Reference documentation for deal.II version Git ac854ef673 2021-03-06 10:09:45 +0100
DiagonalMatrix< VectorType > Class Template Reference

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

Inheritance diagram for DiagonalMatrix< VectorType >:
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## Public Types

using value_type = typename VectorType::value_type

using size_type = typename VectorType::size_type

## Public Member Functions

DiagonalMatrix ()=default

DiagonalMatrix (const VectorType &vec)

void reinit (const VectorType &vec)

void compress (VectorOperation::values operation)

VectorTypeget_vector ()

void clear ()

const VectorTypeget_vector () const

size_type m () const

size_type n () const

value_type operator() (const size_type i, const size_type j) const

value_typeoperator() (const size_type i, const size_type j)

template<typename number2 >
void add (const size_type row, const size_type n_cols, const size_type *col_indices, const number2 *values, const bool elide_zero_values=true, const bool col_indices_are_sorted=false)

void add (const size_type i, const size_type j, const value_type value)

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

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

void vmult_add (VectorType &dst, const VectorType &src) const

void Tvmult_add (VectorType &dst, const VectorType &src) const

void initialize_dof_vector (VectorType &dst) const

std::size_t memory_consumption () 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)

## Private Attributes

VectorType diagonal

## Detailed Description

### template<typename VectorType = Vector<double>> class DiagonalMatrix< VectorType >

This class represents a n x n diagonal matrix based on a vector of size n. The matrix-vector products are realized by VectorType::scale, so the template vector class needs to provide a scale() method.

When using this class with ConstraintsMatrix::distribute_local_to_global(), the underlying vector needs to provide write access to all entries referenced by cells in an assembly process. This means that this class also needs access to ghost entries that are owned by other processors than the calling one. In practice this requires initialization of the vector as follows

diagonal_matrix.get_vector();
diagonal_vector.reinit(locally_owned_dofs,
locally_relevant_dofs,
mpi_communicator);

Definition at line 48 of file diagonal_matrix.h.

## ◆ value_type

template<typename VectorType = Vector<double>>
 using DiagonalMatrix< VectorType >::value_type = typename VectorType::value_type

Definition at line 51 of file diagonal_matrix.h.

## ◆ size_type

template<typename VectorType = Vector<double>>
 using DiagonalMatrix< VectorType >::size_type = typename VectorType::size_type

Definition at line 52 of file diagonal_matrix.h.

## ◆ DiagonalMatrix() [1/2]

template<typename VectorType = Vector<double>>
 DiagonalMatrix< VectorType >::DiagonalMatrix ( )
default

Default constructor. The object needs still to be reinitialized to be usable.

## ◆ DiagonalMatrix() [2/2]

template<typename VectorType = Vector<double>>
 DiagonalMatrix< VectorType >::DiagonalMatrix ( const VectorType & vec )
explicit

Constructor initializing this object as a diagonal matrix of size n x n where n is the size of the vector, and with diagonal entries equal to the elements of vec.

## ◆ reinit()

template<typename VectorType = Vector<double>>
 void DiagonalMatrix< VectorType >::reinit ( const VectorType & vec )

Initialize with a given vector by copying the content of the vector vec.

## ◆ compress()

template<typename VectorType = Vector<double>>
 void DiagonalMatrix< VectorType >::compress ( VectorOperation::values operation )

Compresses the data structures and allows the resulting matrix to be used in all other operations like matrix-vector products. This is a collective operation, i.e., it needs to be run on all processors when used in parallel.

## ◆ get_vector() [1/2]

template<typename VectorType = Vector<double>>
 VectorType& DiagonalMatrix< VectorType >::get_vector ( )

Return a reference to the underlying vector for manipulation of the entries on the matrix diagonal.

## ◆ clear()

template<typename VectorType = Vector<double>>
 void DiagonalMatrix< VectorType >::clear ( )

Clear content of this object and reset to the state of default constructor.

## ◆ get_vector() [2/2]

template<typename VectorType = Vector<double>>
 const VectorType& DiagonalMatrix< VectorType >::get_vector ( ) const

Return a read-only reference to the underlying vector.

