Reference documentation for deal.II version Git ab1cc5b 2017-03-24 06:23:49 -0600
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DynamicSparsityPattern Class Reference

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

Inheritance diagram for DynamicSparsityPattern:
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Classes

struct  Line
 

Public Types

typedef types::global_dof_index size_type
 
typedef DynamicSparsityPatternIterators::Iterator iterator
 
typedef DynamicSparsityPatternIterators::Iterator const_iterator
 

Public Member Functions

 DynamicSparsityPattern ()
 
 DynamicSparsityPattern (const DynamicSparsityPattern &)
 
 DynamicSparsityPattern (const size_type m, const size_type n, const IndexSet &rowset=IndexSet())
 
 DynamicSparsityPattern (const IndexSet &indexset)
 
 DynamicSparsityPattern (const size_type n)
 
DynamicSparsityPatternoperator= (const DynamicSparsityPattern &)
 
void reinit (const size_type m, const size_type n, const IndexSet &rowset=IndexSet())
 
void compress ()
 
bool empty () const
 
size_type max_entries_per_row () const
 
void add (const size_type i, const size_type j)
 
template<typename ForwardIterator >
void add_entries (const size_type row, ForwardIterator begin, ForwardIterator end, const bool indices_are_unique_and_sorted=false)
 
bool exists (const size_type i, const size_type j) const
 
void symmetrize ()
 
void print (std::ostream &out) const
 
void print_gnuplot (std::ostream &out) const
 
size_type n_rows () const
 
size_type n_cols () const
 
size_type row_length (const size_type row) const
 
size_type column_number (const size_type row, const size_type index) const
 
size_type bandwidth () const
 
size_type n_nonzero_elements () const
 
const IndexSetrow_index_set () const
 
size_type memory_consumption () const
 
Iterators
iterator begin () const
 
iterator end () const
 
iterator begin (const size_type r) const
 
iterator end (const size_type r) 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=0) const
 
void unsubscribe (const char *identifier=0) const
 
unsigned int n_subscriptions () const
 
void list_subscribers () const
 
template<class Archive >
void serialize (Archive &ar, const unsigned int version)
 

Static Public Member Functions

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

Private Attributes

bool have_entries
 
size_type rows
 
size_type cols
 
IndexSet rowset
 
std::vector< Linelines
 

Friends

class DynamicSparsityPatternIterators::Accessor
 

Detailed Description

This class acts as an intermediate form of the SparsityPattern class. From the interface it mostly represents a SparsityPattern object that is kept compressed at all times. However, since the final sparsity pattern is not known while constructing it, keeping the pattern compressed at all times can only be achieved at the expense of either increased memory or run time consumption upon use. The main purpose of this class is to avoid some memory bottlenecks, so we chose to implement it memory conservative. The chosen data format is too unsuited to be used for actual matrices, though. It is therefore necessary to first copy the data of this object over to an object of type SparsityPattern before using it in actual matrices.

Another viewpoint is that this class does not need up front allocation of a certain amount of memory, but grows as necessary. An extensive description of sparsity patterns can be found in the documentation of the Sparsity patterns module.

This class is an example of the "dynamic" type of Sparsity patterns. It is used in most tutorial programs in one way or another.

Interface

Since this class is intended as an intermediate replacement of the SparsityPattern class, it has mostly the same interface, with small changes where necessary. In particular, the add() function, and the functions inquiring properties of the sparsity pattern are the same.

Usage

Use this class as follows:

DynamicSparsityPattern dynamic_pattern (dof_handler.n_dofs());
dynamic_pattern);
constraints.condense (dynamic_pattern);
sp.copy_from (dynamic_pattern);
Author
Timo Heister, 2008

Definition at line 289 of file dynamic_sparsity_pattern.h.

Member Typedef Documentation

Declare the type for container size.

Definition at line 295 of file dynamic_sparsity_pattern.h.

Typedef an for iterator class that allows to walk over all nonzero elements of a sparsity pattern.

Since the iterator does not allow to modify the sparsity pattern, this type is the same as that for const_iterator.

Definition at line 306 of file dynamic_sparsity_pattern.h.

Typedef for an iterator class that allows to walk over all nonzero elements of a sparsity pattern.

Definition at line 314 of file dynamic_sparsity_pattern.h.

Constructor & Destructor Documentation

DynamicSparsityPattern::DynamicSparsityPattern ( )

Initialize as an empty object. This is useful if you want such objects as member variables in other classes. You can make the structure usable by calling the reinit() function.

Definition at line 217 of file dynamic_sparsity_pattern.cc.

DynamicSparsityPattern::DynamicSparsityPattern ( const DynamicSparsityPattern s)

Copy constructor. This constructor is only allowed to be called if the sparsity structure to be copied is empty. This is so in order to prevent involuntary copies of objects for temporaries, which can use large amounts of computing time. However, copy constructors are needed if you want to place a DynamicSparsityPattern in a container, e.g. to write such statements like v.push_back (DynamicSparsityPattern());, with v a vector of DynamicSparsityPattern objects.

