Reference documentation for deal.II version 8.4.1
parallel::distributed::BlockVector< Number > Class Template Reference

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

Inheritance diagram for parallel::distributed::BlockVector< Number >:
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## Public Types

typedef BlockVectorBase< Vector< Number > > BaseClass

typedef BaseClass::BlockType BlockType

typedef BaseClass::value_type value_type

Public Types inherited from BlockVectorBase< Vector< Number > >
typedef Vector< Number > BlockType

typedef BlockType::real_type real_type

## Public Member Functions

BlockVector (const size_type num_blocks=0, const size_type block_size=0)

BlockVector (const BlockVector< Number > &V)

template<typename OtherNumber >
BlockVector (const BlockVector< OtherNumber > &v)

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

BlockVector (const std::vector< IndexSet > &local_ranges, const std::vector< IndexSet > &ghost_indices, const MPI_Comm communicator)

BlockVector (const std::vector< IndexSet > &local_ranges, const MPI_Comm communicator)

~BlockVector ()

BlockVectoroperator= (const value_type s)

BlockVectoroperator= (const BlockVector &V)

template<class Number2 >
BlockVectoroperator= (const BlockVector< Number2 > &V)

BlockVectoroperator= (const Vector< Number > &V)

BlockVector< Number > & operator= (const PETScWrappers::MPI::BlockVector &petsc_vec)

BlockVector< Number > & operator= (const TrilinosWrappers::MPI::BlockVector &trilinos_vec)

void reinit (const size_type num_blocks, const size_type block_size=0, const bool omit_zeroing_entries=false)

void reinit (const std::vector< size_type > &N, const bool omit_zeroing_entries=false)

template<typename Number2 >
void reinit (const BlockVector< Number2 > &V, const bool omit_zeroing_entries=false)

void compress (::VectorOperation::values operation)

void update_ghost_values () const

void zero_out_ghosts ()

bool has_ghost_elements () const

bool all_zero () const

bool is_non_negative () const

template<typename Number2 >
bool operator== (const BlockVector< Number2 > &v) const

template<typename Number2 >
bool operator!= (const BlockVector< Number2 > &v) const

template<typename Number2 >
Number operator* (const BlockVector< Number2 > &V) const

real_type norm_sqr () const

Number mean_value () const

real_type l1_norm () const

real_type l2_norm () const

real_type lp_norm (const real_type p) const

real_type linfty_norm () const

Number add_and_dot (const Number a, const BlockVector< Number > &V, const BlockVector< Number > &W)

template<class BlockVector2 >
void scale (const BlockVector2 &v)

void swap (BlockVector< Number > &v)

DeclException0 (ExcIteratorRangeDoesNotMatchVectorSize)

Public Member Functions inherited from BlockVectorBase< Vector< Number > >
BlockVectorBase ()

void collect_sizes ()

void compress (::VectorOperation::values operation)

BlockTypeblock (const unsigned int i)

const BlockTypeblock (const unsigned int i) const

const BlockIndicesget_block_indices () const

unsigned int n_blocks () const

std::size_t size () const

IndexSet locally_owned_elements () const

iterator begin ()

const_iterator begin () const

iterator end ()

const_iterator end () const

value_type operator() (const size_type i) const

reference operator() (const size_type i)

value_type operator[] (const size_type i) const

reference operator[] (const size_type i)

void extract_subvector_to (const std::vector< size_type > &indices, std::vector< OtherNumber > &values) const

void extract_subvector_to (ForwardIterator indices_begin, const ForwardIterator indices_end, OutputIterator values_begin) const

BlockVectorBaseoperator= (const value_type s)

BlockVectorBaseoperator= (const BlockVectorBase &V)

BlockVectorBaseoperator= (const BlockVectorBase< VectorType2 > &V)

BlockVectorBaseoperator= (const Vector< Number > &v)

bool operator== (const BlockVectorBase< VectorType2 > &v) const

value_type operator* (const BlockVectorBase &V) const

real_type norm_sqr () const

value_type mean_value () const

real_type l1_norm () const

real_type l2_norm () const

real_type linfty_norm () const

value_type add_and_dot (const value_type a, const BlockVectorBase &V, const BlockVectorBase &W)

bool in_local_range (const size_type global_index) const

bool all_zero () const

bool is_non_negative () const

BlockVectorBaseoperator+= (const BlockVectorBase &V)

