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epetra/example/TFQMR/PseudoBlockTFQMREpetraExFile.cpp

This is an example of how to use the Belos::PseudoBlockTFQMRSolMgr solver manager using Epetra.

// @HEADER
// *****************************************************************************
// Belos: Block Linear Solvers Package
//
// Copyright 2004-2016 NTESS and the Belos contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER
//
// This driver reads a problem from a Harwell-Boeing (HB) file.
// Multiple right-hand-sides are created randomly.
// The initial guesses are all set to zero.
//
#include "BelosEpetraAdapter.hpp"
#include "BelosEpetraUtils.h"
#include "Ifpack_IlukGraph.h"
#include "Ifpack_CrsRiluk.h"
#include "Epetra_CrsMatrix.h"
#include "Epetra_Map.h"
#include "Teuchos_StandardCatchMacros.hpp"
#include "Teuchos_Assert.hpp"
int main(int argc, char *argv[]) {
//
Teuchos::GlobalMPISession session(&argc, &argv, NULL);
//
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 leftprec = true; // use left preconditioning to solve these linear systems
int frequency = -1; // how often residuals are printed by solver
int numrhs = 1;
int maxiters = -1; // maximum iterations allowed
std::string filename("orsirr1.hb");
MT tol = 1.0e-5; // relative residual tolerance
cmdp.setOption("verbose","quiet",&verbose,"Print messages and results.");
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 Harwell-Boeing test matrix.");
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("maxiters",&maxiters,"Maximum number of iterations per linear system (-1 = adapted to problem/block size).");
return -1;
}
if (!verbose)
frequency = -1; // reset frequency if test is not verbose
//
// Get the problem
//
int MyPID;
RCP<Epetra_CrsMatrix> A;
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 */
//
// *****Construct the Preconditioner*****
//
if (proc_verbose) std::cout << std::endl << std::endl;
if (proc_verbose) std::cout << "Constructing ILU preconditioner" << std::endl;
int Lfill = 2;
// if (argc > 2) Lfill = atoi(argv[2]);
if (proc_verbose) std::cout << "Using Lfill = " << Lfill << std::endl;
int Overlap = 2;
// if (argc > 3) Overlap = atoi(argv[3]);
if (proc_verbose) std::cout << "Using Level Overlap = " << Overlap << std::endl;
double Athresh = 0.0;
// if (argc > 4) Athresh = atof(argv[4]);
if (proc_verbose) std::cout << "Using Absolute Threshold Value of " << Athresh << std::endl;
double Rthresh = 1.0;
// if (argc >5) Rthresh = atof(argv[5]);
if (proc_verbose) std::cout << "Using Relative Threshold Value of " << Rthresh << std::endl;
//
//
if (Lfill > -1) {
ilukGraph = Teuchos::rcp(new Ifpack_IlukGraph(A->Graph(), Lfill, Overlap));
int info = ilukGraph->ConstructFilledGraph();
TEUCHOS_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();
TEUCHOS_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> Prec = rcp( new Belos::EpetraPrecOp( ilukFactors ) );
//
// ********Other information used by block solver***********
// *****************(can be user specified)******************
//
const int NumGlobalElements = Map.NumGlobalElements();
if (maxiters == -1)
maxiters = NumGlobalElements - 1; // maximum number of iterations to run
//
ParameterList belosList;
belosList.set( "Maximum Iterations", maxiters ); // Maximum number of iterations allowed
belosList.set( "Convergence Tolerance", tol ); // Relative convergence tolerance requested
if (leftprec)
belosList.set( "Explicit Residual Test", true ); // Need to check for the explicit residual before returning
if (verbose) {
belosList.set( "Verbosity", Belos::Errors + Belos::Warnings +
if (frequency > 0)
belosList.set( "Output Frequency", frequency );
}
else
belosList.set( "Verbosity", Belos::Errors + Belos::Warnings );
//
// *****Construct solution std::vector and random right-hand-sides *****
//
RCP<Epetra_MultiVector> X = rcp( new Epetra_MultiVector(Map, numrhs) );
X->PutScalar( 0.0 );
RCP<Epetra_MultiVector> B = rcp( new Epetra_MultiVector(Map, numrhs) );
B->Random();
if (leftprec)
problem.setLeftPrec( Prec );
else
problem.setRightPrec( Prec );
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;
}
//
// *******************************************************************
// ************Start the Pseudo Block TFQMR iteration*****************
// *******************************************************************
//
Teuchos::rcp( new Belos::PseudoBlockTFQMRSolMgr<double,MV,OP>( rcp(&problem,false), rcp(&belosList,false) ) );
//
// **********Print out information about problem*******************
//
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 << "Max number of Pseudo Block TFQMR iterations: " << 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 R(Map, numrhs);
OPT::Apply( *A, *X, R );
MVT::MvAddMv( -1.0, R, 1.0, *B, R );
MVT::MvNorm( R, 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);
return success ? EXIT_SUCCESS : EXIT_FAILURE;
}

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