Ifpack_ex_Reordering.cpp

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//       Ifpack: Object-Oriented Algebraic Preconditioner Package
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#include "Ifpack_ConfigDefs.h"
#ifdef HAVE_MPI
#include "Epetra_MpiComm.h"
#else
#include "Epetra_SerialComm.h"
#endif
#include "Epetra_Map.h"
#include "Epetra_CrsMatrix.h"
#include "Ifpack_Reordering.h"
#include "Ifpack_RCMReordering.h"
#include "Ifpack_ReorderFilter.h"
#include "Ifpack_Utils.h"
#include "Teuchos_RefCountPtr.hpp"

//==============================================================================
int main(int argc, char *argv[])
{
  using std::cout;
  using std::endl;

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

  // only one process
  if (Comm.NumProc() != 1) {
#ifdef HAVE_MPI
    MPI_Finalize();
#endif
    if (Comm.MyPID() == 0)
      cout << "Please run this test with one process only" << endl;
    // return success not to break the tests
    exit(EXIT_SUCCESS);
  }

  // ======================================================== //
  // now create the famous "upper arrow" matrix, which        //
  // should be reordered as a "lower arrow". Sparsity pattern //
  // will be printed on screen.                               //
  // ======================================================== //

  int NumPoints = 16;

#if !defined(EPETRA_NO_32BIT_GLOBAL_INDICES) || !defined(EPETRA_NO_64BIT_GLOBAL_INDICES)
  Epetra_Map Map(-1,NumPoints,0,Comm);
#else
  Epetra_Map Map;
#endif

  std::vector<int> Indices(NumPoints);
  std::vector<double> Values(NumPoints);

  Teuchos::RefCountPtr<Epetra_CrsMatrix> A = Teuchos::rcp( new Epetra_CrsMatrix(Copy,Map,0) );
  for (int i = 0 ; i < NumPoints ; ++i) {

    int NumEntries;
    if (i == 0) {
      NumEntries = NumPoints;
      for (int j = 0 ; j < NumPoints ; ++j) {
        Indices[j] = j;
        Values[j] = 1.0;
      }
    }
    else {
      NumEntries = 2;
      Indices[0] = 0;
      Indices[1] = i;
      Values[0] = 1.0;
      Values[1] = 1.0;
    }

#if !defined(EPETRA_NO_32BIT_GLOBAL_INDICES) || !defined(EPETRA_NO_64BIT_GLOBAL_INDICES)
    A->InsertGlobalValues(i, NumEntries, &Values[0], &Indices[0]);
#endif
  }

  A->FillComplete();

  // print the sparsity to file, postscript format

  // create the reordering...
  Teuchos::RefCountPtr<Ifpack_RCMReordering> Reorder = Teuchos::rcp( new Ifpack_RCMReordering() );
  // and compute is on A
  IFPACK_CHK_ERR(Reorder->Compute(*A));

  // cout information
  cout << *Reorder;

  // create a reordered matrix
  Ifpack_ReorderFilter ReordA(A, Reorder);

  // print the sparsity to file, postscript format

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

}