Belos Version of the Day
TFQMR/TFQMREpetraExFile.cpp

This is an example of how to use the Belos::TFQMRSolMgr solver manager.

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//                 Belos: Block Linear Solvers Package
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//
// 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 "BelosConfigDefs.hpp"
#include "BelosLinearProblem.hpp"
#include "BelosEpetraAdapter.hpp"
#include "BelosTFQMRSolMgr.hpp"
#include "createEpetraProblem.hpp"
#include "Ifpack_IlukGraph.h"
#include "Ifpack_CrsRiluk.h"
#include "Epetra_CrsMatrix.h"
#include "Epetra_Map.h"
#include "Teuchos_CommandLineProcessor.hpp"
#include "Teuchos_ParameterList.hpp"

int main(int argc, char *argv[]) {
  //
#ifdef EPETRA_MPI 
  MPI_Init(&argc,&argv);
  Belos::MPIFinalize mpiFinalize; // Will call finalize with *any* return
  (void)mpiFinalize;
#endif  
  //
  typedef double                            ST;
  typedef Teuchos::ScalarTraits<ST>        SCT;
  typedef SCT::magnitudeType                MT;
  typedef Epetra_MultiVector                MV;
  typedef Epetra_Operator                   OP;
  typedef Belos::MultiVecTraits<ST,MV>     MVT;
  typedef Belos::OperatorTraits<ST,MV,OP>  OPT;

  using Teuchos::ParameterList;
  using Teuchos::RCP;
  using Teuchos::rcp;

  bool verbose = false, 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

  Teuchos::CommandLineProcessor cmdp(false,true);
  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).");
  if (cmdp.parse(argc,argv) != Teuchos::CommandLineProcessor::PARSE_SUCCESSFUL) {
    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::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;
  //
  Teuchos::RCP<Ifpack_IlukGraph> ilukGraph;
  Teuchos::RCP<Ifpack_CrsRiluk> ilukFactors;
  //
  if (Lfill > -1) {
    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> 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 + 
       Belos::TimingDetails + Belos::StatusTestDetails );
    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();
  Belos::LinearProblem<double,MV,OP> problem( A, X, B );
  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 TFQMR iteration*************************
  // *******************************************************************
  //
  Teuchos::RCP< Belos::TFQMRSolMgr<double,MV,OP> > solver =
    Teuchos::rcp( new Belos::TFQMRSolMgr<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 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) {
    if (proc_verbose)
      std::cout << std::endl << "ERROR:  Belos did not converge!" << std::endl;
    return -1;
  } 
  //
  // Default return value
  //
  if (proc_verbose)
    std::cout << std::endl << "SUCCESS:  Belos converged!" << std::endl;
  return 0;

} 
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