Reference documentation for deal.II version GIT 6da2e5d553 2022-07-01 18:55:02+00:00
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Classes | Public Types | Public Member Functions | Private Attributes | List of all members

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

Inheritance diagram for TrilinosWrappers::PreconditionAMG:
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Classes

struct  AdditionalData
 

Public Types

using size_type = ::types::global_dof_index
 

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
 
MPI_Comm get_mpi_communicator () const
 
void transpose ()
 
virtual void vmult (MPI::Vector &dst, const MPI::Vector &src) const
 
virtual void vmult (::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 (MPI::Vector &dst, const MPI::Vector &src) const
 
virtual void Tvmult (::Vector< double > &dst, const ::Vector< double > &src) const
 
virtual void Tvmult (::LinearAlgebra::distributed::Vector< double > &dst, const ::LinearAlgebra::distributed::Vector< double > &src) const
 
Access to underlying Trilinos data
Epetra_Operatortrilinos_operator () const
 

Private Attributes

std::shared_ptr< SparseMatrixtrilinos_matrix
 

Subscriptor functionality

Classes derived from Subscriptor provide a facility to subscribe to this object. This is mostly used by the SmartPointer class.

std::atomic< unsigned int > counter
 
std::map< std::string, unsigned int > counter_map
 
std::vector< std::atomic< bool > * > validity_pointers
 
const std::type_info * object_info
 
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)
 
static ::ExceptionBaseExcInUse (int arg1, std::string arg2, std::string arg3)
 
static ::ExceptionBaseExcNoSubscriber (std::string arg1, std::string arg2)
 
using map_value_type = decltype(counter_map)::value_type
 
using map_iterator = decltype(counter_map)::iterator
 
static std::mutex mutex
 
void check_no_subscribers () const noexcept
 

Partitioners

IndexSet locally_owned_domain_indices () const
 
IndexSet locally_owned_range_indices () const
 
Teuchos::RCP< Epetra_Operatorpreconditioner
 
Epetra_MpiComm communicator
 
std::shared_ptr< Epetra_Map > vector_distributor
 
static ::ExceptionBaseExcNonMatchingMaps (std::string arg1)
 

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).

Definition at line 1336 of file trilinos_precondition.h.


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