Ifpack Package Browser (Single Doxygen Collection) Development
Loading...
Searching...
No Matches
Ifpack_ex_ICT_LL.cpp
Go to the documentation of this file.
1// @HEADER
2// ***********************************************************************
3//
4// IFPACK
5// Copyright (2004) Sandia Corporation
6//
7// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
8// license for use of this work by or on behalf of the U.S. Government.
9//
10// This library is free software; you can redistribute it and/or modify
11// it under the terms of the GNU Lesser General Public License as
12// published by the Free Software Foundation; either version 2.1 of the
13// License, or (at your option) any later version.
14//
15// This library is distributed in the hope that it will be useful, but
16// WITHOUT ANY WARRANTY; without even the implied warranty of
17// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18// Lesser General Public License for more details.
19//
20// You should have received a copy of the GNU Lesser General Public
21// License along with this library; if not, write to the Free Software
22// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
23// USA
24// Questions? Contact Michael A. Heroux (maherou@sandia.gov)
25//
26// ***********************************************************************
27// @HEADER
28
29#include "Ifpack_ConfigDefs.h"
30
31#ifdef HAVE_MPI
32#include "Epetra_MpiComm.h"
33#else
34#include "Epetra_SerialComm.h"
35#endif
36#include "Epetra_CrsMatrix.h"
37#include "Epetra_MultiVector.h"
38#include "Epetra_LinearProblem.h"
39#include "Epetra_Time.h"
40#include "Galeri_Maps.h"
41#include "Galeri_CrsMatrices.h"
42#include "Teuchos_ParameterList.hpp"
43#include "Teuchos_RefCountPtr.hpp"
44#include "AztecOO.h"
46#include "Ifpack_ICT.h"
47
48int main(int argc, char *argv[])
49{
50
51 // initialize MPI and Epetra communicator
52#ifdef HAVE_MPI
53 MPI_Init(&argc,&argv);
54 Epetra_MpiComm Comm( MPI_COMM_WORLD );
55#else
57#endif
58
59 Teuchos::ParameterList GaleriList;
60
61 // The problem is defined on a 2D grid, global size is nx * nx.
62 int nx = 30;
63 GaleriList.set("nx", nx);
64 GaleriList.set("ny", nx * Comm.NumProc());
65 GaleriList.set("mx", 1);
66 GaleriList.set("my", Comm.NumProc());
67 Teuchos::RefCountPtr<Epetra_Map> Map = Teuchos::rcp( Galeri::CreateMap64("Cartesian2D", Comm, GaleriList) );
68 Teuchos::RefCountPtr<Epetra_RowMatrix> A = Teuchos::rcp( Galeri::CreateCrsMatrix("Laplace2D", &*Map, GaleriList) );
69
70 // =============================================================== //
71 // 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 //
72 // =============================================================== //
73
74 Teuchos::ParameterList List;
75
76 // builds an Ifpack_AdditiveSchwarz. This is templated with
77 // the local solvers, in this case Ifpack_ICT. Note that any
78 // other Ifpack_Preconditioner-derived class can be used
79 // instead of Ifpack_ICT.
80
81 // In this example the overlap is zero. Use
82 // Prec(A,OverlapLevel) for the general case.
84
85 // `1.0' means that the factorization should approximatively
86 // keep the same number of nonzeros per row of the original matrix.
87 List.set("fact: ict level-of-fill", 1.0);
88 // no modifications on the diagonal
89 List.set("fact: absolute threshold", 0.0);
90 List.set("fact: relative threshold", 1.0);
91 List.set("fact: relaxation value", 0.0);
92 // matrix `laplace_2d_bc' is not symmetric because of the way
93 // boundary conditions are imposed. We can filter the singletons,
94 // (that is, Dirichlet nodes) and end up with a symmetric
95 // matrix (as ICT requires).
96 List.set("schwarz: filter singletons", true);
97
98 // sets the parameters
99 IFPACK_CHK_ERR(Prec.SetParameters(List));
100
101 // initialize the preconditioner. At this point the matrix must
102 // have been FillComplete()'d, but actual values are ignored.
104
105 // Builds the preconditioners, by looking for the values of
106 // the matrix.
107 IFPACK_CHK_ERR(Prec.Compute());
108
109 // =================================================== //
110 // E N D O F I F P A C K C O N S T R U C T I O N //
111 // =================================================== //
112
113 // At this point, we need some additional objects
114 // to define and solve the linear system.
115
116 // defines LHS and RHS
117 Epetra_Vector LHS(A->OperatorDomainMap());
118 Epetra_Vector RHS(A->OperatorDomainMap());
119
120 LHS.PutScalar(0.0);
121 RHS.Random();
122
123 // need an Epetra_LinearProblem to define AztecOO solver
124 Epetra_LinearProblem Problem(&*A,&LHS,&RHS);
125
126 // now we can allocate the AztecOO solver
127 AztecOO Solver(Problem);
128
129 // specify solver
130 Solver.SetAztecOption(AZ_solver,AZ_cg_condnum);
131 Solver.SetAztecOption(AZ_output,32);
132
133 // HERE WE SET THE IFPACK PRECONDITIONER
134 Solver.SetPrecOperator(&Prec);
135
136 // .. and here we solve
137 // NOTE: with one process, the solver must converge in
138 // one iteration.
139 Solver.Iterate(1550,1e-5);
140
141 // Prints out some information about the preconditioner
142 std::cout << Prec;
143
144#ifdef HAVE_MPI
145 MPI_Finalize();
146#endif
147
148 return (EXIT_SUCCESS);
149}
Solver
#define IFPACK_CHK_ERR(ifpack_err)
int main(int argc, char *argv[])
#define RHS(a)
Definition: MatGenFD.c:60
int NumProc() const
int PutScalar(double ScalarConstant)
Ifpack_AdditiveSchwarz: a class to define Additive Schwarz preconditioners of Epetra_RowMatrix's.
virtual int SetParameters(Teuchos::ParameterList &List)
Sets the parameters.
virtual int Compute()
Computes the preconditioner.
virtual int Initialize()
Initialized the preconditioner.