Ifpack2 Templated Preconditioning Package Version 1.0
Ifpack2::ILUT< MatrixType > Class Template Reference

ILUT (incomplete LU factorization with threshold) of a Tpetra sparse matrix. More...

#include <Ifpack2_ILUT_decl.hpp>

Inheritance diagram for Ifpack2::ILUT< MatrixType >:
Inheritance graph
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List of all members.

Public Member Functions

Constructors and Destructors
 ILUT (const Teuchos::RCP< const row_matrix_type > &A)
 Constructor.
virtual ~ILUT ()
 Destructor.
Methods for setting up and computing the incomplete factorization
void setParameters (const Teuchos::ParameterList &params)
 Set preconditioner parameters.
void initialize ()
 Clear any previously computed factors.
bool isInitialized () const
 Returns true if the preconditioner has been successfully initialized.
void compute ()
 Compute factors L and U using the specified diagonal perturbation thresholds and relaxation parameters.
bool isComputed () const
 If compute() is completed, this query returns true, otherwise it returns false.
Implementation of Ifpack2::Details::CanChangeMatrix
virtual void setMatrix (const Teuchos::RCP< const row_matrix_type > &A)
 Change the matrix to be preconditioned.
Implementation of Tpetra::Operator
void apply (const Tpetra::MultiVector< scalar_type, local_ordinal_type, global_ordinal_type, node_type > &X, Tpetra::MultiVector< scalar_type, local_ordinal_type, global_ordinal_type, node_type > &Y, Teuchos::ETransp mode=Teuchos::NO_TRANS, scalar_type alpha=Teuchos::ScalarTraits< scalar_type >::one(), scalar_type beta=Teuchos::ScalarTraits< scalar_type >::zero()) const
 Apply the ILUT preconditioner to X, resulting in Y.
Teuchos::RCP< const map_typegetDomainMap () const
 Tpetra::Map representing the domain of this operator.
Teuchos::RCP< const map_typegetRangeMap () const
 Tpetra::Map representing the range of this operator.
bool hasTransposeApply () const
 Whether this object's apply() method can apply the transpose (or conjugate transpose, if applicable).
Mathematical functions
virtual magnitude_type
TEUCHOS_DEPRECATED 
computeCondEst (CondestType CT=Cheap, local_ordinal_type MaxIters=1550, magnitude_type Tol=1e-9, const Teuchos::Ptr< const Tpetra::RowMatrix< scalar_type, local_ordinal_type, global_ordinal_type, node_type > > &Matrix_in=Teuchos::null)
 Compute the condition number estimate and return its value.
virtual magnitude_type
TEUCHOS_DEPRECATED 
getCondEst () const
 Return the computed condition number estimate, or -1 if not computed.
Teuchos::RCP< const
Teuchos::Comm< int > > 
getComm () const
 Returns the input matrix's communicator.
Teuchos::RCP< const
row_matrix_type
getMatrix () const
 Returns a reference to the matrix to be preconditioned.
Teuchos::RCP< const
crs_matrix_type
getL () const
 Returns a reference to the L factor.
Teuchos::RCP< const
crs_matrix_type
getU () const
 Returns a reference to the U factor.
int getNumInitialize () const
 Returns the number of calls to Initialize().
int getNumCompute () const
 Returns the number of calls to Compute().
int getNumApply () const
 Returns the number of calls to apply().
double getInitializeTime () const
 Returns the time spent in Initialize().
double getComputeTime () const
 Returns the time spent in Compute().
double getApplyTime () const
 Returns the time spent in apply().
int getLevelOfFill () const
 The level of fill.
magnitude_type getAbsoluteThreshold () const
 Get absolute threshold value.
magnitude_type getRelativeThreshold () const
 Get relative threshold value.
magnitude_type getRelaxValue () const
 Get the relax value.
magnitude_type getDropTolerance () const
 Gets the dropping tolerance.
global_size_t getGlobalNumEntries () const
 Returns the number of nonzero entries in the global graph.
size_t getNodeNumEntries () const
 Returns the number of nonzero entries in the local graph.
Implementation of Teuchos::Describable
std::string description () const
 Return a simple one-line description of this object.
void describe (Teuchos::FancyOStream &out, const Teuchos::EVerbosityLevel verbLevel=Teuchos::Describable::verbLevel_default) const
 Print the object with some verbosity level to an FancyOStream object.

Typedefs

typedef MatrixType::scalar_type scalar_type
 The type of the entries of the input MatrixType.
typedef
MatrixType::local_ordinal_type 
local_ordinal_type
 The type of local indices in the input MatrixType.
typedef
MatrixType::global_ordinal_type 
global_ordinal_type
 The type of global indices in the input MatrixType.
typedef MatrixType::node_type node_type
 The type of the Kokkos Node used by the input MatrixType.
typedef Teuchos::ScalarTraits
< scalar_type >::magnitudeType 
magnitude_type
 The type of the magnitude (absolute value) of a matrix entry.
typedef Tpetra::RowMatrix
< scalar_type,
local_ordinal_type,
global_ordinal_type, node_type
row_matrix_type
 Type of the Tpetra::RowMatrix specialization that this class uses.
typedef Tpetra::CrsMatrix
< scalar_type,
local_ordinal_type,
global_ordinal_type, node_type
crs_matrix_type
 Type of the Tpetra::CrsMatrix specialization that this class uses for the L and U factors.
typedef Tpetra::Map
< local_ordinal_type,
global_ordinal_type, node_type
map_type
 Type of the Tpetra::Map specialization that this class uses.
TEUCHOS_DEPRECATED typedef
MatrixType::scalar_type 
Scalar
 Preserved only for backwards compatibility. Please use "scalar_type".
TEUCHOS_DEPRECATED typedef
MatrixType::local_ordinal_type 
LocalOrdinal
 Preserved only for backwards compatibility. Please use "local_ordinal_type".
TEUCHOS_DEPRECATED typedef
MatrixType::global_ordinal_type 
GlobalOrdinal
 Preserved only for backwards compatibility. Please use "global_ordinal_type".
TEUCHOS_DEPRECATED typedef
MatrixType::node_type 
Node
 Preserved only for backwards compatibility. Please use "node_type".
TEUCHOS_DEPRECATED typedef
Teuchos::ScalarTraits
< scalar_type >::magnitudeType 
magnitudeType
 Preserved only for backwards compatibility. Please use "magnitude_type".

Detailed Description

template<class MatrixType>
class Ifpack2::ILUT< MatrixType >

ILUT (incomplete LU factorization with threshold) of a Tpetra sparse matrix.

Template Parameters:
Specializationof Tpetra::RowMatrix (preferred) or Tpetra::CrsMatrix

This class computes a sparse ILUT (incomplete LU) factorization with specified fill and drop tolerance, of the local part of a given sparse matrix represented as a Tpetra::RowMatrix or Tpetra::CrsMatrix. The "local part" is the square diagonal block of the matrix owned by the calling process. Thus, if the input matrix is distributed over multiple MPI processes, this preconditioner is equivalent to nonoverlapping additive Schwarz domain decomposition over the MPI processes, with ILUT as the subdomain solver on each process.

See the documentation of setParameters() for a list of valid parameters.

This version of ILUT is a translation of Aztec's ILUT implementation, which was written by Ray Tuminaro.


Member Typedef Documentation

template<class MatrixType>
typedef MatrixType::scalar_type Ifpack2::ILUT< MatrixType >::scalar_type

The type of the entries of the input MatrixType.

template<class MatrixType>
typedef MatrixType::local_ordinal_type Ifpack2::ILUT< MatrixType >::local_ordinal_type

The type of local indices in the input MatrixType.

template<class MatrixType>
typedef MatrixType::global_ordinal_type Ifpack2::ILUT< MatrixType >::global_ordinal_type

The type of global indices in the input MatrixType.

template<class MatrixType>
typedef MatrixType::node_type Ifpack2::ILUT< MatrixType >::node_type

The type of the Kokkos Node used by the input MatrixType.

template<class MatrixType>
typedef Teuchos::ScalarTraits<scalar_type>::magnitudeType Ifpack2::ILUT< MatrixType >::magnitude_type
template<class MatrixType>
typedef Tpetra::RowMatrix<scalar_type, local_ordinal_type, global_ordinal_type, node_type> Ifpack2::ILUT< MatrixType >::row_matrix_type

