Reference documentation for deal.II version Git d234d5a459 2020-07-13 15:04:13 -0400
PETScWrappers::PreconditionBlockJacobi Class Reference

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

Inheritance diagram for PETScWrappers::PreconditionBlockJacobi:
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## Public Member Functions

PreconditionBlockJacobi ()=default

Public Member Functions inherited from PETScWrappers::PreconditionerBase
PreconditionerBase ()

virtual ~PreconditionerBase ()

void clear ()

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

void Tvmult (VectorBase &dst, const VectorBase &src) const

const PC & get_pc () const

## Protected Member Functions

void initialize ()

Protected Member Functions inherited from PETScWrappers::PreconditionerBase
void create_pc ()

operator Mat () const

## Protected Attributes

Protected Attributes inherited from PETScWrappers::PreconditionerBase
PC pc

Mat matrix

## Detailed Description

A class that implements the interface to use the PETSc Block Jacobi preconditioner. PETSc defines the term "block Jacobi" as a preconditioner in which it looks at a number of diagonal blocks of the matrix and then defines a preconditioner in which the preconditioner matrix has the same block structure as only these diagonal blocks, and each diagonal block of the preconditioner is an approximation of the inverse of the corresponding block of the original matrix. The blocking structure of the matrix is determined by the association of degrees of freedom to the individual processors in an MPI-parallel job. If you use this preconditioner on a sequential job (or an MPI job with only one process) then the entire matrix is the only block.

By default, PETSc uses an ILU(0) decomposition of each diagonal block of the matrix for preconditioning. This can be changed, as is explained in the relevant section of the PETSc manual, but is not implemented here.

See the comment in the base class PreconditionerBase for when this preconditioner may or may not work.

Definition at line 220 of file petsc_precondition.h.

## ◆ PreconditionBlockJacobi() [1/3]

 PETScWrappers::PreconditionBlockJacobi::PreconditionBlockJacobi ( )
default

Empty Constructor. You need to call initialize() before using this object.

## ◆ PreconditionBlockJacobi() [2/3]

 PreconditionBlockJacobi< MatrixType, inverse_type >::PreconditionBlockJacobi ( const MatrixBase & matrix, const AdditionalData & additional_data = AdditionalData() )

Constructor. Take the matrix which is used to form the preconditioner, and additional flags if there are any.

Definition at line 189 of file petsc_precondition.cc.

## ◆ PreconditionBlockJacobi() [3/3]

 PreconditionBlockJacobi< MatrixType, inverse_type >::PreconditionBlockJacobi ( const MPI_Comm communicator, const AdditionalData & additional_data = AdditionalData() )

Same as above but without setting a matrix to form the preconditioner. Intended to be used with SLEPc objects.

Definition at line 175 of file petsc_precondition.cc.

## ◆ initialize() [1/2]

 void PreconditionBlockJacobi< MatrixType, inverse_type >::initialize ( const MatrixBase & matrix, const AdditionalData & additional_data = AdditionalData() )

Initialize the preconditioner object and calculate all data that is necessary for applying it in a solver. This function is automatically called when calling the constructor with the same arguments and is only used if you create the preconditioner without arguments.

Definition at line 208 of file petsc_precondition.cc.

## ◆ initialize() [2/2]

 void PreconditionBlockJacobi< MatrixType, inverse_type >::initialize ( )
protected

Initialize the preconditioner object without knowing a particular matrix. This function sets up appropriate parameters to the underlying PETSc object after it has been created.

Definition at line 197 of file petsc_precondition.cc.