## ◆ m()

template<typename VectorType = Vector<double>>
 size_type DiagonalMatrix< VectorType >::m ( ) const

Number of rows of this matrix. This number corresponds to the size of the underlying vector.

## ◆ n()

template<typename VectorType = Vector<double>>
 size_type DiagonalMatrix< VectorType >::n ( ) const

Number of columns of this matrix. This number corresponds to the size of the underlying vector.

## ◆ operator()() [1/2]

template<typename VectorType = Vector<double>>
 value_type DiagonalMatrix< VectorType >::operator() ( const size_type i, const size_type j ) const

Read-only access to a value. This is restricted to the case where i==j due to the matrix storage.

If the vector representing the diagonal is distributed with MPI, not all of the indices i might actually be accessible. Refer to the method get_vector().locally_owned_elements() for the entries that actually are accessible.

## ◆ operator()() [2/2]

template<typename VectorType = Vector<double>>
 value_type& DiagonalMatrix< VectorType >::operator() ( const size_type i, const size_type j )

Read-write access to a value. This is restricted to the case where i==j due to the matrix storage.

If the vector representing the diagonal is distributed with MPI, not all of the indices i might actually be accessible. Refer to the method get_vector().locally_owned_elements() for the entries that actually are accessible.

template<typename VectorType = Vector<double>>
template<typename number2 >
 void DiagonalMatrix< VectorType >::add ( const size_type row, const size_type n_cols, const size_type * col_indices, const number2 * values, const bool elide_zero_values = true, const bool col_indices_are_sorted = false )

Add an array of values given by values in the given global matrix row at columns specified by col_indices. Due to the storage of this matrix, entries are only added to the diagonal of the matrix. All other entries are ignored and no exception is thrown.

This function is for a consistent interface with the other matrix classes in deal.II and can be used in AffineConstraints::distribute_local_to_global to get exactly the same diagonal as when assembling into a sparse matrix.

template<typename VectorType = Vector<double>>
 void DiagonalMatrix< VectorType >::add ( const size_type i, const size_type j, const value_type value )

Add value to the element (i,j).

Due to the storage of this matrix, entries are only added to the diagonal of the matrix. All other entries are ignored and no exception is thrown.

## ◆ vmult()

template<typename VectorType = Vector<double>>
 void DiagonalMatrix< VectorType >::vmult ( VectorType & dst, const VectorType & src ) const

Performs a matrix-vector multiplication with the given matrix.

## ◆ Tvmult()

template<typename VectorType = Vector<double>>
 void DiagonalMatrix< VectorType >::Tvmult ( VectorType & dst, const VectorType & src ) const

Performs a transpose matrix-vector multiplication with the given matrix. Since this represents a diagonal matrix, exactly the same as vmult().

template<typename VectorType = Vector<double>>
 void DiagonalMatrix< VectorType >::vmult_add ( VectorType & dst, const VectorType & src ) const

Adds the result of a matrix-vector multiplication into the destination vector dst. Needs to create a temporary vector, which makes performance slower than for vmult().

template<typename VectorType = Vector<double>>
 void DiagonalMatrix< VectorType >::Tvmult_add ( VectorType & dst, const VectorType & src ) const

Adds the result of a transpose matrix-vector multiplication into the destination vector dst. Needs to create a temporary vector, which makes performance slower than for Tvmult().

## ◆ initialize_dof_vector()

template<typename VectorType = Vector<double>>
 void DiagonalMatrix< VectorType >::initialize_dof_vector ( VectorType & dst ) const

Initialize vector dst to have the same size and partition as diagonal member of this class.

This is a part of the interface required by linear_operator().

## ◆ memory_consumption()

template<typename VectorType = Vector<double>>
 std::size_t DiagonalMatrix< VectorType >::memory_consumption ( ) const

Return the memory consumption of this object.

## ◆ 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 136 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 156 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 301 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 318 of file subscriptor.h.

## ◆ list_subscribers() [2/2]

 void Subscriptor::list_subscribers ( ) const
inherited

List the subscribers to deallog.

Definition at line 204 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 310 of file subscriptor.h.

## ◆ diagonal

template<typename VectorType = Vector<double>>
 VectorType DiagonalMatrix< VectorType >::diagonal
private

The stored vector.

Definition at line 219 of file diagonal_matrix.h.

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