Type of the Tpetra::RowMatrix specialization that this class uses.

template<class MatrixType>
typedef Tpetra::CrsMatrix<scalar_type, local_ordinal_type, global_ordinal_type, node_type> Ifpack2::ILUT< MatrixType >::crs_matrix_type

Type of the Tpetra::CrsMatrix specialization that this class uses for the L and U factors.

template<class MatrixType>
typedef Tpetra::Map<local_ordinal_type, global_ordinal_type, node_type> Ifpack2::ILUT< MatrixType >::map_type

Type of the Tpetra::Map specialization that this class uses.


Constructor & Destructor Documentation

template<class MatrixType >
Ifpack2::ILUT< MatrixType >::ILUT ( const Teuchos::RCP< const row_matrix_type > &  A) [explicit]

Constructor.

Parameters:
A[in] The sparse matrix to factor, as a Tpetra::RowMatrix. (Tpetra::CrsMatrix inherits from this, so you may use a Tpetra::CrsMatrix here instead.)

The factorization will not modify the input matrix. It stores the L and U factors in the incomplete factorization separately.

template<class MatrixType >
Ifpack2::ILUT< MatrixType >::~ILUT ( ) [virtual]

Destructor.


Member Function Documentation

template<class MatrixType >
void Ifpack2::ILUT< MatrixType >::setParameters ( const Teuchos::ParameterList params) [virtual]

Set preconditioner parameters.

ILUT implements the following parameters:

  • "fact: ilut level-of-fill" (int)
  • "fact: drop tolerance" (magnitude_type)
  • "fact: absolute threshold" (magnitude_type)
  • "fact: relative threshold" (magnitude_type)
  • "fact: relax value" (magnitude_type)

"fact: drop tolerance" is the magnitude threshold for dropping entries. It corresponds to the \(\tau\) parameter in Saad's original description of ILUT. "fact: ilut level-of-fill" is the number of entries to keep in the strict upper triangle of the current row, and in the strict lower triangle of the current row. It corresponds to the \(p\) parameter in Saad's original description. ILUT always keeps the diagonal entry in the current row, regardless of the drop tolerance or fill level.

The absolute and relative threshold parameters affect how this code modifies the diagonal entry of the output factor. These parameters are not part of the original ILUT algorithm, but we include them for consistency with other Ifpack2 preconditioners.

The "fact: relax value" parameter currently has no effect.

Implements Ifpack2::Preconditioner< MatrixType::scalar_type, MatrixType::local_ordinal_type, MatrixType::global_ordinal_type, MatrixType::node_type >.

template<class MatrixType >
void Ifpack2::ILUT< MatrixType >::initialize ( ) [virtual]

Clear any previously computed factors.

You may call this before calling compute(). The compute() method will call this automatically if it has not yet been called. If you call this after calling compute(), you must recompute the factorization (by calling compute() again) before you may call apply().

Implements Ifpack2::Preconditioner< MatrixType::scalar_type, MatrixType::local_ordinal_type, MatrixType::global_ordinal_type, MatrixType::node_type >.

template<class MatrixType>
bool Ifpack2::ILUT< MatrixType >::isInitialized ( ) const [inline, virtual]
template<class MatrixType >
void Ifpack2::ILUT< MatrixType >::compute ( ) [virtual]

Compute factors L and U using the specified diagonal perturbation thresholds and relaxation parameters.

This function computes the ILUT factors L and U using the current:

  1. Value for the drop tolerance
  2. Value for the level of fill
  3. Value for the a priori diagonal threshold values.

Implements Ifpack2::Preconditioner< MatrixType::scalar_type, MatrixType::local_ordinal_type, MatrixType::global_ordinal_type, MatrixType::node_type >.

template<class MatrixType>
bool Ifpack2::ILUT< MatrixType >::isComputed ( ) const [inline, virtual]
template<class MatrixType >
void Ifpack2::ILUT< MatrixType >::setMatrix ( const Teuchos::RCP< const row_matrix_type > &  A) [virtual]

Change the matrix to be preconditioned.

