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A numerical linear algebra library targeting many-core architectures
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gko::reorder::Rcm< ValueType, IndexType > Class Template Reference

Rcm (Reverse Cuthill-McKee) is a reordering algorithm minimizing the bandwidth of a matrix. More...

#include <ginkgo/core/reorder/rcm.hpp>

Inheritance diagram for gko::reorder::Rcm< ValueType, IndexType >:
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Collaboration diagram for gko::reorder::Rcm< ValueType, IndexType >:
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Classes

class  Factory
 
struct  parameters_type
 

Public Types

using SparsityMatrix = matrix::SparsityCsr<ValueType, IndexType>
 
using PermutationMatrix = matrix::Permutation<IndexType>
 
using value_type = ValueType
 
using index_type = IndexType
 
- Public Types inherited from gko::EnablePolymorphicAssignment< ConcreteType, ResultType >
using result_type = ResultType
 
- Public Types inherited from gko::ConvertibleTo< ResultType >
using result_type = ResultType
 

Public Member Functions

std::shared_ptr< const PermutationMatrixget_permutation () const
 Gets the permutation (permutation matrix, output of the algorithm) of the linear operator.
 
std::shared_ptr< const PermutationMatrixget_inverse_permutation () const
 Gets the inverse permutation (permutation matrix, output of the algorithm) of the linear operator.
 
const parameters_typeget_parameters () const
 
- Public Member Functions inherited from gko::EnableAbstractPolymorphicObject< AbstractObject, PolymorphicBase >
std::unique_ptr< AbstractObjectcreate_default (std::shared_ptr< const Executor > exec) const
 
std::unique_ptr< AbstractObjectcreate_default () const
 
std::unique_ptr< AbstractObjectclone (std::shared_ptr< const Executor > exec) const
 
std::unique_ptr< AbstractObjectclone () const
 
AbstractObjectcopy_from (const PolymorphicObject *other)
 
template<typename Derived >
std::enable_if_t< std::is_base_of< PolymorphicObject, std::decay_t< Derived > >::value, AbstractObject > * copy_from (std::unique_ptr< Derived > &&other)
 
template<typename Derived >
std::enable_if_t< std::is_base_of< PolymorphicObject, std::decay_t< Derived > >::value, AbstractObject > * copy_from (const std::unique_ptr< Derived > &other)
 
AbstractObjectcopy_from (const std::shared_ptr< const PolymorphicObject > &other)
 
AbstractObjectmove_from (ptr_param< PolymorphicObject > other)
 
AbstractObjectclear ()
 
- Public Member Functions inherited from gko::PolymorphicObject
PolymorphicObjectoperator= (const PolymorphicObject &)
 
std::unique_ptr< PolymorphicObjectcreate_default (std::shared_ptr< const Executor > exec) const
 Creates a new "default" object of the same dynamic type as this object.
 
std::unique_ptr< PolymorphicObjectcreate_default () const
 Creates a new "default" object of the same dynamic type as this object.
 
std::unique_ptr< PolymorphicObjectclone (std::shared_ptr< const Executor > exec) const
 Creates a clone of the object.
 
std::unique_ptr< PolymorphicObjectclone () const
 Creates a clone of the object.
 
PolymorphicObjectcopy_from (const PolymorphicObject *other)
 Copies another object into this object.
 
template<typename Derived , typename Deleter >
std::enable_if_t< std::is_base_of< PolymorphicObject, std::decay_t< Derived > >::value, PolymorphicObject > * copy_from (std::unique_ptr< Derived, Deleter > &&other)
 Moves another object into this object.
 
template<typename Derived , typename Deleter >
std::enable_if_t< std::is_base_of< PolymorphicObject, std::decay_t< Derived > >::value, PolymorphicObject > * copy_from (const std::unique_ptr< Derived, Deleter > &other)
 Copies another object into this object.
 
