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Ifpack_ex_Amesos.cpp
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00001 // @HEADER
00002 // ***********************************************************************
00003 // 
00004 //                IFPACK
00005 //                 Copyright (2004) Sandia Corporation
00006 // 
00007 // Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
00008 // license for use of this work by or on behalf of the U.S. Government.
00009 // 
00010 // This library is free software; you can redistribute it and/or modify
00011 // it under the terms of the GNU Lesser General Public License as
00012 // published by the Free Software Foundation; either version 2.1 of the
00013 // License, or (at your option) any later version.
00014 //  
00015 // This library is distributed in the hope that it will be useful, but
00016 // WITHOUT ANY WARRANTY; without even the implied warranty of
00017 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018 // Lesser General Public License for more details.
00019 //  
00020 // You should have received a copy of the GNU Lesser General Public
00021 // License along with this library; if not, write to the Free Software
00022 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
00023 // USA
00024 // Questions? Contact Michael A. Heroux (maherou@sandia.gov) 
00025 // 
00026 // ***********************************************************************
00027 // @HEADER
00028 
00029 #include "Ifpack_ConfigDefs.h"
00030 
00031 #ifdef HAVE_MPI
00032 #include "Epetra_MpiComm.h"
00033 #else
00034 #include "Epetra_SerialComm.h"
00035 #endif
00036 #include "Epetra_CrsMatrix.h"
00037 #include "Epetra_MultiVector.h"
00038 #include "Epetra_Map.h"
00039 #include "Epetra_BlockMap.h"
00040 #include "Epetra_LinearProblem.h"
00041 #include "Galeri_Maps.h"
00042 #include "Galeri_CrsMatrices.h"
00043 #include "Teuchos_ParameterList.hpp"
00044 #include "Teuchos_RefCountPtr.hpp"
00045 #include "AztecOO.h"
00046 #include "Ifpack.h"
00047 
00048 int main(int argc, char *argv[])
00049 {
00050 
00051   // initialize MPI and Epetra communicator
00052 #ifdef HAVE_MPI
00053   MPI_Init(&argc,&argv);
00054   Epetra_MpiComm Comm( MPI_COMM_WORLD );
00055 #else
00056   Epetra_SerialComm Comm;
00057 #endif
00058 
00059   Teuchos::ParameterList GaleriList;
00060 
00061   // The problem is defined on a 2D grid, global size is nx * nx.
00062   int nx = 30; 
00063   GaleriList.set("nx", nx);
00064   GaleriList.set("ny", nx * Comm.NumProc());
00065   GaleriList.set("mx", 1);
00066   GaleriList.set("my", Comm.NumProc());
00067   Teuchos::RefCountPtr<Epetra_Map> Map = Teuchos::rcp( Galeri::CreateMap("Cartesian2D", Comm, GaleriList) );
00068   Teuchos::RefCountPtr<Epetra_RowMatrix> A = Teuchos::rcp( Galeri::CreateCrsMatrix("Laplace2D", &*Map, GaleriList) );
00069 
00070   // =============================================================== //
00071   // 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 //
00072   // =============================================================== //
00073 
00074   Teuchos::ParameterList List;
00075 
00076   // allocates an IFPACK factory. No data is associated 
00077   // to this object (only method Create()).
00078   Ifpack Factory;
00079 
00080   // create the preconditioner. For valid PrecType values,
00081   // please check the documentation
00082   string PrecType = "Amesos";
00083   int OverlapLevel = 2; // must be >= 0. If Comm.NumProc() == 1,
00084                         // it is ignored.
00085 
00086   Teuchos::RefCountPtr<Ifpack_Preconditioner> Prec = Teuchos::rcp( Factory.Create(PrecType, &*A, OverlapLevel) );
00087   assert(Prec != Teuchos::null);
00088 
00089   // specify the Amesos solver to be used. 
00090   // If the selected solver is not available,
00091   // IFPACK will try to use Amesos' KLU (which is usually always
00092   // compiled). Amesos' serial solvers are:
00093   // "Amesos_Klu", "Amesos_Umfpack", "Amesos_Superlu"
00094   List.set("amesos: solver type", "Amesos_Klu");
00095 
00096   // sets the parameters
00097   IFPACK_CHK_ERR(Prec->SetParameters(List));
00098 
00099   // initialize the preconditioner. At this point the matrix must
00100   // have been FillComplete()'d, but actual values are ignored.
00101   // At this call, Amesos will perform the symbolic factorization.
00102   IFPACK_CHK_ERR(Prec->Initialize());
00103 
00104   // Builds the preconditioners, by looking for the values of 
00105   // the matrix. At this call, Amesos will perform the
00106   // numeric factorization.
00107   IFPACK_CHK_ERR(Prec->Compute());
00108 
00109   // =================================================== //
00110   // E N D   O F   I F P A C K   C O N S T R U C T I O N //
00111   // =================================================== //
00112 
00113   // At this point, we need some additional objects
00114   // to define and solve the linear system.
00115 
00116   // defines LHS and RHS
00117   Epetra_Vector LHS(A->OperatorDomainMap());
00118   Epetra_Vector RHS(A->OperatorDomainMap());
00119 
00120   // solution is constant
00121   LHS.PutScalar(1.0);
00122   // now build corresponding RHS
00123   A->Apply(LHS,RHS);
00124 
00125   // now randomize the solution
00126   RHS.Random();
00127 
00128   // need an Epetra_LinearProblem to define AztecOO solver
00129   Epetra_LinearProblem Problem(&*A,&LHS,&RHS);
00130 
00131   // now we can allocate the AztecOO solver
00132   AztecOO Solver(Problem);
00133 
00134   // specify solver
00135   Solver.SetAztecOption(AZ_solver,AZ_gmres);
00136   Solver.SetAztecOption(AZ_output,32);
00137 
00138   // HERE WE SET THE IFPACK PRECONDITIONER
00139   Solver.SetPrecOperator(&*Prec);
00140 
00141   // .. and here we solve
00142   // NOTE: with one process, the solver must converge in
00143   // one iteration.
00144   Solver.Iterate(1550,1e-8);
00145 
00146 #ifdef HAVE_MPI
00147   MPI_Finalize() ; 
00148 #endif
00149 
00150     return(EXIT_SUCCESS);
00151 }
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