Reference documentation for deal.II version Git bedfa10003 2019-09-17 13:28:06 -0600
Public Types | Public Member Functions | Private Attributes | Related Functions | List of all members

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

Inheritance diagram for BlockIndices:

Public Types

using size_type = types::global_dof_index

Public Member Functions

 BlockIndices ()
 BlockIndices (const std::vector< size_type > &block_sizes)
 BlockIndices (BlockIndices &&b) noexcept
 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 &&) noexcept
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 &&) noexcept
virtual ~Subscriptor ()
Subscriptoroperator= (const Subscriptor &)
Subscriptoroperator= (Subscriptor &&) noexcept
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
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)

Additional Inherited Members

- Static Public Member Functions inherited from Subscriptor
static ::ExceptionBaseExcInUse (int arg1, std::string arg2, std::string arg3)
static ::ExceptionBaseExcNoSubscriber (std::string arg1, std::string 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.

See also
Block (linear algebra)
Wolfgang Bangerth, Guido Kanschat, 2000, 2007, 2011

Definition at line 60 of file block_indices.h.

Member Typedef Documentation

◆ size_type

Declare the type for container size.

Definition at line 66 of file block_indices.h.

Constructor & Destructor Documentation

◆ BlockIndices() [1/5]

BlockIndices::BlockIndices ( )

Default constructor. Initialize for zero blocks.

Definition at line 284 of file block_indices.h.

◆ BlockIndices() [2/5]

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

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 302 of file block_indices.h.

◆ BlockIndices() [3/5]

BlockIndices::BlockIndices ( BlockIndices &&  b)

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

Definition at line 311 of file block_indices.h.

◆ BlockIndices() [4/5]

BlockIndices::BlockIndices ( const BlockIndices )

Copy constructor.

◆ BlockIndices() [5/5]

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

Specialized constructor for a structure with blocks of equal size.

Definition at line 291 of file block_indices.h.

Member Function Documentation

◆ reinit() [1/2]

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

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

Definition at line 260 of file block_indices.h.

◆ reinit() [2/2]

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

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 271 of file block_indices.h.

◆ push_back()

void BlockIndices::push_back ( const size_type  size)

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

Definition at line 322 of file block_indices.h.

◆ size()

unsigned int BlockIndices::size ( ) const

Number of blocks in index field.

Definition at line 358 of file block_indices.h.

◆ total_size()

BlockIndices::size_type BlockIndices::total_size ( ) const

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 366 of file block_indices.h.

◆ block_size()

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

The size of the ith block.

Definition at line 376 of file block_indices.h.

◆ to_string()

std::string BlockIndices::to_string ( ) const

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 385 of file block_indices.h.

◆ global_to_local()

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

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 331 of file block_indices.h.

◆ local_to_global()

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

Return the global index of index in block block.

Definition at line 345 of file block_indices.h.

◆ block_start()

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

The start index of the ith block.

Definition at line 401 of file block_indices.h.

◆ operator=() [1/2]

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

Copy operator.

Definition at line 410 of file block_indices.h.

◆ operator=() [2/2]

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

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

Definition at line 420 of file block_indices.h.

◆ operator==()

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

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 434 of file block_indices.h.

◆ swap()

void BlockIndices::swap ( BlockIndices b)

Swap the contents of these two objects.

Definition at line 449 of file block_indices.h.

◆ memory_consumption()

std::size_t BlockIndices::memory_consumption ( ) const

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

Definition at line 458 of file block_indices.h.

Friends And Related Function Documentation

◆ swap()

void swap ( BlockIndices u,
BlockIndices v 

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.

Wolfgang Bangerth, 2000

Definition at line 477 of file block_indices.h.

Member Data Documentation

◆ n_blocks

unsigned int BlockIndices::n_blocks

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

Definition at line 222 of file block_indices.h.

◆ start_indices

std::vector<size_type> BlockIndices::start_indices

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

Definition at line 228 of file block_indices.h.

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