Parameters:
A[in] The new matrix.
Postcondition:
! isInitialized ()
! isComputed ()

Calling this method resets the preconditioner's state. After calling this method with a nonnull input, you must first call initialize() and compute() (in that order) before you may call apply().

You may call this method with a null input. If A is null, then you may not call initialize() or compute() until you first call this method again with a nonnull input. This method invalidates any previous factorization whether or not A is null, so calling setMatrix() with a null input is one way to clear the preconditioner's state (and free any memory that it may be using).

The new matrix A need not necessarily have the same Maps or even the same communicator as the original matrix.

template<class MatrixType >
void Ifpack2::ILUT< MatrixType >::apply ( const Tpetra::MultiVector< scalar_type, local_ordinal_type, global_ordinal_type, node_type > &  X,
Tpetra::MultiVector< scalar_type, local_ordinal_type, global_ordinal_type, node_type > &  Y,
Teuchos::ETransp  mode = Teuchos::NO_TRANS,
scalar_type  alpha = Teuchos::ScalarTraits<scalar_type>::one(),
scalar_type  beta = Teuchos::ScalarTraits<scalar_type>::zero() 
) const [virtual]

Apply the ILUT preconditioner to X, resulting in Y.

Parameters:
X[in] Input multivector; "right-hand side" of the solve.
Y[out] Output multivector; result of the solve.

Implements Ifpack2::Preconditioner< MatrixType::scalar_type, MatrixType::local_ordinal_type, MatrixType::global_ordinal_type, MatrixType::node_type >.

template<class MatrixType >
Teuchos::RCP< const typename ILUT< MatrixType >::map_type > Ifpack2::ILUT< MatrixType >::getDomainMap ( ) const [virtual]
template<class MatrixType >
Teuchos::RCP< const typename ILUT< MatrixType >::map_type > Ifpack2::ILUT< MatrixType >::getRangeMap ( ) const [virtual]
template<class MatrixType >
bool Ifpack2::ILUT< MatrixType >::hasTransposeApply ( ) const

Whether this object's apply() method can apply the transpose (or conjugate transpose, if applicable).

template<class MatrixType>
virtual magnitude_type TEUCHOS_DEPRECATED Ifpack2::ILUT< MatrixType >::computeCondEst ( CondestType  CT = Cheap,
local_ordinal_type  MaxIters = 1550,
magnitude_type  Tol = 1e-9,
const Teuchos::Ptr< const Tpetra::RowMatrix< scalar_type, local_ordinal_type, global_ordinal_type, node_type > > &  Matrix_in = Teuchos::null 
) [virtual]

Compute the condition number estimate and return its value.

Warning:
This method is DEPRECATED. It was inherited from Ifpack, and Ifpack never clearly stated what this method computes. Furthermore, Ifpack's method just estimates the condition number of the matrix A, and ignores the preconditioner -- which is probably not what users thought it did. If there is sufficient interest, we might reintroduce this method with a different meaning and a better algorithm.

Implements Ifpack2::Preconditioner< MatrixType::scalar_type, MatrixType::local_ordinal_type, MatrixType::global_ordinal_type, MatrixType::node_type >.

template<class MatrixType>
virtual magnitude_type TEUCHOS_DEPRECATED Ifpack2::ILUT< MatrixType >::getCondEst ( ) const [inline, virtual]

Return the computed condition number estimate, or -1 if not computed.

Warning:
This method is DEPRECATED. See warning for computeCondEst().

Implements Ifpack2::Preconditioner< MatrixType::scalar_type, MatrixType::local_ordinal_type, MatrixType::global_ordinal_type, MatrixType::node_type >.

template<class MatrixType >
Teuchos::RCP< const Teuchos::Comm< int > > Ifpack2::ILUT< MatrixType >::getComm ( ) const

Returns the input matrix's communicator.

template<class MatrixType >
Teuchos::RCP< const typename ILUT< MatrixType >::row_matrix_type > Ifpack2::ILUT< MatrixType >::getMatrix ( ) const [virtual]
template<class MatrixType>
Teuchos::RCP<const crs_matrix_type> Ifpack2::ILUT< MatrixType >::getL ( ) const [inline]

