Ifpack2::Partitioner< GraphType > Class Template Reference

Ifpack2::Partitioner: A class to decompose local Ifpack2::Graph objects. More...

#include <Ifpack2_Partitioner.hpp>

Inheritance diagram for Ifpack2::Partitioner< GraphType >:

List of all members.

Public Member Functions
virtual	~Partitioner ()
	Destructor.
virtual size_t	numLocalParts () const =0
	Returns the number of computed local partitions.
virtual size_t	overlappingLevel () const =0
	Returns the overlapping level.
virtual LocalOrdinal	operator() (LocalOrdinal MyRow) const =0
	Returns the local non-overlapping partition ID of the specified row.
virtual LocalOrdinal	operator() (LocalOrdinal i, LocalOrdinal j) const =0
	Returns the local overlapping partition ID of the j-th node in partition i.
virtual size_t	numRowsInPart (const LocalOrdinal Part) const =0
	Returns the number of rows contained in specified partition.
virtual void	rowsInPart (const LocalOrdinal Part, Teuchos::ArrayRCP< LocalOrdinal > &List) const =0
	Copies into List the rows in the (overlapping) partition Part.
virtual Teuchos::ArrayView < const LocalOrdinal >	nonOverlappingPartition () const =0
	Returns an ArrayRCP to the integer vector containing the non-overlapping partition ID of each local row.
virtual void	setParameters (Teuchos::ParameterList &List)=0
	Sets all the parameters for the partitioner.
virtual void	compute ()=0
	Computes the partitions. Returns 0 if successful.
virtual bool	isComputed () const =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.

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Detailed Description

template<class GraphType>
class Ifpack2::Partitioner< GraphType >

Ifpack2::Partitioner: A class to decompose local Ifpack2::Graph objects.

Class Ifpack2::Partitioner enables the decomposition of a local Ifpack2::Graph. It is supposed that the graph refers to a localized matrix (that is, a matrix that has been filtered through Ifpack2::LocalFilter).

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

The partitions created by Ifpack2::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 Ifpack2_OverlappingPartitioner (itself derived from Ifpack2_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).

Ifpack2::Partitioner is a pure virtual class. Concrete implementations are:

• Ifpack2_LinearPartitioner, which allows the decomposition of the rows of the graph in simple consecutive chunks;
• Ifpack2_Zoltan2Partitioner, which calls Zoltan2 to decompose the graph

Generically, a constructor requires a Tpetra::RowGraph object.

An example use of a Ifpack2::Partitioner derived class is as follows:

#include "Ifpack2_Partitioner.hpp"
#include "Ifpack2_LinearPartitioner.hpp"
#include "Ifpack2_Graph.hpp"
#include "Ifpack2_Graph_Tpetra_CrsGraph.hpp"
...
Tpetra_CrsMatrix* A;         // A is filled
// create the wrapper from Tpetra_CrsGraph
Ifpack2_Graph* Graph = new Ifpack2_Graph_Tpetra_CrsGraph(A);

// we aim to create non-overlapping partitions only
Ifpack2_Partitioner Partitioner(Graph);

Ifpack2_Partitioner* Partitioner;
Partitioner = new Ifpack2_Graph_Tpetra_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
Partitioner.Create(List);

// 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;
  }
}  

Ifpack2_Partitioner is used to create the subblocks in Ifpack2_BlockJacobi, Ifpack2_BlockGaussSeidel, and Ifpack2_BlockSymGaussSeidel.

Author:

Michael Heroux, SNL 9214.

Date:

Last modified on Nov-04.

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Constructor & Destructor Documentation

template<class GraphType >

virtual Ifpack2::Partitioner< GraphType >::~Partitioner

(

)

[inline, virtual]

Destructor.

---

Member Function Documentation

template<class GraphType >

virtual size_t Ifpack2::Partitioner< GraphType >::numLocalParts

(

)

const [pure virtual]

Returns the number of computed local partitions.

template<class GraphType >

virtual size_t Ifpack2::Partitioner< GraphType >::overlappingLevel

(

)

const [pure virtual]

Returns the overlapping level.

template<class GraphType >

virtual LocalOrdinal Ifpack2::Partitioner< GraphType >::operator()

(

LocalOrdinal

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.

Parameters:

MyRow

- (In) local row number

Returns:

Local ID of non-overlapping partition for MyRow.

template<class GraphType >

virtual LocalOrdinal Ifpack2::Partitioner< GraphType >::operator()	(	LocalOrdinal	i,
		LocalOrdinal	j
	)		const [pure virtual]

Returns the local overlapping partition ID of the j-th node in partition i.

template<class GraphType >

virtual size_t Ifpack2::Partitioner< GraphType >::numRowsInPart

(

const LocalOrdinal

Part

)

const [pure virtual]

Returns the number of rows contained in specified partition.

template<class GraphType >

virtual void Ifpack2::Partitioner< GraphType >::rowsInPart	(	const LocalOrdinal	Part,
		Teuchos::ArrayRCP< LocalOrdinal > &	List
	)		const [pure virtual]

Copies into List the rows in the (overlapping) partition Part.

template<class GraphType >

virtual Teuchos::ArrayView<const LocalOrdinal> Ifpack2::Partitioner< GraphType >::nonOverlappingPartition

(

)

const [pure virtual]

Returns an ArrayRCP to the integer vector containing the non-overlapping partition ID of each local row.

template<class GraphType >

virtual void Ifpack2::Partitioner< GraphType >::setParameters

(

Teuchos::ParameterList &

List

)

[pure virtual]

Sets all the parameters for the partitioner.

template<class GraphType >

virtual void Ifpack2::Partitioner< GraphType >::compute

(

)

[pure virtual]

Computes the partitions. Returns 0 if successful.

template<class GraphType >

virtual bool Ifpack2::Partitioner< GraphType >::isComputed

(

)

const [pure virtual]

Returns true if partitions have been computed successfully.

template<class GraphType >

virtual std::ostream& Ifpack2::Partitioner< GraphType >::print

(

std::ostream &

os

)

const [pure virtual]

Prints basic information about the partitioning object.

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

• Ifpack2_Partitioner.hpp