i++) {
double actRes = actual_resids[i]/rhs_norm[i];
std::cout<<"Problem "<<i<<" : \t"<< actRes <<std::endl;
if (actRes > tol) badRes = true;
}
}
if (ret!=Belos::Converged || badRes) {
success = false;
if (proc_verbose)
std::cout << std::endl << "ERROR: Belos did not converge!" << std::endl;
} else {
success = true;
if (proc_verbose)
std::cout << std::endl << "SUCCESS: Belos converged!" << std::endl;
}
}
TEUCHOS_STANDARD_CATCH_STATEMENTS(verbose, std::cerr, success);
#ifdef EPETRA_MPI
MPI_Finalize();
#endif
return success ? EXIT_SUCCESS : EXIT_FAILURE;
}

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