PreconditionIdentity Class Reference

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

Inheritance diagram for PreconditionIdentity:

Classes
struct	AdditionalData

Public Types
typedef types::global_dof_index	size_type

Public Member Functions
	PreconditionIdentity ()
template<typename MatrixType >
void	initialize (const MatrixType &matrix, const AdditionalData &additional_data=AdditionalData())
template<class VectorType >
void	vmult (VectorType &, const VectorType &) const
template<class VectorType >
void	Tvmult (VectorType &, const VectorType &) const
template<class VectorType >
void	vmult_add (VectorType &, const VectorType &) const
template<class VectorType >
void	Tvmult_add (VectorType &, const VectorType &) const
void	clear ()
size_type	m () const
size_type	n () const
Public Member Functions inherited from Subscriptor
	Subscriptor ()
	Subscriptor (const Subscriptor &)
virtual	~Subscriptor ()
Subscriptor &	operator= (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."<< "\"<< "(Additional information: "<< arg3<< ")\"<< "See the entry in the Frequently Asked Questions of "<< "deal.II (linked to from http://www.dealii.org/) for "<< "a lot more information on what this error means and "<< "how to fix programs in which it happens.")
	DeclException2 (ExcNoSubscriber, char *, char *,<< "No subscriber with identifier <"<< arg2<< "> subscribes to this object of class "<< arg1<< ". Consequently, it cannot be unsubscribed.")
template<class Archive >
void	serialize (Archive &ar, const unsigned int version)

Private Attributes
size_type	n_rows
size_type	n_columns

Detailed Description

No preconditioning. This class helps you, if you want to use a linear solver without preconditioning. All solvers in LAC require a preconditioner. Therefore, you must use the identity provided here to avoid preconditioning. It can be used in the following way:

SolverControl           solver_control (1000, 1e-12);
SolverCG<>              cg (solver_control);
cg.solve (system_matrix, solution, system_rhs,
         PreconditionIdentity());

See the step-3 tutorial program for an example and additional explanations.

Alternatively, the IdentityMatrix class can be used to precondition in this way.

Author

Guido Kanschat, 1999; extension for full compatibility with LinearOperator class: Jean-Paul Pelteret, 2015

Definition at line 72 of file precondition.h.

Member Typedef Documentation

size_type

typedef types::global_dof_index PreconditionIdentity::size_type

Declare type for container size.

Definition at line 78 of file precondition.h.

Constructor & Destructor Documentation

PreconditionIdentity()

PreconditionIdentity::PreconditionIdentity

(

)

Constructor, sets the domain and range sizes to their defaults.

Member Function Documentation

initialize()

template<typename MatrixType >

void PreconditionIdentity::initialize	(	const MatrixType &	matrix,
		const AdditionalData &	additional_data = AdditionalData()
	)

The matrix argument is ignored and here just for compatibility with more complex preconditioners.

vmult()

template<class VectorType >

void PreconditionIdentity::vmult	(	VectorType &	,
		const VectorType &
	)		const

Apply preconditioner.

Tvmult()

template<class VectorType >

void PreconditionIdentity::Tvmult	(	VectorType &	,
		const VectorType &
	)		const

Apply transpose preconditioner. Since this is the identity, this function is the same as vmult().

vmult_add()

template<class VectorType >

void PreconditionIdentity::vmult_add	(	VectorType &	,
		const VectorType &
	)		const

Apply preconditioner, adding to the previous value.

Tvmult_add()

template<class VectorType >

void PreconditionIdentity::Tvmult_add	(	VectorType &	,
		const VectorType &
	)		const

Apply transpose preconditioner, adding. Since this is the identity, this function is the same as vmult_add().

clear()

void PreconditionIdentity::clear ( )

inline

This function is only present to provide the interface of a preconditioner to be handed to a smoother. This does nothing.

Definition at line 135 of file precondition.h.

m()

size_type PreconditionIdentity::m

(

)

const

Return the dimension of the codomain (or range) space. To remember: the matrix is of dimension .

Note

This function should only be called if the preconditioner has been initialized.

n()

size_type PreconditionIdentity::n

(

)

const

Return the dimension of the domain space. To remember: the matrix is of dimension .

Note

This function should only be called if the preconditioner has been initialized.

Member Data Documentation

n_rows

size_type PreconditionIdentity::n_rows

private

The dimension of the range space.

Definition at line 159 of file precondition.h.

n_columns

size_type PreconditionIdentity::n_columns

private

The dimension of the domain space.

Definition at line 164 of file precondition.h.

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

• deal.II/lac/precondition.h