Definition at line 228 of file dynamic_sparsity_pattern.cc.

DynamicSparsityPattern::DynamicSparsityPattern ( const size_type  m,
const size_type  n,
const IndexSet rowset = IndexSet() 
)

Initialize a rectangular sparsity pattern with m rows and n columns. The rowset restricts the storage to elements in rows of this set. Adding elements outside of this set has no effect. The default argument keeps all entries.

Definition at line 245 of file dynamic_sparsity_pattern.cc.

DynamicSparsityPattern::DynamicSparsityPattern ( const IndexSet indexset)

Create a square SparsityPattern using the given index set. The total size is given by the size of indexset and only rows corresponding to indices in indexset are stored on the current processor.

Definition at line 259 of file dynamic_sparsity_pattern.cc.

DynamicSparsityPattern::DynamicSparsityPattern ( const size_type  n)

Initialize a square pattern of dimension n.

Definition at line 270 of file dynamic_sparsity_pattern.cc.

Member Function Documentation

DynamicSparsityPattern & DynamicSparsityPattern::operator= ( const DynamicSparsityPattern s)

Copy operator. For this the same holds as for the copy constructor: it is declared, defined and fine to be called, but the latter only for empty objects.

Definition at line 283 of file dynamic_sparsity_pattern.cc.

void DynamicSparsityPattern::reinit ( const size_type  m,
const size_type  n,
const IndexSet rowset = IndexSet() 
)

Reallocate memory and set up data structures for a new sparsity pattern with m rows and n columns. The rowset restricts the storage to elements in rows of this set. Adding elements outside of this set has no effect. The default argument keeps all entries.

Definition at line 301 of file dynamic_sparsity_pattern.cc.

void DynamicSparsityPattern::compress ( )

Since this object is kept compressed at all times anyway, this function does nothing, but is declared to make the interface of this class as much alike as that of the SparsityPattern class.

Definition at line 325 of file dynamic_sparsity_pattern.cc.

bool DynamicSparsityPattern::empty ( ) const

Return whether the object is empty. It is empty if no memory is allocated, which is the same as that both dimensions are zero.

Definition at line 331 of file dynamic_sparsity_pattern.cc.

DynamicSparsityPattern::size_type DynamicSparsityPattern::max_entries_per_row ( ) const

Return the maximum number of entries per row. Note that this number may change as entries are added.

Definition at line 339 of file dynamic_sparsity_pattern.cc.

void DynamicSparsityPattern::add ( const size_type  i,
const size_type  j 
)
inline

Add a nonzero entry. If the entry already exists, this call does nothing.

Definition at line 948 of file dynamic_sparsity_pattern.h.

template<typename ForwardIterator >
void DynamicSparsityPattern::add_entries ( const size_type  row,
ForwardIterator  begin,
ForwardIterator  end,
const bool  indices_are_unique_and_sorted = false 
)
inline

Add several nonzero entries to the specified row. Already existing entries are ignored.

Definition at line 969 of file dynamic_sparsity_pattern.h.

bool DynamicSparsityPattern::exists ( const size_type  i,
const size_type  j 
) const

Check if a value at a certain position may be non-zero.

Definition at line 356 of file dynamic_sparsity_pattern.cc.

void DynamicSparsityPattern::symmetrize ( )

Make the sparsity pattern symmetric by adding the sparsity pattern of the transpose object.

This function throws an exception if the sparsity pattern does not represent a square matrix.

Definition at line 377 of file dynamic_sparsity_pattern.cc.

void DynamicSparsityPattern::print ( std::ostream &  out) const

Print the sparsity pattern. The output consists of one line per row of the format [i,j1,j2,j3,...]. i is the row number and jn are the allocated columns in this row.

Definition at line 411 of file dynamic_sparsity_pattern.cc.

void DynamicSparsityPattern::print_gnuplot ( std::ostream &  out) const

Print the sparsity pattern in a format that gnuplot understands and which can be used to plot the sparsity pattern in a graphical way. The format consists of pairs i j of nonzero elements, each representing one entry, one per line of the output file. Indices are counted from zero on, as usual. Since sparsity patterns are printed in the same way as matrices are displayed, we print the negative of the column index, which means that the (0,0) element is in the top left rather than in the bottom left corner.

Print the sparsity pattern in gnuplot by setting the data style to dots or points and use the plot command.

Definition at line 431 of file dynamic_sparsity_pattern.cc.

DynamicSparsityPattern::size_type DynamicSparsityPattern::n_rows ( ) const
inline

Return the number of rows, which equals the dimension of the image space.