PolymorphicObjectcopy_from (const std::shared_ptr< const PolymorphicObject > &other)
 Copies another object into this object.
 
PolymorphicObjectmove_from (ptr_param< PolymorphicObject > other)
 Moves another object into this object.
 
PolymorphicObjectclear ()
 Transforms the object into its default state.
 
std::shared_ptr< const Executorget_executor () const noexcept
 Returns the Executor of the object.
 
- Public Member Functions inherited from gko::log::EnableLogging< PolymorphicObject >
void add_logger (std::shared_ptr< const Logger > logger) override
 Adds a new logger to the list of subscribed loggers.
 
void remove_logger (const Logger *logger) override
 Removes a logger from the list of subscribed loggers.
 
void remove_logger (ptr_param< const Logger > logger)
 
const std::vector< std::shared_ptr< const Logger > > & get_loggers () const override
 Returns the vector containing all loggers registered at this object.
 
void clear_loggers () override
 Remove all loggers registered at this object.
 
- Public Member Functions inherited from gko::log::Loggable
void remove_logger (ptr_param< const Logger > logger)
 
- Public Member Functions inherited from gko::EnablePolymorphicAssignment< ConcreteType, ResultType >
void convert_to (result_type *result) const override
 Converts the implementer to an object of type result_type.
 
void move_to (result_type *result) override
 Converts the implementer to an object of type result_type by moving data from this object.
 
- Public Member Functions inherited from gko::ConvertibleTo< ResultType >
void convert_to (ptr_param< result_type > result) const
 
void move_to (ptr_param< result_type > result)
 

Static Public Member Functions

static auto build () -> decltype(Factory ::create())
 

Friends

class EnablePolymorphicObject< Rcm, ReorderingBase< IndexType > >
 

Detailed Description

template<typename ValueType = default_precision, typename IndexType = int32>
class gko::reorder::Rcm< ValueType, IndexType >

Rcm (Reverse Cuthill-McKee) is a reordering algorithm minimizing the bandwidth of a matrix.

Such a reordering typically also significantly reduces fill-in, though usually not as effective as more complex algorithms, specifically AMD and nested dissection schemes. The advantage of this algorithm is its low runtime. It requires the input matrix to be structurally symmetric.

Note
This class is derived from polymorphic object but is not a LinOp as it does not make sense for this class to implement the apply methods. The objective of this class is to generate a reordering/permutation vector (in the form of the Permutation matrix), which can be used to apply to reorder a matrix as required.

There are two "starting strategies" currently available: minimum degree and pseudo-peripheral. These strategies control how a starting vertex for a connected component is chosen, which is then renumbered as first vertex in the component, starting the algorithm from there. In general, the bandwidths obtained by choosing a pseudo-peripheral vertex are slightly smaller than those obtained from choosing a vertex of minimum degree. On the other hand, this strategy is much more expensive, relatively. The algorithm for finding a pseudo-peripheral vertex as described in "Computer Solution of Sparse Linear Systems" (George, Liu, Ng, Oak Ridge National Laboratory, 1994) is implemented here.

Template Parameters
ValueTypeType of the values of all matrices used in this class
IndexTypeType of the indices of all matrices used in this class

Member Function Documentation

◆ get_inverse_permutation()

template<typename ValueType = default_precision, typename IndexType = int32>
std::shared_ptr< const PermutationMatrix > gko::reorder::Rcm< ValueType, IndexType >::get_inverse_permutation ( ) const
inline

Gets the inverse permutation (permutation matrix, output of the algorithm) of the linear operator.

Returns
the inverse permutation (permutation matrix)

◆ get_permutation()

template<typename ValueType = default_precision, typename IndexType = int32>
std::shared_ptr< const PermutationMatrix > gko::reorder::Rcm< ValueType, IndexType >::get_permutation ( ) const
inline

Gets the permutation (permutation matrix, output of the algorithm) of the linear operator.

Returns
the permutation (permutation matrix)

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