Returns a reference to the L factor.

template<class MatrixType>
Teuchos::RCP<const crs_matrix_type> Ifpack2::ILUT< MatrixType >::getU ( ) const [inline]

Returns a reference to the U factor.

template<class MatrixType >
int Ifpack2::ILUT< MatrixType >::getNumInitialize ( ) const [virtual]
template<class MatrixType >
int Ifpack2::ILUT< MatrixType >::getNumCompute ( ) const [virtual]
template<class MatrixType >
int Ifpack2::ILUT< MatrixType >::getNumApply ( ) const [virtual]
template<class MatrixType >
double Ifpack2::ILUT< MatrixType >::getInitializeTime ( ) const [virtual]
template<class MatrixType >
double Ifpack2::ILUT< MatrixType >::getComputeTime ( ) const [virtual]
template<class MatrixType >
double Ifpack2::ILUT< MatrixType >::getApplyTime ( ) const [virtual]
template<class MatrixType>
int Ifpack2::ILUT< MatrixType >::getLevelOfFill ( ) const [inline]

The level of fill.

For ILUT, this means the maximum number of entries in each row of the resulting L and U factors (each considered separately), not including the diagonal entry in that row (which is always part of U). This has a different meaning for ILUT than it does for ILU(k).

template<class MatrixType>
magnitude_type Ifpack2::ILUT< MatrixType >::getAbsoluteThreshold ( ) const [inline]

Get absolute threshold value.

template<class MatrixType>
magnitude_type Ifpack2::ILUT< MatrixType >::getRelativeThreshold ( ) const [inline]

Get relative threshold value.

template<class MatrixType>
magnitude_type Ifpack2::ILUT< MatrixType >::getRelaxValue ( ) const [inline]

Get the relax value.

template<class MatrixType>
magnitude_type Ifpack2::ILUT< MatrixType >::getDropTolerance ( ) const [inline]

Gets the dropping tolerance.

template<class MatrixType >
global_size_t Ifpack2::ILUT< MatrixType >::getGlobalNumEntries ( ) const

Returns the number of nonzero entries in the global graph.

template<class MatrixType >
size_t Ifpack2::ILUT< MatrixType >::getNodeNumEntries ( ) const

Returns the number of nonzero entries in the local graph.

template<class MatrixType >
std::string Ifpack2::ILUT< MatrixType >::description ( ) const

Return a simple one-line description of this object.

template<class MatrixType >
void Ifpack2::ILUT< MatrixType >::describe ( Teuchos::FancyOStream out,
const Teuchos::EVerbosityLevel  verbLevel = Teuchos::Describable::verbLevel_default 
) const

Print the object with some verbosity level to an FancyOStream object.


Member Data Documentation

template<class MatrixType>
TEUCHOS_DEPRECATED typedef MatrixType::scalar_type Ifpack2::ILUT< MatrixType >::Scalar

Preserved only for backwards compatibility. Please use "scalar_type".

template<class MatrixType>
TEUCHOS_DEPRECATED typedef MatrixType::local_ordinal_type Ifpack2::ILUT< MatrixType >::LocalOrdinal

Preserved only for backwards compatibility. Please use "local_ordinal_type".

template<class MatrixType>
TEUCHOS_DEPRECATED typedef MatrixType::global_ordinal_type Ifpack2::ILUT< MatrixType >::GlobalOrdinal

Preserved only for backwards compatibility. Please use "global_ordinal_type".

template<class MatrixType>
TEUCHOS_DEPRECATED typedef MatrixType::node_type Ifpack2::ILUT< MatrixType >::Node

Preserved only for backwards compatibility. Please use "node_type".

template<class MatrixType>
TEUCHOS_DEPRECATED typedef Teuchos::ScalarTraits<scalar_type>::magnitudeType Ifpack2::ILUT< MatrixType >::magnitudeType

Preserved only for backwards compatibility. Please use "magnitude_type".

Reimplemented from Ifpack2::Preconditioner< MatrixType::scalar_type, MatrixType::local_ordinal_type, MatrixType::global_ordinal_type, MatrixType::node_type >.


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