BlockVectorBaseoperator-= (const BlockVectorBase &V)

void add (const std::vector< size_type > &indices, const std::vector< Number > &values)

void add (const std::vector< size_type > &indices, const Vector< Number > &values)

void add (const size_type n_elements, const size_type *indices, const Number *values)

void add (const BlockVectorBase &V) DEAL_II_DEPRECATED

void add (const value_type a, const BlockVectorBase &V)

void add (const value_type a, const BlockVectorBase &V, const value_type b, const BlockVectorBase &W)

void sadd (const value_type s, const BlockVectorBase &V)

void sadd (const value_type s, const value_type a, const BlockVectorBase &V)

void sadd (const value_type s, const value_type a, const BlockVectorBase &V, const value_type b, const BlockVectorBase &W)

void sadd (const value_type s, const value_type a, const BlockVectorBase &V, const value_type b, const BlockVectorBase &W, const value_type c, const BlockVectorBase &X)

BlockVectorBaseoperator*= (const value_type factor)

BlockVectorBaseoperator/= (const value_type factor)

void scale (const BlockVector2 &v)

void equ (const value_type a, const BlockVector2 &V)

void equ (const value_type a, const BlockVectorBase &V, const value_type b, const BlockVectorBase &W)

void update_ghost_values () const

std::size_t memory_consumption () const

Public Member Functions inherited from Subscriptor
Subscriptor ()

Subscriptor (const Subscriptor &)

virtual ~Subscriptor ()

Subscriptoroperator= (const Subscriptor &)

void subscribe (const char *identifier=0) const

void unsubscribe (const char *identifier=0) const

unsigned int n_subscriptions () const

void list_subscribers () const

DeclException3 (ExcInUse, int, char *, std::string &,<< "Object of class "<< arg2<< " is still used by "<< arg1<< " other objects."<< "\n\n"<< "(Additional information: "<< arg3<< ")\n\n"<< "See the entry in the Frequently Asked Questions of "<< "deal.II (linked to from http://www.dealii.org/) for "<< "a lot more information on what this error means and "<< "how to fix programs in which it happens.")

DeclException2 (ExcNoSubscriber, char *, char *,<< "No subscriber with identifier <"<< arg2<< "> subscribes to this object of class "<< arg1<< ". Consequently, it cannot be unsubscribed.")

template<class Archive >
void serialize (Archive &ar, const unsigned int version)

Static Public Attributes inherited from BlockVectorBase< Vector< Number > >
static const bool supports_distributed_data

Protected Attributes inherited from BlockVectorBase< Vector< Number > >
std::vector< Vector< Number > > components

BlockIndices block_indices

## Detailed Description

### template<typename Number> class parallel::distributed::BlockVector< Number >

An implementation of block vectors based on distributed deal.II vectors. While the base class provides for most of the interface, this class handles the actual allocation of vectors and provides functions that are specific to the underlying vector type.

Note
Instantiations for this template are provided for <float> and <double>; others can be generated in application programs (see the section on Template instantiations in the manual).
Block (linear algebra)

Definition at line 63 of file parallel_block_vector.h.

## Member Typedef Documentation

template<typename Number>
 typedef BlockVectorBase > parallel::distributed::BlockVector< Number >::BaseClass

Definition at line 69 of file parallel_block_vector.h.

template<typename Number>
 typedef BaseClass::BlockType parallel::distributed::BlockVector< Number >::BlockType

Typedef the type of the underlying vector.

Definition at line 74 of file parallel_block_vector.h.

template<typename Number>
 typedef BaseClass::value_type parallel::distributed::BlockVector< Number >::value_type

Import the typedefs from the base class.

Definition at line 79 of file parallel_block_vector.h.

## Constructor & Destructor Documentation

template<typename Number>
 parallel::distributed::BlockVector< Number >::BlockVector ( const size_type num_blocks = 0, const size_type block_size = 0 )
explicit

Constructor. There are three ways to use this constructor. First, without any arguments, it generates an object with no blocks. Given one argument, it initializes num_blocks blocks, but these blocks have size zero. The third variant finally initializes all blocks to the same size block_size.

Confer the other constructor further down if you intend to use blocks of different sizes.

template<typename Number>
 parallel::distributed::BlockVector< Number >::BlockVector ( const BlockVector< Number > & V )

Copy-Constructor. Dimension set to that of V, all components are copied from V

template<typename Number>
template<typename OtherNumber >
 parallel::distributed::BlockVector< Number >::BlockVector ( const BlockVector< OtherNumber > & v )
explicit

Copy constructor taking a BlockVector of another data type. This will fail if there is no conversion path from OtherNumber to Number. Note that you may lose accuracy when copying to a BlockVector with data elements with less accuracy.

