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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.
//
// As currently set up, this driver tests the case when the number of right-hand
// sides (numrhs = 15) is greater than the blocksize (block = 10) used by
// the solver. Here, 2 passes through the solver are required to solve
// for all right-hand sides. This information can be edited (see below - other
// information used by block solver - can be user specified) to solve for
// other sizes of systems. For example, one could set numrhs = 1 and block = 1,
// to solve a single right-hand side system in the traditional way, or, set
// numrhs = 1 and block > 1 to solve a single rhs-system with a block implementation.
//
//
#include "BelosConfigDefs.hpp"
#include "BelosLinearProblem.hpp"
#include "BelosEpetraAdapter.hpp"
#include "BelosPseudoBlockStochasticCGSolMgr.hpp"
#include "createEpetraProblem.hpp"
#include "Trilinos_Util.h"
#include "Epetra_CrsMatrix.h"
#include "Epetra_Map.h"
#include "Teuchos_CommandLineProcessor.hpp"
#include "Teuchos_ParameterList.hpp"
#include "Teuchos_StandardCatchMacros.hpp"

#include "Ifpack.h"
//
int main(int argc, char *argv[]) {
  //
  Teuchos::GlobalMPISession session(&argc, &argv, NULL);
  //
  using Teuchos::ParameterList;
  using Teuchos::RCP;
  using Teuchos::rcp;

  bool success = false;
  bool verbose = false;
  try {
    //
    // Get test parameters from command-line processor
    //
    bool proc_verbose = false;
    bool leftprec = true;      // left preconditioning or right.
    int frequency = -1; // how often residuals are printed by solver
    int numrhs = 15;  // total number of right-hand sides to solve for
    int blocksize = 10;  // blocksize used by solver
    int maxiters = -1; // maximum number of iterations for the solver to use
    std::string filename("bcsstk14.hb");
    double 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 CG solver.");
    cmdp.setOption("num-rhs",&numrhs,"Number of right-hand sides to be solved for.");
    cmdp.setOption("block-size",&blocksize,"Block size to be used by CG solver.");
    cmdp.setOption("max-iters",&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 verbosity is off
    //
    // Get the problem
    //
    int MyPID;
    RCP<Epetra_CrsMatrix> A;
    RCP<Epetra_MultiVector> X, B;
    int return_val =Belos::createEpetraProblem(filename,NULL,&A,&B,&X,&MyPID);
    if(return_val != 0) return return_val;
    proc_verbose = ( verbose && (MyPID==0) );
    //
    // Solve using Belos
    //
    typedef double                           ST;
    typedef Epetra_Operator                  OP;
    typedef Epetra_MultiVector               MV;
    typedef Belos::OperatorTraits<ST,MV,OP> OPT;
    typedef Belos::MultiVecTraits<ST,MV>    MVT;
    //
    // *****Construct initial guess and random right-hand-sides *****
    //
    if (numrhs != 1) {
      X = rcp( new Epetra_MultiVector( A->Map(), numrhs ) );
      MVT::MvRandom( *X );
      B = rcp( new Epetra_MultiVector( A->Map(), numrhs ) );
      OPT::Apply( *A, *X, *B );
      MVT::MvInit( *X, 0.0 );
    }
    //
    // ************Construct preconditioner*************
    //
    ParameterList ifpackList;

    // allocates an IFPACK factory. No data is associated
    // to this object (only method Create()).
    Ifpack Factory;

    // create the preconditioner. For valid PrecType values,
    // please check the documentation
    std::string PrecType = "ICT"; // incomplete Cholesky
    int OverlapLevel = 0; // must be >= 0. If Comm.NumProc() == 1,
    // it is ignored.

    RCP<Ifpack_Preconditioner> Prec = Teuchos::rcp( Factory.Create(PrecType, &*A, OverlapLevel) );
    assert(Prec != Teuchos::null);

    // specify parameters for ICT
    ifpackList.set("fact: drop tolerance", 1e-9);
    ifpackList.set("fact: ict level-of-fill", 1.0);
    // the combine mode is on the following:
    // "Add", "Zero", "Insert", "InsertAdd", "Average", "AbsMax"
    // Their meaning is as defined in file Epetra_CombineMode.h
    ifpackList.set("schwarz: combine mode", "Add");
    // sets the parameters
    IFPACK_CHK_ERR(Prec->SetParameters(ifpackList));

    // initialize the preconditioner. At this point the matrix must
    // have been FillComplete()'d, but actual values are ignored.
    IFPACK_CHK_ERR(Prec->Initialize());

    // Builds the preconditioners, by looking for the values of
    // the matrix.
    IFPACK_CHK_ERR(Prec->Compute());

    // 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( Prec ) );

    //
    // *****Create parameter list for the block CG solver manager*****
    //
    const int NumGlobalElements = B->GlobalLength();
    if (maxiters == -1)
      maxiters = NumGlobalElements/blocksize - 1; // maximum number of iterations to run
    //
    ParameterList belosList;
    belosList.set( "Block Size", blocksize );              // Blocksize to be used by iterative solver
    belosList.set( "Maximum Iterations", maxiters );       // Maximum number of iterations allowed
    belosList.set( "Convergence Tolerance", tol );         // Relative convergence tolerance requested
    if (verbose) {
      belosList.set( "Verbosity", Belos::Errors + Belos::Warnings +
          Belos::TimingDetails + Belos::FinalSummary + Belos::StatusTestDetails );
      if (frequency > 0)
        belosList.set( "Output Frequency", frequency );
    }
    else
      belosList.set( "Verbosity", Belos::Errors + Belos::Warnings );
    //
    // *******Construct a preconditioned linear problem********
    //
    RCP<Belos::LinearProblem<double,MV,OP> > problem
      = rcp( new Belos::LinearProblem<double,MV,OP>( A, X, B ) );
    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::PseudoBlockStochasticCGSolMgr<double,MV,OP>(problem, rcp(&belosList,false)) );

    //
    // *******************************************************************
    // *************Start the block CG 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 << "Block size used by solver: " << blocksize << std::endl;
      std::cout << "Max number of CG 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 resid(A->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;
      }
    }

    success = ret==Belos::Converged && !badRes;

    if (success) {
      if (proc_verbose)
        std::cout << std::endl << "End Result: TEST PASSED" << std::endl;
    } else {
      if (proc_verbose)
        std::cout << std::endl << "End Result: TEST FAILED" << std::endl;
    }
  }
  TEUCHOS_STANDARD_CATCH_STATEMENTS(verbose, std::cerr, success);

  return ( success ? EXIT_SUCCESS : EXIT_FAILURE );
} // end test_bl_pcg_hb.cpp

