Reference documentation for deal.II version Git 6fa7894 2017-12-12 13:14:59 +0100
BlockIndices Class Reference

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

Inheritance diagram for BlockIndices:
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## Public Types

typedef types::global_dof_index size_type

## Public Member Functions

BlockIndices ()

BlockIndices (const std::vector< size_type > &block_sizes)

BlockIndices (BlockIndices &&b)

BlockIndices (const BlockIndices &)=default

BlockIndices (const unsigned int n_blocks, const size_type block_size=0)

void reinit (const unsigned int n_blocks, const size_type n_elements_per_block)

void reinit (const std::vector< size_type > &block_sizes)

void push_back (const size_type size)

BlockIndicesoperator= (const BlockIndices &b)

BlockIndicesoperator= (BlockIndices &&)

bool operator== (const BlockIndices &b) const

void swap (BlockIndices &b)

std::size_t memory_consumption () const

Size information
unsigned int size () const

size_type total_size () const

size_type block_size (const unsigned int i) const

std::string to_string () const

Index conversion

Functions in this group assume an object, which was created after sorting by block, such that each block forms a set of consecutive indices in the object. If applied to other objects, the numbers obtained from these functions are meaningless.

std::pair< unsigned int, size_typeglobal_to_local (const size_type i) const

size_type local_to_global (const unsigned int block, const size_type index) const

size_type block_start (const unsigned int i) const

Public Member Functions inherited from Subscriptor
Subscriptor ()

Subscriptor (const Subscriptor &)

Subscriptor (Subscriptor &&)

virtual ~Subscriptor ()

Subscriptoroperator= (const Subscriptor &)

Subscriptoroperator= (Subscriptor &&)

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

unsigned int n_blocks

std::vector< size_typestart_indices

## Related Functions

(Note that these are not member functions.)

void swap (BlockIndices &u, BlockIndices &v)

Static Public Member Functions inherited from Subscriptor
static::ExceptionBase & ExcInUse (int arg1, char *arg2, std::string &arg3)

static::ExceptionBase & ExcNoSubscriber (char *arg1, char *arg2)

## Detailed Description

BlockIndices represents a range of indices (such as the range $$[0,N)$$ of valid indices for elements of a vector) and how this one range is broken down into smaller but contiguous "blocks" (such as the velocity and pressure parts of a solution vector). In particular, it provides the ability to translate between global indices and the indices within a block. This class is used, for example, in the BlockVector, BlockSparsityPattern, and BlockMatrixBase classes.

The information that can be obtained from this class falls into two groups. First, it is possible to query the global size of the index space (through the total_size() member function), and the number of blocks and their sizes (via size() and the block_size() functions).

Secondly, this class manages the conversion of global indices to the local indices within this block, and the other way around. This is required, for example, when you address a global element in a block vector and want to know within which block this is, and which index within this block it corresponds to. It is also useful if a matrix is composed of several blocks, where you have to translate global row and column indices to local ones.

Block (linear algebra)

Definition at line 57 of file block_indices.h.

## Member Typedef Documentation

Declare the type for container size.

Definition at line 63 of file block_indices.h.

## Constructor & Destructor Documentation

 BlockIndices::BlockIndices ( )
inline

Default constructor. Initialize for zero blocks.

Definition at line 274 of file block_indices.h.

 BlockIndices::BlockIndices ( const std::vector< size_type > & block_sizes )
inline

Constructor. Initialize the number of entries in each block i as block_sizes[i]. The number of blocks will be the size of block_sizes.

Definition at line 296 of file block_indices.h.

 BlockIndices::BlockIndices ( BlockIndices && b )
inline

Move constructor. Initialize a new object by stealing the internal data of another BlockIndices object.

Definition at line 307 of file block_indices.h.

 BlockIndices::BlockIndices ( const BlockIndices & )
default

Copy constructor.

 BlockIndices::BlockIndices ( const unsigned int n_blocks, const size_type block_size = 0 )
inlineexplicit

Specialized constructor for a structure with blocks of equal size.

Definition at line 283 of file block_indices.h.

## Member Function Documentation

 void BlockIndices::reinit ( const unsigned int n_blocks, const size_type n_elements_per_block )
inline

Reinitialize the number of blocks and assign each block the same number of elements.

Definition at line 247 of file block_indices.h.

 void BlockIndices::reinit ( const std::vector< size_type > & block_sizes )
inline

Reinitialize the number of indices within each block from the given argument. The number of blocks will be adjusted to the size of block_sizes and the size of block i is set to block_sizes[i].

Definition at line 260 of file block_indices.h.

 void BlockIndices::push_back ( const size_type size )
inline

Add another block of given size to the end of the block structure.

Definition at line 320 of file block_indices.h.

 unsigned int BlockIndices::size ( ) const
inline

Number of blocks in index field.

Definition at line 359 of file block_indices.h.

 BlockIndices::size_type BlockIndices::total_size ( ) const
inline

Return the total number of indices accumulated over all blocks, that is, the dimension of the vector space of the block vector.

Definition at line 368 of file block_indices.h.

 BlockIndices::size_type BlockIndices::block_size ( const unsigned int i ) const
inline

The size of the ith block.

Definition at line 378 of file block_indices.h.

 std::string BlockIndices::to_string ( ) const
inline

String representation of the block sizes. The output is of the form [nb->b1,b2,b3|s], where nb is n_blocks(), s is total_size() and b1 etc. are the values returned by block_size() for each of the blocks.

Definition at line 388 of file block_indices.h.

 std::pair< unsigned int, BlockIndices::size_type > BlockIndices::global_to_local ( const size_type i ) const
inline

Return the block and the index within that block for the global index i. The first element of the pair is the block, the second the index within it.

Definition at line 330 of file block_indices.h.

 BlockIndices::size_type BlockIndices::local_to_global ( const unsigned int block, const size_type index ) const
inline

Return the global index of index in block block.

Definition at line 346 of file block_indices.h.

 BlockIndices::size_type BlockIndices::block_start ( const unsigned int i ) const
inline

The start index of the ith block.

Definition at line 405 of file block_indices.h.

 BlockIndices & BlockIndices::operator= ( const BlockIndices & b )
inline

Copy operator.

Definition at line 415 of file block_indices.h.

 BlockIndices & BlockIndices::operator= ( BlockIndices && b )
inline

Move assignment operator. Move another BlockIndices object onto the current one by transferring its contents.

Definition at line 426 of file block_indices.h.

 bool BlockIndices::operator== ( const BlockIndices & b ) const
inline

Compare whether two objects are the same, i.e. whether the number of blocks and the sizes of all blocks are equal.

Definition at line 441 of file block_indices.h.

 void BlockIndices::swap ( BlockIndices & b )
inline

Swap the contents of these two objects.

Definition at line 457 of file block_indices.h.

 std::size_t BlockIndices::memory_consumption ( ) const
inline

Determine an estimate for the memory consumption (in bytes) of this object.

Definition at line 467 of file block_indices.h.

## Friends And Related Function Documentation

 void swap ( BlockIndices & u, BlockIndices & v )
related

Global function swap which overloads the default implementation of the C++ standard library which uses a temporary object. The function simply exchanges the data of the two objects.

Definition at line 487 of file block_indices.h.

## Member Data Documentation

 unsigned int BlockIndices::n_blocks
private

Number of blocks. While this value could be obtained through start_indices.size()-1, we cache this value for faster access.

Definition at line 207 of file block_indices.h.

 std::vector BlockIndices::start_indices
private

Global starting index of each vector. The last and redundant value is the total number of entries.

Definition at line 213 of file block_indices.h.

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