Older versions of gcc did not honor the explicit keyword on template constructors. In such cases, it is easy to accidentally write code that can be very inefficient, since the compiler starts performing hidden conversions. To avoid this, this function is disabled if we have detected a broken compiler during configuration.

template<typename Number>
 parallel::distributed::BlockVector< Number >::BlockVector ( const std::vector< size_type > & block_sizes )

Constructor. Set the number of blocks to block_sizes.size() and initialize each block with block_sizes[i] zero elements.

template<typename Number>
 parallel::distributed::BlockVector< Number >::BlockVector ( const std::vector< IndexSet > & local_ranges, const std::vector< IndexSet > & ghost_indices, const MPI_Comm communicator )

Construct a block vector with an IndexSet for the local range and ghost entries for each block.

template<typename Number>
 parallel::distributed::BlockVector< Number >::BlockVector ( const std::vector< IndexSet > & local_ranges, const MPI_Comm communicator )

Same as above but the ghost indices are assumed to be empty.

template<typename Number>
 parallel::distributed::BlockVector< Number >::~BlockVector ( )

Destructor. Clears memory.

## Member Function Documentation

template<typename Number>
 BlockVector& parallel::distributed::BlockVector< Number >::operator= ( const value_type s )

Copy operator: fill all components of the vector with the given scalar value.

template<typename Number>
 BlockVector& parallel::distributed::BlockVector< Number >::operator= ( const BlockVector< Number > & V )

Copy operator for arguments of the same type. Resize the present vector if necessary.

template<typename Number>
template<class Number2 >
 BlockVector& parallel::distributed::BlockVector< Number >::operator= ( const BlockVector< Number2 > & V )

Copy operator for template arguments of different types. Resize the present vector if necessary.

template<typename Number>
 BlockVector& parallel::distributed::BlockVector< Number >::operator= ( const Vector< Number > & V )

Copy a regular vector into a block vector.

template<typename Number>
 BlockVector& parallel::distributed::BlockVector< Number >::operator= ( const PETScWrappers::MPI::BlockVector< Number > & petsc_vec )

Copy the content of a PETSc vector into the calling vector. This function assumes that the vectors layouts have already been initialized to match.

This operator is only available if deal.II was configured with PETSc.

template<typename Number>
 BlockVector& parallel::distributed::BlockVector< Number >::operator= ( const TrilinosWrappers::MPI::BlockVector< Number > & trilinos_vec )

Copy the content of a Trilinos vector into the calling vector. This function assumes that the vectors layouts have already been initialized to match.

This operator is only available if deal.II was configured with Trilinos.

template<typename Number>
 void parallel::distributed::BlockVector< Number >::reinit ( const size_type num_blocks, const size_type block_size = 0, const bool omit_zeroing_entries = false )

Reinitialize the BlockVector to contain num_blocks blocks of size block_size each.

If the second argument is left at its default value, then the block vector allocates the specified number of blocks but leaves them at zero size. You then need to later reinitialize the individual blocks, and call collect_sizes() to update the block system's knowledge of its individual block's sizes.

If omit_zeroing_entries==false, the vector is filled with zeros.

template<typename Number>
 void parallel::distributed::BlockVector< Number >::reinit ( const std::vector< size_type > & N, const bool omit_zeroing_entries = false )

Reinitialize the BlockVector such that it contains block_sizes.size() blocks. Each block is reinitialized to dimension block_sizes[i].

If the number of blocks is the same as before this function was called, all vectors remain the same and reinit() is called for each vector.

If omit_zeroing_entries==false, the vector is filled with zeros.

Note that you must call this (or the other reinit() functions) function, rather than calling the reinit() functions of an individual block, to allow the block vector to update its caches of vector sizes. If you call reinit() on one of the blocks, then subsequent actions on this object may yield unpredictable results since they may be routed to the wrong block.

template<typename Number>
template<typename Number2 >
 void parallel::distributed::BlockVector< Number >::reinit ( const BlockVector< Number2 > & V, const bool omit_zeroing_entries = false )

Change the dimension to that of the vector V. The same applies as for the other reinit() function.

The elements of V are not copied, i.e. this function is the same as calling reinit (V.size(), omit_zeroing_entries).

Note that you must call this (or the other reinit() functions) function, rather than calling the reinit() functions of an individual block, to allow the block vector to update its caches of vector sizes. If you call reinit() of one of the blocks, then subsequent actions of this object may yield unpredictable results since they may be routed to the wrong block.

template<typename Number>
 void parallel::distributed::BlockVector< Number >::compress ( ::VectorOperation::values operation )

This function copies the data that has accumulated in the data buffer for ghost indices to the owning processor. For the meaning of the argument operation, see the entry on Compressing distributed vectors and matrices in the glossary.

