Reference documentation for deal.II version 9.6.0
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PreconditionRelaxation< MatrixType, PreconditionerType > Class Template Reference

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

Inheritance diagram for PreconditionRelaxation< MatrixType, PreconditionerType >:

Classes

class  AdditionalData
 

Public Types

using size_type = types::global_dof_index
 
using EigenvalueInformation = internal::EigenvalueInformation
 

Public Member Functions

void initialize (const MatrixType &A, const AdditionalData &parameters=AdditionalData())
 
void clear ()
 
size_type m () const
 
size_type n () const
 
template<typename VectorType >
void vmult (VectorType &, const VectorType &) const
 
template<typename VectorType >
void Tvmult (VectorType &, const VectorType &) const
 
template<typename VectorType >
void step (VectorType &x, const VectorType &rhs) const
 
template<typename VectorType >
void Tstep (VectorType &x, const VectorType &rhs) const
 
template<typename VectorType >
EigenvalueInformation estimate_eigenvalues (const VectorType &src) const
 
double get_relaxation () const
 
template<class Archive >
void serialize (Archive &ar, const unsigned int version)
 
Subscriptor functionality

Classes derived from Subscriptor provide a facility to subscribe to this object. This is mostly used by the SmartPointer 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 ::ExceptionBaseExcInUse (int arg1, std::string arg2, std::string arg3)
 
static ::ExceptionBaseExcNoSubscriber (std::string arg1, std::string arg2)
 

Protected Attributes

SmartPointer< const MatrixType, PreconditionRelaxation< MatrixType > > A
 
AdditionalData data
 
std::shared_ptr< PreconditionerType > preconditioner
 
bool eigenvalues_are_initialized
 

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

std::atomic< unsigned intcounter
 
std::map< std::string, unsigned intcounter_map
 
std::vector< std::atomic< bool > * > validity_pointers
 
const std::type_info * object_info
 

Static Private Attributes

static std::mutex mutex
 

Detailed Description

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
class PreconditionRelaxation< MatrixType, PreconditionerType >

Base class for other preconditioners. Here, only some common features Jacobi, SOR and SSOR preconditioners are implemented. For preconditioning, refer to derived classes.

One iteration is given as:

\[ x^{n+1} = x^{n} + \alpha P^{-1} (b-Ax^n). \]

The relaxation parameter \(\alpha\) has to be in the range:

\[ 0 < \alpha < \frac{2}{\lambda_{\max}(P^{-1}A)}. \]

Its theoretically optimal value is given by:

\[ \alpha := \frac{2}{\lambda_{\min}(P^{-1}A)+\lambda_{\max}(P^{-1}A)}. \]

For details on the algorithm, see [205].

The relaxation parameter can be set manually or can be automatically determined, for which we use the theoretically optimal value. For this purpose, the user needs to set the relaxation parameter to zero. Internally, the minimum and maximum eigenvalues of the preconditioned system are estimated by an eigenvalue algorithm, and the resulting estimate is multiplied by the 1.2 for safety reasons. For more details on the underlying algorithms, see PreconditionChebyshev.

Definition at line 566 of file precondition.h.

Member Typedef Documentation

◆ size_type

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
using PreconditionRelaxation< MatrixType, PreconditionerType >::size_type = types::global_dof_index

Declare type for container size.

Definition at line 572 of file precondition.h.

◆ EigenvalueInformation

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
using PreconditionRelaxation< MatrixType, PreconditionerType >::EigenvalueInformation = internal::EigenvalueInformation

Definition at line 665 of file precondition.h.

◆ map_value_type

using Subscriptor::map_value_type = decltype(counter_map)::value_type
privateinherited

The data type used in counter_map.

Definition at line 229 of file subscriptor.h.

◆ map_iterator

using Subscriptor::map_iterator = decltype(counter_map)::iterator
privateinherited

The iterator type used in counter_map.

Definition at line 234 of file subscriptor.h.

Member Function Documentation

◆ initialize()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
void PreconditionRelaxation< MatrixType, PreconditionerType >::initialize ( const MatrixType & A,
const AdditionalData & parameters = AdditionalData() )

Initialize matrix and relaxation parameter. The matrix is just stored in the preconditioner object. The relaxation parameter should be larger than zero and smaller than 2 for numerical reasons. It defaults to 1.

