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Ifpack_ex_Factory_LL.cpp
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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 "Galeri_Maps.h"
40 #include "Galeri_CrsMatrices.h"
41 #include "Teuchos_ParameterList.hpp"
42 #include "Teuchos_RefCountPtr.hpp"
43 #include "AztecOO.h"
44 #include "Ifpack.h"
45 #include "Ifpack_AdditiveSchwarz.h"
46 
47 int main(int argc, char *argv[])
48 {
49 
50 #ifdef HAVE_MPI
51  MPI_Init(&argc,&argv);
52  Epetra_MpiComm Comm( MPI_COMM_WORLD );
53 #else
54  Epetra_SerialComm Comm;
55 #endif
56 
57  Teuchos::ParameterList GaleriList;
58 
59  // The problem is defined on a 2D grid, global size is nx * nx.
60  int nx = 30;
61  GaleriList.set("n", nx * nx);
62  GaleriList.set("nx", nx);
63  GaleriList.set("ny", nx);
64  Teuchos::RefCountPtr<Epetra_Map> Map = Teuchos::rcp( Galeri::CreateMap64("Linear", Comm, GaleriList) );
65  Teuchos::RefCountPtr<Epetra_RowMatrix> A = Teuchos::rcp( Galeri::CreateCrsMatrix("Laplace2D", &*Map, GaleriList) );
66 
67  // =============================================================== //
68  // 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 //
69  // =============================================================== //
70 
72 
73  // allocates an IFPACK factory. No data is associated
74  // to this object (only method Create()).
75  Ifpack Factory;
76 
77  // create the preconditioner. For valid PrecType values,
78  // please check the documentation
79  std::string PrecType = "ILU"; // incomplete LU
80  int OverlapLevel = 1; // must be >= 0. If Comm.NumProc() == 1,
81  // it is ignored.
82 
83  Teuchos::RefCountPtr<Ifpack_Preconditioner> Prec = Teuchos::rcp( Factory.Create(PrecType, &*A, OverlapLevel) );
84  assert(Prec != Teuchos::null);
85 
86  // specify parameters for ILU
87  List.set("fact: drop tolerance", 1e-9);
88  List.set("fact: level-of-fill", 1);
89  // the combine mode is on the following:
90  // "Add", "Zero", "Insert", "InsertAdd", "Average", "AbsMax"
91  // Their meaning is as defined in file Epetra_CombineMode.h
92  List.set("schwarz: combine mode", "Add");
93  // sets the parameters
94  IFPACK_CHK_ERR(Prec->SetParameters(List));
95 
96  // initialize the preconditioner. At this point the matrix must
97  // have been FillComplete()'d, but actual values are ignored.
98  IFPACK_CHK_ERR(Prec->Initialize());
99 
100  // Builds the preconditioners, by looking for the values of
101  // the matrix.
102  IFPACK_CHK_ERR(Prec->Compute());
103 
104  // =================================================== //
105  // E N D O F I F P A C K C O N S T R U C T I O N //
106  // =================================================== //
107 
108  // At this point, we need some additional objects
109  // to define and solve the linear system.
110 
111  // defines LHS and RHS
112  Epetra_Vector LHS(A->OperatorDomainMap());
113  Epetra_Vector RHS(A->OperatorDomainMap());
114 
115  // solution is constant
116  LHS.PutScalar(1.0);
117  // now build corresponding RHS
118  A->Apply(LHS,RHS);
119 
120  // now randomize the solution
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_gmres);
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  Solver.Iterate(1550,1e-8);
138 
139  std::cout << *Prec;
140 
141 #ifdef HAVE_MPI
142  MPI_Finalize() ;
143 #endif
144 
145  return(EXIT_SUCCESS);
146 }
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Definition: Ifpack.h:144
static Ifpack_Preconditioner * Create(EPrecType PrecType, Epetra_RowMatrix *Matrix, const int overlap=0, bool overrideSerialDefault=false)
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#define RHS(a)
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