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

Inheritance diagram for PreconditionIdentity:

Classes
struct	AdditionalData

Public Types
using	size_type = types::global_dof_index

Public Member Functions
	PreconditionIdentity ()

template<typename MatrixType >
void	initialize (const MatrixType &matrix, const AdditionalData &additional_data=AdditionalData())

template<typename VectorType >
void	vmult (VectorType &, const VectorType &) const

template<typename VectorType >
void	Tvmult (VectorType &, const VectorType &) const

template<typename VectorType >
void	vmult_add (VectorType &, const VectorType &) const

template<typename VectorType >
void	Tvmult_add (VectorType &, const VectorType &) const

void	clear ()

size_type	m () const

size_type	n () const

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

EnableObserverPointer functionality
Classes derived from EnableObserverPointer provide a facility to subscribe to this object. This is mostly used by the ObserverPointer class.
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

Static Public Member Functions
static ::ExceptionBase &	ExcInUse (int arg1, std::string arg2, std::string arg3)

static ::ExceptionBase &	ExcNoSubscriber (std::string arg1, std::string arg2)

Private Types
using	map_value_type = decltype(counter_map)::value_type

using	map_iterator = decltype(counter_map)::iterator

Private Member Functions
void	check_no_subscribers () const noexcept

Private Attributes
size_type	n_rows

size_type	n_columns

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

Static Private Attributes
static std::mutex	mutex

Detailed Description

This preconditioner implements the identity operator. This class can be used you if you want to use a linear solver without preconditioning, because all linear solvers require the usage of a preconditioner.

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.

Definition at line 218 of file precondition.h.

Member Typedef Documentation

◆ size_type

using PreconditionIdentity::size_type = types::global_dof_index

Declare type for container size.

Definition at line 224 of file precondition.h.

◆ map_value_type

using EnableObserverPointer::map_value_type = decltype(counter_map)::value_type

privateinherited

The data type used in counter_map.

Definition at line 238 of file enable_observer_pointer.h.

◆ map_iterator

using EnableObserverPointer::map_iterator = decltype(counter_map)::iterator

privateinherited

The iterator type used in counter_map.

Definition at line 243 of file enable_observer_pointer.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<typename VectorType >

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

Apply preconditioner.

◆ Tvmult()

template<typename 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<typename VectorType >

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

Apply preconditioner, adding to the previous value.

◆ Tvmult_add()

template<typename 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 ( )

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

◆ 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.

◆ subscribe()

void EnableObserverPointer::subscribe	(	std::atomic< bool > *const	validity,
		const std::string &	identifier = `""`
	)		const

inherited

Subscribes a user of the object by storing the pointer validity. The subscriber may be identified by text supplied as identifier.

Definition at line 131 of file enable_observer_pointer.cc.

◆ unsubscribe()

void EnableObserverPointer::unsubscribe	(	std::atomic< bool > *const	validity,
		const std::string &	identifier = `""`
	)		const

inherited

Unsubscribes a user from the object.

Note: The identifier and the validity pointer must be the same as the one supplied to subscribe().

Definition at line 151 of file enable_observer_pointer.cc.

◆ n_subscriptions()

unsigned int EnableObserverPointer::n_subscriptions ( ) const

inlineinherited

Return the present number of subscriptions to this object. This allows to use this class for reference counted lifetime determination where the last one to unsubscribe also deletes the object.

Definition at line 322 of file enable_observer_pointer.h.

◆ list_subscribers() [1/2]

template<typename StreamType >

void EnableObserverPointer::list_subscribers ( StreamType & stream ) const

inlineinherited

List the subscribers to the input stream.

Definition at line 339 of file enable_observer_pointer.h.

◆ list_subscribers() [2/2]

void EnableObserverPointer::list_subscribers ( ) const

inherited

List the subscribers to deallog.

Definition at line 199 of file enable_observer_pointer.cc.

◆ serialize()

template<class Archive >

void EnableObserverPointer::serialize	(	Archive &	ar,
		const unsigned int	version
	)

inlineinherited

Read or write the data of this object to or from a stream for the purpose of serialization using the BOOST serialization library.

