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Ifpack_Partitioner Class Referenceabstract

Ifpack_Partitioner: A class to decompose local Ifpack_Graph's. More...

#include <Ifpack_Partitioner.h>

Inheritance diagram for Ifpack_Partitioner:
Inheritance graph

Public Member Functions

virtual ~Ifpack_Partitioner ()
virtual int NumLocalParts () const =0
 Returns the number of computed local partitions.
virtual int OverlappingLevel () const =0
 Returns the overlapping level.
virtual int operator() (int MyRow) const =0
 Returns the local non-overlapping partition ID of the specified row. More...
virtual int operator() (int i, int j) const =0
 Returns the local overlapping partition ID of the j-th node in partition i.
virtual int NumRowsInPart (const int Part) const =0
 Returns the number of rows contained in specified partition.
virtual int RowsInPart (const int Part, int *List) const =0
 Copies into List the rows in the (overlapping) partition Part.
virtual const int * NonOverlappingPartition () const =0
 Returns a pointer to the integer vector containing the non-overlapping partition ID of each local row.
virtual int SetParameters (Teuchos::ParameterList &List)=0
 Sets all the parameters for the partitioner.
virtual int Compute ()=0
 Computes the partitions. Returns 0 if successful.
virtual bool IsComputed ()=0
 Returns true if partitions have been computed successfully.
virtual std::ostream & Print (std::ostream &os) const =0
 Prints basic information about the partitioning object.

Detailed Description

Ifpack_Partitioner: A class to decompose local Ifpack_Graph's.

Class Ifpack_Partitioner enables the decomposition of a local Ifpack_Graph's. It is supposed that the graph refers to a localized matrix (that is, a matrix that has been filtered through Ifpack_LocalFilter).

The overloaded operator (int i) can be used to extract the local partition ID of local row i.

The partitions created by Ifpack_Partitioner derived clased are non-overlapping in graph sense. This means that each row (or, more approriately, vertex) of G is assigned to exactly one partition.

Partitioner can be extended using the functionalities of class Ifpack_OverlappingPartitioner (itself derived from Ifpack_Partitioner. This class extends the non-overlapping partitions by the required amount of overlap, considering local nodes only (that is, this overlap do not modify the overlap among the processes).

Ifpack_Partitioner is a pure virtual class. Concrete implementations are:

Generically, a constructor requires an Ifpack_Graph object. Ifpack_Graph is a pure virtual class. Concrete implentations are:

An example of use is an Ifpack_Partitioner derived class is as follows:

#include "Ifpack_Partitioner.h"
#include "Ifpack_LinearPartitioner.h"
#include "Ifpack_Graph.h"
#include "Ifpack_Graph_Epetra_CrsGraph.h"
Epetra_CrsMatrix* A; // A is filled
// create the wrapper from Epetra_CrsGraph
// we aim to create non-overlapping partitions only
Ifpack_Partitioner Partitioner(Graph);
Ifpack_Partitioner* Partitioner;
Partitioner = new Ifpack_Graph_Epetra_CrsGraph(&A);
// we want 16 local parts
List.set("partitioner: local parts", 16);
// and an overlap of 0 among the local parts (default option)
List.set("partitioner: overlap", 0);
// decompose the graph
// now Graph can be deleted, as Partitioner contains all the
// necessary information to use the partitions
delete Graph;
// we can get the number of parts actually created...
int NumParts = Partitioner.NumParts();
// ... and the number of rows in each of them
for (int i = 0 ; i < NumParts ; ++i) {
cout << "rows in " << i << "=" << Partitioner.RowsInPart(i);
// .. and, for non-overlapping partitions only, the partition ID
// for each local row simply using:
for (int i = 0 ; i < A->NumMyRows() ; ++i)
cout << "Partition[" << i <<"] = " << Partitioner(i) << endl;

When overlapping partitiones are created, the user can get the row ID contained in each partition as follows:

for (int i = 0 ; i < NumParts ; ++i) {
for (int j = 0 ; j < Partitioner.RowsInPart(i) ; ++j) {
cout << "Partition " << i << ", contains local row "
<< Partitioner(i,j) << endl;

Ifpack_Partitioner is used to create the subblocks in Ifpack_BlockJacobi, Ifpack_BlockGaussSeidel, and Ifpack_BlockSymGaussSeidel.

Marzio Sala, SNL 9214.
Last modified on Nov-04.

Definition at line 162 of file Ifpack_Partitioner.h.

Member Function Documentation

virtual int Ifpack_Partitioner::operator() ( int  MyRow) const
pure virtual

Returns the local non-overlapping partition ID of the specified row.

Returns the non-overlapping partition ID of the specified row.

MyRow- (In) local row numbe
Local ID of non-overlapping partition for MyRow.

Implemented in Ifpack_OverlappingPartitioner.

The documentation for this class was generated from the following file: