BlockInfo Class Reference

A small class collecting the different BlockIndices involved in global, multilevel and local computations. More...

#include <deal.II/dofs/block_info.h>

Inheritance diagram for BlockInfo:

Public Member Functions
template<int dim, int spacedim>
void	initialize (const DoFHandler< dim, spacedim > &, bool levels_only=false, bool active_only=false)
	Fill the object with values describing block structure of the DoFHandler. More...
template<int dim, int spacedim>
void	initialize_local (const DoFHandler< dim, spacedim > &)
	Initialize block structure on cells and compute renumbering between cell dofs and block cell dofs.
const BlockIndices &	global () const
const BlockIndices &	local () const
const BlockIndices &	level (unsigned int level) const
types::global_dof_index	renumber (const unsigned int i) const
unsigned int	n_base_elements () const
unsigned int	base_element (const unsigned int i) const
template<class OS >
void	print (OS &stream) const
std::size_t	memory_consumption () const
template<class Archive >
void	serialize (Archive &ar, const unsigned int)
Public Member Functions inherited from Subscriptor
	Subscriptor ()
	Subscriptor (const Subscriptor &)
	Subscriptor (Subscriptor &&) noexcept
virtual	~Subscriptor ()
Subscriptor &	operator= (const Subscriptor &)
Subscriptor &	operator= (Subscriptor &&) noexcept
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
BlockIndices	bi_global
	The block structure of the global system.
std::vector< BlockIndices >	levels
	The multilevel block structure.
BlockIndices	bi_local
	The block structure of the cell systems.
std::vector< unsigned int >	base_elements
std::vector< types::global_dof_index >	local_renumbering

Additional Inherited Members
Static Public Member Functions inherited from Subscriptor
static ::ExceptionBase &	ExcInUse (int arg1, std::string arg2, std::string arg3)
static ::ExceptionBase &	ExcNoSubscriber (std::string arg1, std::string arg2)

Detailed Description

A small class collecting the different BlockIndices involved in global, multilevel and local computations.

Once a DoFHandler has been initialized with an FESystem, a data object of type BlockInfo (accessed by DoFHandler::block_info() ) is filled, which reflects the block structure of the degrees of freedom.

BlockInfo consists of several BlockIndices objects. The member global() reflects the block structure of the system on the active cell level, usually referred to as the global system. As soon as DoFHandler::distribute_dofs() has been called, the function BlockIndices::block_size() in global() will return the correct sizes of each block. After DoFRenumbering::block_wise(), BlockIndices::block_start() will return the start index for each of the blocks.

When a DoFHandler with levels is used, the same structure is automatically generated for each level. The level blocks can be accessed through level().

Finally, there are local() BlockIndices, which describe the block structure on a single cell. This is used for instance by MeshWorker::Assembler::MatrixLocalBlocksToGlobalBlocks. The local indices are not filled automatically, since they change the behavior of the MeshWorker::Assembler classes relying on BlockInfo. They must be initialized by hand through initialize_local().

Usage

The most common usage for this object is initializing vectors as in the following code:

DoFHandler<dim> dof_handler(triangulation);
dof_handler.distribute_dofs(fe_system);
dof_handler.distribute_mg_dofs(fe_system);
DoFRenumbering::block_wise(dof_handler);

BlockVector<double> solution(dof_handler.block_info().global());

MGLevelObject<BlockVector<double> > mg_vector(0, triangulation.n_levels()-1);
for (unsigned int i = 0; i < triangulation.n_levels(); ++i)
  {
    mg_vector[i].reinit(dof_handler.block_info().level(i));
  }

In this example, solution obtains the block structure needed to represent a finite element function on the DoFHandler. Similarly, all levels of mg_vector will have the block structure needed on that level.

Todo:

Extend the functions local() and renumber() to the concept to hp::DoFHandler.

Author

Guido Kanschat, 2009

Definition at line 93 of file block_info.h.

Member Function Documentation

initialize()

template<int dim, int spacedim>

void BlockInfo::initialize	(	const DoFHandler< dim, spacedim > &	dof,
		bool	levels_only = false,
		bool	active_only = false
	)

Fill the object with values describing block structure of the DoFHandler.

By default, this function will attempt to initialize whatever is possible. If active dofs have been assigned int the DoFHandler argument, they BlockIndices for those will be generated. The same for level dofs.

This default behavior can be overridden by the two parameters, which can switch off active dofs or level dofs.

This function will also clear the local() indices.

Definition at line 28 of file block_info.cc.

global()

const BlockIndices & BlockInfo::global ( ) const

inline

Access the BlockIndices structure of the global system.

Definition at line 209 of file block_info.h.

local()

const BlockIndices & BlockInfo::local ( ) const

inline

Access BlockIndices for the local system on a cell.

Definition at line 217 of file block_info.h.

level()

const BlockIndices & BlockInfo::level ( unsigned int  level ) const

inline

Access the BlockIndices structure of a level in the multilevel hierarchy.

Definition at line 225 of file block_info.h.

renumber()

types::global_dof_index BlockInfo::renumber ( const unsigned int  i ) const

inline

Return the index after local renumbering.

The input of this function is an index between zero and the number of dofs per cell, numbered in local block ordering, that is first all indices of the first system block, then all of the second block and so forth. The function then outputs the index in the standard local numbering of DoFAccessor.

Definition at line 233 of file block_info.h.

n_base_elements()

unsigned int BlockInfo::n_base_elements ( ) const

inline

The number of base elements.

Definition at line 252 of file block_info.h.

base_element()

unsigned int BlockInfo::base_element ( const unsigned int  i ) const

inline

Return the base element of this index.

Definition at line 242 of file block_info.h.

print()

template<class OS >

void BlockInfo::print ( OS &  stream ) const

inline

Write a summary of the block structure to the stream.

Definition at line 262 of file block_info.h.

memory_consumption()

std::size_t BlockInfo::memory_consumption ( ) const

inline

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

Definition at line 293 of file block_info.h.

serialize()

template<class Archive >

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

Read or write the data of this object to or from a stream for the purpose of serialization

Definition at line 303 of file block_info.h.

Member Data Documentation

base_elements

std::vector<unsigned int> BlockInfo::base_elements

private

The base element associated with each block.

Definition at line 194 of file block_info.h.

local_renumbering

std::vector<types::global_dof_index> BlockInfo::local_renumbering

private

A vector containing the renumbering from the standard order of degrees of freedom on a cell to a component wise ordering. Filled by initialize().

Definition at line 200 of file block_info.h.

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

• deal.II/dofs/block_info.h
• source/dofs/block_info.cc