#include <deal.II/lac/trilinos_precondition.h>

Inheritance diagram for TrilinosWrappers::PreconditionAMG:

Classes
struct	AdditionalData

Public Member Functions
	~PreconditionAMG () override

void	initialize (const SparseMatrix &matrix, const AdditionalData &additional_data=AdditionalData())

void	initialize (const Epetra_RowMatrix &matrix, const AdditionalData &additional_data=AdditionalData())

void	initialize (const SparseMatrix &matrix, const Teuchos::ParameterList &ml_parameters)

void	initialize (const Epetra_RowMatrix &matrix, const Teuchos::ParameterList &ml_parameters)

template<typename number >
void	initialize (const ::SparseMatrix< number > &deal_ii_sparse_matrix, const AdditionalData &additional_data=AdditionalData(), const double drop_tolerance=1e-13, const ::SparsityPattern *use_this_sparsity=nullptr)

void	reinit ()

void	clear ()

size_type	memory_consumption () const

Public Member Functions inherited from TrilinosWrappers::PreconditionBase
	PreconditionBase ()

	PreconditionBase (const PreconditionBase &)

	~PreconditionBase () override=default

void	clear ()

MPI_Comm	get_mpi_communicator () const

void	transpose ()

virtual void	vmult (MPI::Vector &dst, const MPI::Vector &src) const

virtual void	Tvmult (MPI::Vector &dst, const MPI::Vector &src) const

virtual void	vmult (::Vector< double > &dst, const ::Vector< double > &src) const

virtual void	Tvmult (::Vector< double > &dst, const ::Vector< double > &src) const

virtual void	vmult (::LinearAlgebra::distributed::Vector< double > &dst, const ::LinearAlgebra::distributed::Vector< double > &src) const

virtual void	Tvmult (::LinearAlgebra::distributed::Vector< double > &dst, const ::LinearAlgebra::distributed::Vector< double > &src) const

Epetra_Operator &	trilinos_operator () const

IndexSet	locally_owned_domain_indices () const

IndexSet	locally_owned_range_indices () const

Public Member Functions inherited from Subscriptor
	Subscriptor ()

	Subscriptor (const Subscriptor &)

	Subscriptor (Subscriptor &&) noexcept

virtual	~Subscriptor ()

Subscriptor &	operator= (const Subscriptor &)

Subscriptor &	operator= (Subscriptor &&) noexcept

void	subscribe (std::atomic< bool > *const validity, const std::string &identifier="") const

void	unsubscribe (std::atomic< bool > *const validity, const std::string &identifier="") const

unsigned int	n_subscriptions () const

template<typename StreamType >
void	list_subscribers (StreamType &stream) const

void	list_subscribers () const

template<class Archive >
void	serialize (Archive &ar, const unsigned int version)

Private Attributes
std::shared_ptr< SparseMatrix >	trilinos_matrix

Additional Inherited Members
Public Types inherited from TrilinosWrappers::PreconditionBase
using	size_type = ::types::global_dof_index

Static Public Member Functions inherited from TrilinosWrappers::PreconditionBase
static ::ExceptionBase &	ExcNonMatchingMaps (std::string arg1)

Static Public Member Functions inherited from Subscriptor
static ::ExceptionBase &	ExcInUse (int arg1, std::string arg2, std::string arg3)

static ::ExceptionBase &	ExcNoSubscriber (std::string arg1, std::string arg2)

Protected Attributes inherited from TrilinosWrappers::PreconditionBase
Teuchos::RCP< Epetra_Operator >	preconditioner

Epetra_MpiComm	communicator

std::shared_ptr< Epetra_Map >	vector_distributor

Detailed Description

This class implements an algebraic multigrid (AMG) preconditioner based on the Trilinos ML implementation, which is a black-box preconditioner that works well for many PDE-based linear problems. What this class does is twofold. When the initialize() function is invoked, a ML preconditioner object is created based on the matrix that we want the preconditioner to be based on. A call of the respective vmult function does call the respective operation in the Trilinos package, where it is called ApplyInverse. Use of this class is explained in the step-31 tutorial program.

Since the Trilinos objects we want to use are heavily dependent on Epetra objects, we recommend using this class in conjunction with Trilinos (Epetra) sparse matrices and vectors. There is support for use with matrices of the SparseMatrix class and corresponding vectors, too, but this requires generating a copy of the matrix, which is slower and takes (much) more memory. When doing such a copy operation, we can still profit from the fact that some of the entries in the preconditioner matrix are zero and hence can be neglected.

The implementation is able to distinguish between matrices from elliptic problems and convection dominated problems. We use the standard options provided by Trilinos ML for elliptic problems, except that we use a Chebyshev smoother instead of a symmetric Gauss-Seidel smoother. For most elliptic problems, Chebyshev provides a better damping of high frequencies (in the algebraic sense) than Gauss-Seidel (SSOR), and is faster (Chebyshev requires only some matrix-vector products, whereas SSOR requires substitutions which are more expensive). Moreover, Chebyshev is perfectly parallel in the sense that it does not degenerate when used on many processors. SSOR, on the other hand, gets more Jacobi-like on many processors.

For proper functionality of this class we recommend using Trilinos v9.0 and higher. Older versions may have problems with generating the coarse- matrix structure when using matrices with many nonzero entries per row (i.e., matrices stemming from higher order finite element discretizations).

Author: Martin Kronbichler, 2008

Definition at line 1361 of file trilinos_precondition.h.

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

include/deal.II/lac/trilinos_precondition.h
source/lac/trilinos_precondition_ml.cc

Classes

Public Member Functions

Private Attributes

Additional Inherited Members

Detailed Description