This function does not actually serialize any of the member variables of this class. The reason is that what this class stores is only who subscribes to this object, but who does so at the time of storing the contents of this object does not necessarily have anything to do with who subscribes to the object when it is restored. Consequently, we do not want to overwrite the subscribers at the time of restoring, and then there is no reason to write the subscribers out in the first place.

Definition at line 331 of file enable_observer_pointer.h.

◆ check_no_subscribers()

void EnableObserverPointer::check_no_subscribers ( ) const

privatenoexceptinherited

Check that there are no objects subscribing to this object. If this check passes then it is safe to destroy the current object. It this check fails then this function will either abort or print an error message to deallog (by using the AssertNothrow mechanism), but will not throw an exception.

Note: Since this function is just a consistency check it does nothing in release mode.; If this function is called when there is an uncaught exception then, rather than aborting, this function prints an error message to the standard error stream and returns.

Definition at line 53 of file enable_observer_pointer.cc.

Member Data Documentation

◆ n_rows

size_type PreconditionIdentity::n_rows

private

The dimension of the range space.

Definition at line 313 of file precondition.h.

◆ n_columns

size_type PreconditionIdentity::n_columns

private

The dimension of the domain space.

Definition at line 318 of file precondition.h.

◆ counter

std::atomic<unsigned int> EnableObserverPointer::counter

mutableprivateinherited

Store the number of objects which subscribed to this object. Initially, this number is zero, and upon destruction it shall be zero again (i.e. all objects which subscribed should have unsubscribed again).

The creator (and owner) of an object is counted in the map below if HE manages to supply identification.

We use the mutable keyword in order to allow subscription to constant objects also.

This counter may be read from and written to concurrently in multithreaded code: hence we use the std::atomic class template.

Definition at line 227 of file enable_observer_pointer.h.

◆ counter_map

std::map<std::string, unsigned int> EnableObserverPointer::counter_map

mutableprivateinherited

In this map, we count subscriptions for each different identification string supplied to subscribe().

Definition at line 233 of file enable_observer_pointer.h.

◆ validity_pointers

std::vector<std::atomic<bool> *> EnableObserverPointer::validity_pointers

mutableprivateinherited

In this vector, we store pointers to the validity bool in the ObserverPointer objects that subscribe to this class.

Definition at line 249 of file enable_observer_pointer.h.

◆ object_info

const std::type_info* EnableObserverPointer::object_info

mutableprivateinherited

Pointer to the typeinfo object of this object, from which we can later deduce the class name. Since this information on the derived class is neither available in the destructor, nor in the constructor, we obtain it in between and store it here.

Definition at line 257 of file enable_observer_pointer.h.

◆ mutex

std::mutex EnableObserverPointer::mutex

staticprivateinherited

A mutex used to ensure data consistency when accessing the mutable members of this class. This lock is used in the subscribe() and unsubscribe() functions, as well as in list_subscribers().

Definition at line 280 of file enable_observer_pointer.h.

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

include/deal.II/lac/precondition.h

Classes

Public Types

Public Member Functions

Static Public Member Functions

Private Types

Private Member Functions

Private Attributes

Static Private Attributes

Detailed Description

Member Typedef Documentation

◆ size_type

◆ map_value_type

◆ map_iterator

Constructor & Destructor Documentation

◆ PreconditionIdentity()

Member Function Documentation

◆ initialize()

◆ vmult()

◆ Tvmult()

◆ vmult_add()

◆ Tvmult_add()

◆ clear()

◆ m()

◆ n()

◆ subscribe()

◆ unsubscribe()

◆ n_subscriptions()

◆ list_subscribers() [1/2]

◆ list_subscribers() [2/2]

◆ serialize()

◆ check_no_subscribers()

Member Data Documentation

◆ n_rows

◆ n_columns

◆ counter

◆ counter_map

◆ validity_pointers

◆ object_info

◆ mutex