There are two variants for this function. If called with argument VectorOperation::add adds all the data accumulated in ghost elements to the respective elements on the owning processor and clears the ghost array afterwards. If called with argument VectorOperation::insert, a set operation is performed. Since setting elements in a vector with ghost elements is ambiguous (as one can set both the element on the ghost site as well as the owning site), this operation makes the assumption that all data is set correctly on the owning processor. Upon call of compress(VectorOperation::insert), all ghost entries are therefore simply zeroed out (using zero_ghost_values()). In debug mode, a check is performed that makes sure that the data set is actually consistent between processors, i.e., whenever a non-zero ghost element is found, it is compared to the value on the owning processor and an exception is thrown if these elements do not agree.

template<typename Number>
 void parallel::distributed::BlockVector< Number >::update_ghost_values ( ) const

Fills the data field for ghost indices with the values stored in the respective positions of the owning processor. This function is needed before reading from ghosts. The function is const even though ghost data is changed. This is needed to allow functions with a const vector to perform the data exchange without creating temporaries.

template<typename Number>
 void parallel::distributed::BlockVector< Number >::zero_out_ghosts ( )

This method zeros the entries on ghost dofs, but does not touch locally owned DoFs.

After calling this method, read access to ghost elements of the vector is forbidden and an exception is thrown. Only write access to ghost elements is allowed in this state.

template<typename Number>
 bool parallel::distributed::BlockVector< Number >::has_ghost_elements ( ) const

Returns if this Vector contains ghost elements.

template<typename Number>
 bool parallel::distributed::BlockVector< Number >::all_zero ( ) const

Return whether the vector contains only elements with value zero. This function is mainly for internal consistency checks and should seldom be used when not in debug mode since it uses quite some time.

template<typename Number>
 bool parallel::distributed::BlockVector< Number >::is_non_negative ( ) const

Return true if the vector has no negative entries, i.e. all entries are zero or positive. This function is used, for example, to check whether refinement indicators are really all positive (or zero).

The function obviously only makes sense if the template argument of this class is a real type. If it is a complex type, then an exception is thrown.

template<typename Number>
template<typename Number2 >
 bool parallel::distributed::BlockVector< Number >::operator== ( const BlockVector< Number2 > & v ) const

Checks for equality of the two vectors.

template<typename Number>
template<typename Number2 >
 bool parallel::distributed::BlockVector< Number >::operator!= ( const BlockVector< Number2 > & v ) const

Checks for inequality of the two vectors.

template<typename Number>
template<typename Number2 >
 Number parallel::distributed::BlockVector< Number >::operator* ( const BlockVector< Number2 > & V ) const

Perform the inner product of two vectors.

template<typename Number>
 real_type parallel::distributed::BlockVector< Number >::norm_sqr ( ) const

Computes the square of the l2 norm of the vector (i.e., the sum of the squares of all entries among all processors).

template<typename Number>
 Number parallel::distributed::BlockVector< Number >::mean_value ( ) const

Computes the mean value of all the entries in the vector.

template<typename Number>
 real_type parallel::distributed::BlockVector< Number >::l1_norm ( ) const

Returns the l1 norm of the vector (i.e., the sum of the absolute values of all entries among all processors).

template<typename Number>
 real_type parallel::distributed::BlockVector< Number >::l2_norm ( ) const

Returns the l2 norm of the vector (i.e., square root of the sum of the square of all entries among all processors).

template<typename Number>
 real_type parallel::distributed::BlockVector< Number >::lp_norm ( const real_type p ) const

Returns the lp norm with real p of the vector (i.e., the pth root of sum of the pth power of all entries among all processors).

template<typename Number>
 real_type parallel::distributed::BlockVector< Number >::linfty_norm ( ) const

Returns the maximum norm of the vector (i.e., maximum absolute value among all entries among all processors).

template<typename Number>
 Number parallel::distributed::BlockVector< Number >::add_and_dot ( const Number a, const BlockVector< Number > & V, const BlockVector< Number > & W )

Performs a combined operation of a vector addition and a subsequent inner product, returning the value of the inner product. In other words, the result of this function is the same as if the user called

return_value = *this * W;

The reason this function exists is that this operation involves less memory transfer than calling the two functions separately. This method only needs to load three vectors, this, V, W, whereas calling separate methods means to load the calling vector this twice. Since most vector operations are memory transfer limited, this reduces the time by 25% (or 50% if W equals this).

template<typename Number>
template<class BlockVector2 >
 void parallel::distributed::BlockVector< Number >::scale ( const BlockVector2 & v )

Multiply each element of this vector by the corresponding element of v.

template<typename Number>
 void parallel::distributed::BlockVector< Number >::swap ( BlockVector< Number > & v )

Swap the contents of this vector and the other vector v. One could do this operation with a temporary variable and copying over the data elements, but this function is significantly more efficient since it only swaps the pointers to the data of the two vectors and therefore does not need to allocate temporary storage and move data around.

Limitation: right now this function only works if both vectors have the same number of blocks. If needed, the numbers of blocks should be exchanged, too.

This function is analog to the the swap() function of all C++ standard containers. Also, there is a global function swap(u,v) that simply calls u.swap(v), again in analogy to standard functions.

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