Ex_Factory

// @HEADER
// ***********************************************************************
// 
//                IFPACK
//                 Copyright (2004) Sandia Corporation
// 
// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
// license for use of this work by or on behalf of the U.S. Government.
// 
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//  
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//  
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA
// Questions? Contact Michael A. Heroux (maherou@sandia.gov) 
// 
// ***********************************************************************
// @HEADER

#include "Ifpack_ConfigDefs.h"
#if defined(HAVE_IFPACK_AZTECOO)  && defined(HAVE_IFPACK_TEUCHOS) && defined(HAVE_IFPACK_TRIUTILS) 
#ifdef HAVE_MPI
#include "Epetra_MpiComm.h"
#else
#include "Epetra_SerialComm.h"
#endif
#include "Epetra_CrsMatrix.h"
#include "Epetra_MultiVector.h"
#include "Epetra_LinearProblem.h"
#include "Trilinos_Util_CrsMatrixGallery.h"
#include "Teuchos_ParameterList.hpp"
#include "AztecOO.h"
#include "Ifpack.h"
#include "Ifpack_AdditiveSchwarz.h"

using namespace Trilinos_Util;

int main(int argc, char *argv[])
{

#ifdef HAVE_MPI
  MPI_Init(&argc,&argv);
  Epetra_MpiComm Comm( MPI_COMM_WORLD );
#else
  Epetra_SerialComm Comm;
#endif

  // size of the global matrix (must be a square number)
  const int NumPoints = 10000;

  // build the matrix corresponding to a 2D Laplacian on a
  // structured grid.
  CrsMatrixGallery Gallery("laplace_2d", Comm);
  Gallery.Set("problem_size", NumPoints);
  // for simplicity, linear map.
  Gallery.Set("map_type", "linear");

  // get the pointer to the linear system matrix
  Epetra_RowMatrix* A = Gallery.GetMatrix();

  // =============================================================== //
  // B E G I N N I N G   O F   I F P A C K   C O N S T R U C T I O N //
  // =============================================================== //

  Teuchos::ParameterList List;

  // 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
  string PrecType = "ILU"; // incomplete LU
  int OverlapLevel = 1; // must be >= 0. If Comm.NumProc() == 1,
                        // it is ignored.

  Ifpack_Preconditioner* Prec = Factory.Create(PrecType, A, OverlapLevel);
  assert(Prec != 0);

  // specify parameters for ILU
  List.set("fact: drop tolerance", 1e-9);
  List.set("fact: level-of-fill", 1);

  // sets the parameters
  IFPACK_CHK_ERR(Prec->SetParameters(List));

  // 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());

  // =================================================== //
  // E N D   O F   I F P A C K   C O N S T R U C T I O N //
  // =================================================== //

  // At this point, we need some additional objects
  // to define and solve the linear system.

  // defines LHS and RHS
  Epetra_Vector LHS(A->OperatorDomainMap());
  Epetra_Vector RHS(A->OperatorDomainMap());

  // solution is constant
  LHS.PutScalar(1.0);
  // now build corresponding RHS
  A->Apply(LHS,RHS);

  // now randomize the solution
  RHS.Random();

  // need an Epetra_LinearProblem to define AztecOO solver
  Epetra_LinearProblem Problem(A,&LHS,&RHS);

  // now we can allocate the AztecOO solver
  AztecOO Solver(Problem);

  // specify solver
  Solver.SetAztecOption(AZ_solver,AZ_gmres);
  Solver.SetAztecOption(AZ_output,32);

  // HERE WE SET THE IFPACK PRECONDITIONER
  Solver.SetPrecOperator(Prec);

  // .. and here we solve
  Solver.Iterate(1550,1e-8);

  cout << *Prec;

  // delete the preconditioner
  delete Prec;
  
#ifdef HAVE_MPI
  MPI_Finalize() ; 
#endif

    return(EXIT_SUCCESS);
}

#else

#ifdef HAVE_MPI
#include "Epetra_MpiComm.h"
#else
#include "Epetra_SerialComm.h"
#endif

int main(int argc, char *argv[])
{

#ifdef HAVE_MPI
  MPI_Init(&argc,&argv);
  Epetra_MpiComm Comm( MPI_COMM_WORLD );
#else
  Epetra_SerialComm Comm;
#endif

  puts("please configure IFPACK with --enable-aztecoo --enable-teuchos");
  puts("--enable-triutils to run this test");

#ifdef HAVE_MPI
  MPI_Finalize() ;
#endif
  return(EXIT_SUCCESS);
}

#endif

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