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ml_analyze.cpp
/* ******************************************************************** */
/* See the file COPYRIGHT for a complete copyright notice, contact */
/* person and disclaimer. */
/* ******************************************************************** */
//@HEADER
// Goal of this example is to show the (limited) ML analysis capabilities.
//
// \author Marzio Sala, SNL 9214
//
// \date Last modified on 14-Jun-05
#include "ml_include.h"
// The C++ interface of ML (more precisely,
// ML_Epetra::MultiLevelPreconditioner), requires Trilinos to be
// configured with --enable-epetra --enable-teuchos. This example
// required --enable-galeri (for the definition of the linear systems)
#if defined(HAVE_ML_EPETRA) && defined(HAVE_ML_AZTECOO) && defined(HAVE_ML_TEUCHOS) && defined(HAVE_ML_GALERI)
#ifdef HAVE_MPI
#include "mpi.h"
#include "Epetra_MpiComm.h"
#else
#include "Epetra_SerialComm.h"
#endif
#include "Epetra_Map.h"
#include "Epetra_Vector.h"
#include "Epetra_CrsMatrix.h"
#include "Epetra_LinearProblem.h"
#include "Galeri_Maps.h"
#include "Galeri_CrsMatrices.h"
#include "Galeri_Utils.h"
using namespace Teuchos;
using namespace Galeri;
// ============== //
// example driver //
// ============== //
int main(int argc, char *argv[])
{
#ifdef HAVE_MPI
MPI_Init(&argc,&argv);
Epetra_MpiComm Comm(MPI_COMM_WORLD);
#else
#endif
// Creates the linear problem using the Galeri package.
// Several matrix examples are supported; please refer to the
// Galeri documentation for more details.
// Most of the examples using the ML_Epetra::MultiLevelPreconditioner
// class are based on Epetra_CrsMatrix. Example
// `ml_EpetraVbr.cpp' shows how to define a Epetra_VbrMatrix.
// `Laplace2D' is a symmetric matrix; an example of non-symmetric
// matrices is `Recirc2D' (advection-diffusion in a box, with
// recirculating flow). The grid has nx x ny nodes, divided into
// mx x my subdomains, each assigned to a different processor.
int nx = 28;
int ny = 28 * Comm.NumProc();
ParameterList GaleriList;
GaleriList.set("nx", nx);
GaleriList.set("ny", ny);
GaleriList.set("mx", 1);
GaleriList.set("my", Comm.NumProc());
Epetra_Map* Map = CreateMap("Cartesian2D", Comm, GaleriList);
Epetra_CrsMatrix* A = CreateCrsMatrix("Laplace2D", Map, GaleriList);
// create a parameter list for ML options
ParameterList MLList;
// set defaults for smoothed aggregation
ML_Epetra::SetDefaults("SA",MLList);
// use Uncoupled scheme to create the aggregate
MLList.set("aggregation: type", "Uncoupled");
// fix the smoother
MLList.set("smoother: type","symmetric Gauss-Seidel");
// create the preconditioning object.
// Note that users need to set "viz: enable" == true in order to
// visualize!
new ML_Epetra::MultiLevelPreconditioner(*A, MLList, true);
// for 2D Cartesian grid, you can print the stencil of your operator
// using this simple function.
MLPrec->PrintStencil2D(nx, ny);
// ================================================= //
// A N A L Y S I S O F T H E H I E R A R C H Y //
// ================================================= //
// Method AnalyzeHierarchy() can be used to validate an
// already built hierarchy.
// - `true' means perform a "cheap" analysis of each level's matrix
// - Then, each level's smoothers and the complete cycle are
// applied to solve the problem
// A e = 0
// with a random initial solution, to get a sense of the effectiveness
// of the smoothers and the cycle itself. The parameters are:
// * NumPreCycles and NumPostCycles specify the number of post
// and pre smoother applications;
// * NumMLCycles specifies the number of applications of the
// complete cycle.
int NumPreCycles = 5;
int NumPostCycles = 1;
int NumMLCycles = 10;
MLPrec->AnalyzeHierarchy(true, NumPreCycles, NumPostCycles, NumMLCycles);
// ================================================= //
// A N A L Y S I S O F T H E S M O O T H E R S //
// ================================================= //
// Method TestSmoothers() can be used to analyze different smoothers
// on a given problem. The cycle is built following the parameters
// specified in MLTestList.
// Please refer to the user's guide for more details about the following
// parameters. Not all smoothers are supported by this testing.
ML_Epetra::SetDefaults("SA",MLTestList);
MLPrec->TestSmoothers(MLTestList);
// =============== //
// end of analysis //
// =============== //
delete MLPrec;
delete A;
delete Map;
#ifdef HAVE_MPI
MPI_Finalize() ;
#endif
return(EXIT_SUCCESS);
}
#else
#include <stdlib.h>
#include <stdio.h>
#ifdef HAVE_MPI
#include "mpi.h"
#endif
int main(int argc, char *argv[])
{
#ifdef HAVE_MPI
MPI_Init(&argc,&argv);
#endif
puts("Please configure ML with:");
puts("--enable-epetra");
puts("--enable-teuchos");
puts("--enable-galeri");
puts("--enable-aztecoo");
#ifdef HAVE_MPI
MPI_Finalize();
#endif
return 0;
}
#endif