Definition at line 930 of file dynamic_sparsity_pattern.h.

types::global_dof_index DynamicSparsityPattern::n_cols ( ) const
inline

Return the number of columns, which equals the dimension of the range space.

Definition at line 939 of file dynamic_sparsity_pattern.h.

types::global_dof_index DynamicSparsityPattern::row_length ( const size_type  row) const
inline

Number of entries in a specific row. This function can only be called if the given row is a member of the index set of rows that we want to store.

Definition at line 997 of file dynamic_sparsity_pattern.h.

types::global_dof_index DynamicSparsityPattern::column_number ( const size_type  row,
const size_type  index 
) const
inline

Access to column number field. Return the column number of the indexth entry in row.

Definition at line 1016 of file dynamic_sparsity_pattern.h.

DynamicSparsityPattern::iterator DynamicSparsityPattern::begin ( ) const
inline

Iterator starting at the first entry of the matrix. The resulting iterator can be used to walk over all nonzero entries of the sparsity pattern.

Note the discussion in the general documentation of this class about the order in which elements are accessed.

Note
If the sparsity pattern has been initialized with an IndexSet that denotes which rows to store, then iterators will simply skip over rows that are not stored. In other words, they will look like empty rows, but no exception will be generated when iterating over such rows.

Definition at line 1032 of file dynamic_sparsity_pattern.h.

DynamicSparsityPattern::iterator DynamicSparsityPattern::end ( ) const
inline

Final iterator.

Definition at line 1040 of file dynamic_sparsity_pattern.h.

DynamicSparsityPattern::iterator DynamicSparsityPattern::begin ( const size_type  r) const
inline

Iterator starting at the first entry of row r.

Note that if the given row is empty, i.e. does not contain any nonzero entries, then the iterator returned by this function equals end(r). Note also that the iterator may not be dereferencable in that case.

Note also the discussion in the general documentation of this class about the order in which elements are accessed.

Note
If the sparsity pattern has been initialized with an IndexSet that denotes which rows to store, then iterators will simply skip over rows that are not stored. In other words, they will look like empty rows, but no exception will be generated when iterating over such rows.

Definition at line 1049 of file dynamic_sparsity_pattern.h.

DynamicSparsityPattern::iterator DynamicSparsityPattern::end ( const size_type  r) const
inline

Final iterator of row r. It points to the first element past the end of line r, or past the end of the entire sparsity pattern.

Note that the end iterator is not necessarily dereferencable. This is in particular the case if it is the end iterator for the last row of a matrix.

Definition at line 1109 of file dynamic_sparsity_pattern.h.

DynamicSparsityPattern::size_type DynamicSparsityPattern::bandwidth ( ) const

Compute the bandwidth of the matrix represented by this structure. The bandwidth is the maximum of \(|i-j|\) for which the index pair \((i,j)\) represents a nonzero entry of the matrix.

Definition at line 458 of file dynamic_sparsity_pattern.cc.

DynamicSparsityPattern::size_type DynamicSparsityPattern::n_nonzero_elements ( ) const

Return the number of nonzero elements allocated through this sparsity pattern.

Definition at line 479 of file dynamic_sparsity_pattern.cc.

const IndexSet & DynamicSparsityPattern::row_index_set ( ) const
inline

Return the IndexSet that sets which rows are active on the current processor. It corresponds to the IndexSet given to this class in the constructor or in the reinit function.

Definition at line 1124 of file dynamic_sparsity_pattern.h.

bool DynamicSparsityPattern::stores_only_added_elements ( )
inlinestatic

return whether this object stores only those entries that have been added explicitly, or if the sparsity pattern contains elements that have been added through other means (implicitly) while building it. For the current class, the result is always true.

This function mainly serves the purpose of describing the current class in cases where several kinds of sparsity patterns can be passed as template arguments.

Definition at line 1133 of file dynamic_sparsity_pattern.h.

DynamicSparsityPattern::size_type DynamicSparsityPattern::memory_consumption ( ) const

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

Definition at line 495 of file dynamic_sparsity_pattern.cc.

Member Data Documentation

bool DynamicSparsityPattern::have_entries
private

A flag that stores whether any entries have been added so far.

Definition at line 567 of file dynamic_sparsity_pattern.h.

size_type DynamicSparsityPattern::rows
private

Number of rows that this sparsity structure shall represent.

Definition at line 572 of file dynamic_sparsity_pattern.h.

size_type DynamicSparsityPattern::cols
private

Number of columns that this sparsity structure shall represent.

Definition at line 577 of file dynamic_sparsity_pattern.h.

IndexSet DynamicSparsityPattern::rowset
private

A set that contains the valid rows.

Definition at line 583 of file dynamic_sparsity_pattern.h.

std::vector<Line> DynamicSparsityPattern::lines
private

Actual data: store for each row the set of nonzero entries.

Definition at line 629 of file dynamic_sparsity_pattern.h.


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