Reference documentation for deal.II version Git 5d31222 2015-01-28 23:05:31 +0100
TrilinosWrappers::PreconditionILUT Class Reference

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

Inheritance diagram for TrilinosWrappers::PreconditionILUT:
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## Public Member Functions

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

PreconditionBase (const PreconditionBase &)

~PreconditionBase ()

void clear ()

virtual void vmult (VectorBase &dst, const VectorBase &src) const

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

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

DeclException1 (ExcNonMatchingMaps, std::string,<< "The sparse matrix the preconditioner is based on "<< "uses a map that is not compatible to the one in vector "<< arg1<< ". Check preconditioner and matrix setup.")

Public Member Functions inherited from Subscriptor
Subscriptor ()

Subscriptor (const Subscriptor &)

virtual ~Subscriptor ()

Subscriptoroperator= (const Subscriptor &)

void subscribe (const char *identifier=0) const

void unsubscribe (const char *identifier=0) const

unsigned int n_subscriptions () const

void list_subscribers () const

DeclException3 (ExcInUse, int, char *, std::string &,<< "Object of class "<< arg2<< " is still used by "<< arg1<< " other objects.\n"<< "(Additional information: "<< arg3<< ")\n"<< "Note the entry in the Frequently Asked Questions of "<< "deal.II (linked to from http://www.dealii.org/) for "<< "more information on what this error means.")

DeclException2 (ExcNoSubscriber, char *, char *,<< "No subscriber with identifier \""<< arg2<< "\" did subscribe to this object of class "<< arg1)

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

Public Types inherited from TrilinosWrappers::PreconditionBase
typedef ::types::global_dof_index size_type

Protected Attributes inherited from TrilinosWrappers::PreconditionBase
std_cxx11::shared_ptr
< Epetra_Operator >
preconditioner

Epetra_MpiComm communicator

std_cxx11::shared_ptr< Epetra_Map > vector_distributor

## Detailed Description

A wrapper class for a thresholded incomplete LU factorization (ILU-T) preconditioner for Trilinos matrices. This preconditioner works both in serial and in parallel, depending on the matrix it is based on. In general, an incomplete factorization does not take all fill-in elements that would appear in a full factorization (that is the basis for a direct solve). For the ILU-T precondtioner, the parameter ilut_drop lets the user specify which elements should be dropped (i.e., should not be part of the incomplete decomposition). Trilinos calculates first the complete factorization for one row, and then skips those elements that are lower than the threshold. This is the main difference to the non- thresholded ILU preconditioner, where the parameter ilut_fill governs the incomplete factorization structure. This parameter is available here as well, but provides only some extra information here.

The AdditionalData data structure allows to set preconditioner options. Besides the fill-in arguments, these options are some options for perturbations (see the documentation of the AdditionalData structure for details), and a parameter overlap that determines if and how much overlap there should be between the matrix partitions on the various MPI processes. The default settings are 0 for the additional fill-in, 0 for the absolute augmentation tolerance, 1 for the relative augmentation tolerance, 0 for the overlap.

Note that a parallel application of the ILU-T preconditioner is actually a block-Jacobi preconditioner with block size equal to the local matrix size. Spoken more technically, this parallel operation is an additive Schwarz method with an ILU approximate solve as inner solver, based on the (outer) parallel partitioning.

Definition at line 1035 of file trilinos_precondition.h.

## Member Function Documentation

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

Initialize function. Takes the matrix which is used to form the preconditioner, and additional flags if there are any.

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