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Ifpack_ex_Factory.cpp
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41 
42 #include "Ifpack_ConfigDefs.h"
43 
44 #ifdef HAVE_MPI
45 #include "Epetra_MpiComm.h"
46 #else
47 #include "Epetra_SerialComm.h"
48 #endif
49 #include "Epetra_CrsMatrix.h"
50 #include "Epetra_MultiVector.h"
51 #include "Epetra_LinearProblem.h"
52 #include "Galeri_Maps.h"
53 #include "Galeri_CrsMatrices.h"
54 #include "Teuchos_ParameterList.hpp"
55 #include "Teuchos_RefCountPtr.hpp"
56 #include "AztecOO.h"
57 #include "Ifpack.h"
58 #include "Ifpack_AdditiveSchwarz.h"
59 
60 int main(int argc, char *argv[])
61 {
62 
63 #ifdef HAVE_MPI
64  MPI_Init(&argc,&argv);
65  Epetra_MpiComm Comm( MPI_COMM_WORLD );
66 #else
67  Epetra_SerialComm Comm;
68 #endif
69 
70  Teuchos::ParameterList GaleriList;
71 
72  // The problem is defined on a 2D grid, global size is nx * nx.
73  int nx = 30;
74  GaleriList.set("n", nx * nx);
75  GaleriList.set("nx", nx);
76  GaleriList.set("ny", nx);
77  Teuchos::RefCountPtr<Epetra_Map> Map = Teuchos::rcp( Galeri::CreateMap("Linear", Comm, GaleriList) );
78  Teuchos::RefCountPtr<Epetra_RowMatrix> A = Teuchos::rcp( Galeri::CreateCrsMatrix("Laplace2D", &*Map, GaleriList) );
79 
80  // =============================================================== //
81  // 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 //
82  // =============================================================== //
83 
85 
86  // allocates an IFPACK factory. No data is associated
87  // to this object (only method Create()).
88  Ifpack Factory;
89 
90  // create the preconditioner. For valid PrecType values,
91  // please check the documentation
92  std::string PrecType = "ILU"; // incomplete LU
93  int OverlapLevel = 1; // must be >= 0. If Comm.NumProc() == 1,
94  // it is ignored.
95 
96  Teuchos::RefCountPtr<Ifpack_Preconditioner> Prec = Teuchos::rcp( Factory.Create(PrecType, &*A, OverlapLevel) );
97  assert(Prec != Teuchos::null);
98 
99  // specify parameters for ILU
100  List.set("fact: drop tolerance", 1e-9);
101  List.set("fact: level-of-fill", 1);
102  // the combine mode is on the following:
103  // "Add", "Zero", "Insert", "InsertAdd", "Average", "AbsMax"
104  // Their meaning is as defined in file Epetra_CombineMode.h
105  List.set("schwarz: combine mode", "Add");
106  // sets the parameters
107  IFPACK_CHK_ERR(Prec->SetParameters(List));
108 
109  // initialize the preconditioner. At this point the matrix must
110  // have been FillComplete()'d, but actual values are ignored.
111  IFPACK_CHK_ERR(Prec->Initialize());
112 
113  // Builds the preconditioners, by looking for the values of
114  // the matrix.
115  IFPACK_CHK_ERR(Prec->Compute());
116 
117  // =================================================== //
118  // E N D O F I F P A C K C O N S T R U C T I O N //
119  // =================================================== //
120 
121  // At this point, we need some additional objects
122  // to define and solve the linear system.
123 
124  // defines LHS and RHS
125  Epetra_Vector LHS(A->OperatorDomainMap());
126  Epetra_Vector RHS(A->OperatorDomainMap());
127 
128  // solution is constant
129  LHS.PutScalar(1.0);
130  // now build corresponding RHS
131  A->Apply(LHS,RHS);
132 
133  // now randomize the solution
134  RHS.Random();
135 
136  // need an Epetra_LinearProblem to define AztecOO solver
137  Epetra_LinearProblem Problem(&*A,&LHS,&RHS);
138 
139  // now we can allocate the AztecOO solver
140  AztecOO Solver(Problem);
141 
142  // specify solver
143  Solver.SetAztecOption(AZ_solver,AZ_gmres);
144  Solver.SetAztecOption(AZ_output,32);
145 
146  // HERE WE SET THE IFPACK PRECONDITIONER
147  Solver.SetPrecOperator(&*Prec);
148 
149  // .. and here we solve
150  Solver.Iterate(1550,1e-8);
151 
152  std::cout << *Prec;
153 
154 #ifdef HAVE_MPI
155  MPI_Finalize() ;
156 #endif
157 
158  return(EXIT_SUCCESS);
159 }
ParameterList & set(std::string const &name, T &&value, std::string const &docString="", RCP< const ParameterEntryValidator > const &validator=null)
static bool Solver
Definition: performance.cpp:70
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Ifpack: a function class to define Ifpack preconditioners.
Definition: Ifpack.h:144
static Ifpack_Preconditioner * Create(EPrecType PrecType, Epetra_RowMatrix *Matrix, const int overlap=0, bool overrideSerialDefault=false)
Creates an instance of Ifpack_Preconditioner given the enum value of the preconditioner type (can not...
Definition: Ifpack.cpp:253
#define IFPACK_CHK_ERR(ifpack_err)
#define RHS(a)
Definition: MatGenFD.c:60