Isorropia Probing Methods

Here we describe the probing interface provided by Isorropia. More...

Classes
class	Isorropia::Epetra::Prober
	An implementation of the Prober interface that operates on Epetra matrices and linear systems. More...

Functions
	Isorropia::Epetra::Prober::Prober (Teuchos::RCP< const Epetra_CrsGraph > input_graph, const Teuchos::ParameterList &paramlist, bool compute_now=true)
	Constructor. More...
	Isorropia::Epetra::Prober::Prober (const Epetra_CrsGraph *input_graph, const Teuchos::ParameterList &paramlist, bool compute_now=true)
	Constructor. More...
	Isorropia::Epetra::Prober::Prober (Teuchos::RCP< const Epetra_CrsMatrix > input_matrix, const Teuchos::ParameterList &paramlist, bool compute_now=true)
	Constructor. More...
	Isorropia::Epetra::Prober::Prober (const Epetra_CrsMatrix *input_matrix, const Teuchos::ParameterList &paramlist, bool compute_now=true)
	Constructor. More...
void	Isorropia::Epetra::Prober::color ()
	Compute the coloring. More...
int	Isorropia::Epetra::Prober::getNumOrthogonalVectors ()
	Get the number of orthogonal vectors (or the number of colors from coloring) More...
int	Isorropia::Epetra::Prober::probe (const Epetra_Operator &op, Epetra_CrsMatrix &out_matrix)
	Perform the actual probing. More...
Teuchos::RCP< Epetra_CrsMatrix >	Isorropia::Epetra::Prober::probe (const Epetra_Operator &op)
	Perform the actual probing. More...

Detailed Description

Here we describe the probing interface provided by Isorropia.

Probing

Isorropia's distance-2 graph vertex capability enables matrix probing, the re-construction (or approximation) of a matrix from matrix-vector products with specially chosen vectors. These vectors are combinations of columns of the identity which are carefully chosen such that the columns probed by such a vector are structurally orthogonal. The most common use case of probing is when the matrix is not explicitly stored, but the matrix entries are necessary for some other procedure (e.g. preconditioning). In certain applications, an exact reconstruction of the matrix is needed. In others, an approximation based on a priori knowledge of the "significant" matrix entries suffices. Isorropia's probing functionality works in both cases.

Currently, Isorropia's probing functionality is limited to structurally symmetric matrices but we expect to support nonsymmetric matrices (e.g. Jacobians) in the future.

Function Documentation

Isorropia::Epetra::Prober::Prober	(	Teuchos::RCP< const Epetra_CrsGraph >	input_graph,
		const Teuchos::ParameterList &	paramlist,
		bool	compute_now = true
	)

Constructor.

Parameters

[in]	input_graph	the graph whose sparsity pattern is to guide the probing.
[in]	paramlist	this parameter list may be used to pass parameters to the colorer.
[in]	compute_now	if true, the coloring is computed in the constructor, otherwise call Isorropia::Epetra::Prober::color when you want to compute the coloring, defaults to false

Isorropia::Epetra::Prober::Prober	(	const Epetra_CrsGraph *	input_graph,
		const Teuchos::ParameterList &	paramlist,
		bool	compute_now = true
	)

Constructor.

Parameters

[in]	input_graph	the graph whose sparsity pattern is to guide the probing.
[in]	paramlist	this parameter list may be used to pass parameters to the colorer.
[in]	compute_now	if true, the coloring is computed in the constructor, otherwise call Isorropia::Epetra::Prober::color when you want to compute the coloring, defaults to false

Isorropia::Epetra::Prober::Prober	(	Teuchos::RCP< const Epetra_CrsMatrix >	input_matrix,
		const Teuchos::ParameterList &	paramlist,
		bool	compute_now = true
	)

Constructor.

Parameters

[in]	input_matrix	the matrix whose sparsity pattern is to guide the probing.
[in]	paramlist	this parameter list may be used to pass parameters to the colorer.
[in]	compute_now	if true, the coloring is computed in the constructor, otherwise call Isorropia::Epetra::Prober::color when you want to compute the coloring, defaults to true

Isorropia::Epetra::Prober::Prober	(	const Epetra_CrsMatrix *	input_matrix,
		const Teuchos::ParameterList &	paramlist,
		bool	compute_now = true
	)

Constructor.

Parameters

[in]	input_matrix	the matrix whose sparsity pattern is to guide the probing.
[in]	paramlist	this parameter list may be used to pass parameters to the colorer.
[in]	compute_now	if true, the coloring is computed in the constructor, otherwise call Isorropia::Epetra::Prober::color when you want to compute the coloring, defaults to true

void Isorropia::Epetra::Prober::color

(

)

Compute the coloring.

int Isorropia::Epetra::Prober::getNumOrthogonalVectors

(

)

Get the number of orthogonal vectors (or the number of colors from coloring)

Returns

number of orthogonal vectors

int Isorropia::Epetra::Prober::probe	(	const Epetra_Operator &	op,
		Epetra_CrsMatrix &	out_matrix
	)

Perform the actual probing.

Parameters

[in]	op	is the operator we are probing
[in,out]	out_matrix	is the matrix

Teuchos::RCP<Epetra_CrsMatrix> Isorropia::Epetra::Prober::probe

(

const Epetra_Operator &

op

)

Perform the actual probing.

Parameters

[in]

op

is the operator we are probing

Returns

RCP to the matrix