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 &)
	Subscriptor (Subscriptor &&) noexcept
virtual	~Subscriptor ()
Subscriptor &	operator= (const Subscriptor &)
Subscriptor &	operator= (Subscriptor &&) noexcept
void	subscribe (const char *identifier=nullptr) const
void	unsubscribe (const char *identifier=nullptr) const
unsigned int	n_subscriptions () const
void	list_subscribers () const
template<class Archive >
void	serialize (Archive &ar, const unsigned int version)

Private Attributes
size_type	n_rows
size_type	n_columns

Additional Inherited Members
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)

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 73 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 79 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 136 of file precondition.h.

m()

size_type PreconditionIdentity::m

(

)

const

Return the dimension of the codomain (or range) space. Note that the matrix is of dimension \(m \times n\).

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. Note that the matrix is of dimension \(m \times n\).

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 160 of file precondition.h.

n_columns

size_type PreconditionIdentity::n_columns

private

The dimension of the domain space.

Definition at line 165 of file precondition.h.

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

• deal.II/lac/precondition.h