MultiLevel.cpp

/* ******************************************************************** */
/* See the file COPYRIGHT for a complete copyright notice, contact      */
/* person and disclaimer.                                               */        
/* ******************************************************************** */

#include "ml_config.h"
#include "ml_common.h"

#if defined(HAVE_ML_MLAPI) && defined(HAVE_ML_GALERI)
#include "MLAPI_Space.h"
#include "MLAPI_Operator.h"
#include "MLAPI_MultiVector.h"
#include "MLAPI_Gallery.h"
#include "MLAPI_Expressions.h"
#include "MLAPI_MultiLevelSA.h"
#include "MLAPI_Krylov.h"

using namespace Teuchos;
using namespace MLAPI;

// ============== //
// example driver //
// ============== //

int main(int argc, char *argv[])
{
  
#ifdef HAVE_MPI
  MPI_Init(&argc,&argv);
#endif

  try {

    // Initialize the workspace and set the output level
    Init();

    int NumGlobalElements = 100;

    // define the space for fine level vectors and operators.
    Space FineSpace(NumGlobalElements);

    // define the linear system matrix, solution and RHS
    Operator FineMatrix = Gallery("Tridiag", FineSpace);
    MultiVector LHS(FineSpace);
    MultiVector RHS(FineSpace);

    LHS = 0.0;
    RHS = 1.0;

    // set parameters for aggregation and smoothers
    // NOTE: only a limited subset of the parameters accepted by
    // class ML_Epetra::MultiLevelPreconditioner is supported
    // by MLAPI::MultiLevelSA
    
    Teuchos::ParameterList MLList;
    MLList.set("max levels",2);
    MLList.set("increasing or decreasing","increasing");
    MLList.set("aggregation: type", "Uncoupled");
    MLList.set("aggregation: damping factor", 0.0);
    MLList.set("smoother: type","symmetric Gauss-Seidel");
    MLList.set("smoother: sweeps",1);
    MLList.set("smoother: damping factor",1.0);
    MLList.set("coarse: max size",3);
    MLList.set("smoother: pre or post", "both");
    MLList.set("coarse: type","Amesos-KLU");

    MultiLevelSA Prec(FineMatrix, MLList);

    // solve with GMRES (through AztecOO)
    MLList.set("krylov: solver", "gmres");
    MLList.set("krylov: max iterations", 1550);
    MLList.set("krylov: tolerance", 1e-9);
    MLList.set("krylov: output level", 10);
    Krylov(FineMatrix, LHS, RHS, Prec, MLList);

    cout << Prec;
  }
  catch (const int e) {
    cerr << "Caught exception, code = " << e << endl;
  }
  catch (...) {
    cerr << "Caught exception..." << endl;
  }

  Finalize();

#ifdef HAVE_MPI
  MPI_Finalize();
#endif

  return(0);
}

#else

#include "ml_include.h"

int main(int argc, char *argv[])
{
#ifdef HAVE_MPI
  MPI_Init(&argc,&argv);
#endif

  puts("This MLAPI example requires the following configuration options:");
  puts("\t--enable-epetra");
  puts("\t--enable-teuchos");
  puts("\t--enable-ifpack");
  puts("\t--enable-amesos");
  puts("\t--enable-galeri");
  puts("Please check your configure line.");

#ifdef HAVE_MPI
  MPI_Finalize();
#endif

  return(0);
}

#endif // #if defined(HAVE_ML_MLAPI)