◆ clear()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
void PreconditionRelaxation< MatrixType, PreconditionerType >::clear ( )

Release the matrix and reset its pointer.

◆ m()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
size_type PreconditionRelaxation< MatrixType, PreconditionerType >::m ( ) const

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

◆ n()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
size_type PreconditionRelaxation< MatrixType, PreconditionerType >::n ( ) const

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

◆ vmult()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
template<typename VectorType >
void PreconditionRelaxation< MatrixType, PreconditionerType >::vmult ( VectorType & ,
const VectorType &  ) const

Apply preconditioner.

◆ Tvmult()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
template<typename VectorType >
void PreconditionRelaxation< MatrixType, PreconditionerType >::Tvmult ( VectorType & ,
const VectorType &  ) const

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

◆ step()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
template<typename VectorType >
void PreconditionRelaxation< MatrixType, PreconditionerType >::step ( VectorType & x,
const VectorType & rhs ) const

Perform one step of the preconditioned Richardson iteration

◆ Tstep()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
template<typename VectorType >
void PreconditionRelaxation< MatrixType, PreconditionerType >::Tstep ( VectorType & x,
const VectorType & rhs ) const

Perform one transposed step of the preconditioned Richardson iteration.

◆ estimate_eigenvalues()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
template<typename VectorType >
EigenvalueInformation PreconditionRelaxation< MatrixType, PreconditionerType >::estimate_eigenvalues ( const VectorType & src) const

Estimate eigenvalues and set relaxation parameter.

◆ get_relaxation()

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
double PreconditionRelaxation< MatrixType, PreconditionerType >::get_relaxation ( ) const

Return the relaxation parameter. This function also allows to return the parameter in case it was internally determined by running an eigenvalue algorithm.

◆ subscribe()

void Subscriptor::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 135 of file subscriptor.cc.

◆ unsubscribe()

void Subscriptor::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 155 of file subscriptor.cc.

◆ n_subscriptions()

unsigned int Subscriptor::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 300 of file subscriptor.h.

◆ list_subscribers() [1/2]

template<typename StreamType >
void Subscriptor::list_subscribers ( StreamType & stream) const
inlineinherited

List the subscribers to the input stream.

Definition at line 317 of file subscriptor.h.

◆ list_subscribers() [2/2]

void Subscriptor::list_subscribers ( ) const
inherited

List the subscribers to deallog.

Definition at line 203 of file subscriptor.cc.

◆ serialize()

template<class Archive >
void Subscriptor::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 309 of file subscriptor.h.

◆ check_no_subscribers()

void Subscriptor::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 52 of file subscriptor.cc.

Member Data Documentation

◆ A

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
SmartPointer<const MatrixType, PreconditionRelaxation<MatrixType> > PreconditionRelaxation< MatrixType, PreconditionerType >::A
protected

Pointer to the matrix object.

Definition at line 686 of file precondition.h.

◆ data

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
AdditionalData PreconditionRelaxation< MatrixType, PreconditionerType >::data
protected

Stores the additional data passed to the initialize function, obtained through a copy operation.

Definition at line 692 of file precondition.h.

◆ preconditioner

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
std::shared_ptr<PreconditionerType> PreconditionRelaxation< MatrixType, PreconditionerType >::preconditioner
protected

Preconditioner.

Definition at line 697 of file precondition.h.

◆ eigenvalues_are_initialized

template<typename MatrixType = SparseMatrix<double>, typename PreconditionerType = IdentityMatrix>
bool PreconditionRelaxation< MatrixType, PreconditionerType >::eigenvalues_are_initialized
protected

Stores whether the preconditioner has been set up and eigenvalues have been computed.

Definition at line 703 of file precondition.h.

◆ counter

std::atomic<unsigned int> Subscriptor::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 218 of file subscriptor.h.

◆ counter_map

std::map<std::string, unsigned int> Subscriptor::counter_map
mutableprivateinherited

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

Definition at line 224 of file subscriptor.h.

◆ validity_pointers

std::vector<std::atomic<bool> *> Subscriptor::validity_pointers
mutableprivateinherited

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

Definition at line 240 of file subscriptor.h.

◆ object_info

const std::type_info* Subscriptor::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 248 of file subscriptor.h.

◆ mutex

std::mutex Subscriptor::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 271 of file subscriptor.h.


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