gko::multigrid::Pgm< ValueType, IndexType > Class Template Reference

Parallel graph match (Pgm) is the aggregate method introduced in the paper M. More...

#include <ginkgo/core/multigrid/pgm.hpp>

Inheritance diagram for gko::multigrid::Pgm< ValueType, IndexType >:

Collaboration diagram for gko::multigrid::Pgm< ValueType, IndexType >:

Classes
class	Factory
struct	parameters_type
class	reuse_data_type
	Records the aggregates, the transfer operators and the coarse-to-fine mappings of the first generate_reuse() call. More...

Public Types
using	value_type = ValueType
using	index_type = IndexType
Public Types inherited from gko::multigrid::EnableMultigridLevel< ValueType >
using	value_type = ValueType
Public Types inherited from gko::UseComposition< ValueType >
using	value_type = ValueType

Public Member Functions
std::shared_ptr< const LinOp >	get_system_matrix () const
	Returns the system operator (matrix) of the linear system. More...
IndexType *	get_agg () noexcept
	Returns the aggregate group. More...
const IndexType *	get_const_agg () const noexcept
	Returns the aggregate group. More...
const parameters_type &	get_parameters () const
Public Member Functions inherited from gko::LinOp
void	apply (ptr_param< const LinOp > b, ptr_param< LinOp > x) const
	Applies a linear operator to a vector (or a sequence of vectors). More...
void	apply (ptr_param< const LinOp > alpha, ptr_param< const LinOp > b, ptr_param< const LinOp > beta, ptr_param< LinOp > x) const
	Performs the operation x = alpha * op(b) + beta * x. More...
const dim< 2 > &	get_size () const noexcept
	Returns the size of the operator. More...
virtual bool	apply_uses_initial_guess () const
	Returns true if the linear operator uses the data given in x as an initial guess. More...
LinOp &	operator= (const LinOp &)=default
	Copy-assigns a LinOp. More...
LinOp &	operator= (LinOp &&other)
	Move-assigns a LinOp. More...
	LinOp (const LinOp &)=default
	Copy-constructs a LinOp. More...
	LinOp (LinOp &&other)
	Move-constructs a LinOp. More...
Public Member Functions inherited from gko::PolymorphicObject
virtual void	validate_data () const
	Throws gko::InvalidData exception if we found the data inside the object does not fulfill certain property up to our knowledge.
PolymorphicObject &	operator= (const PolymorphicObject &)
std::shared_ptr< const Executor >	get_executor () const noexcept
	Returns the Executor of the object. More...
Public Member Functions inherited from gko::log::EnableLogging< PolymorphicObject >
void	add_logger (std::shared_ptr< const Logger > logger) override
void	remove_logger (const Logger *logger) override
void	remove_logger (ptr_param< const Logger > logger)
const std::vector< std::shared_ptr< const Logger > > &	get_loggers () const override
void	clear_loggers () override
Public Member Functions inherited from gko::log::Loggable
void	remove_logger (ptr_param< const Logger > logger)
Public Member Functions inherited from gko::multigrid::EnableMultigridLevel< ValueType >
std::shared_ptr< const LinOp >	get_fine_op () const override
	Returns the operator on fine level. More...
std::shared_ptr< const LinOp >	get_restrict_op () const override
	Returns the restrict operator. More...
std::shared_ptr< const LinOp >	get_coarse_op () const override
	Returns the operator on coarse level. More...
std::shared_ptr< const LinOp >	get_prolong_op () const override
	Returns the prolong operator. More...
Public Member Functions inherited from gko::UseComposition< ValueType >
std::shared_ptr< Composition< ValueType > >	get_composition () const
	Returns the composition operators. More...
std::shared_ptr< const LinOp >	get_operator_at (size_type index) const
	Returns the operator at index-th position of composition. More...

Static Public Member Functions
static auto	build () -> decltype(Factory ::create())
static parameters_type	parse (const config::pnode &config, const config::registry &context, const config::type_descriptor &td_for_child=config::make_type_descriptor< ValueType, IndexType >())
	Create the parameters from the property_tree. More...

Detailed Description

template<typename ValueType = default_precision, typename IndexType = int32>
class gko::multigrid::Pgm< ValueType, IndexType >

Parallel graph match (Pgm) is the aggregate method introduced in the paper M.

Naumov et al., "AmgX: A Library for GPU Accelerated Algebraic Multigrid and Preconditioned Iterative Methods". Current implementation only contains size = 2 version.

Pgm creates the aggregate group according to the matrix value not the structure. Pgm gives two steps (one-phase handshaking) to group the elements. 1: get the strongest neighbor of each unaggregated element. 2: group the elements whose strongest neighbor is each other. repeating until reaching the given conditions. After that, the un-aggregated elements are assigned to an aggregated group or are left alone.

The factory supports LinOpFactory::generate_reuse(): later calls on a matrix with the same sparsity pattern keep the aggregates and only recompute the coarse matrix, so the result can differ from generate(). The aggregates come from the values of the first matrix, so it should be representative of the later ones.

Template Parameters

ValueType	precision of matrix elements
IndexType	precision of matrix indexes

Member Function Documentation

get_agg()

template<typename ValueType = default_precision, typename IndexType = int32>

IndexType* gko::multigrid::Pgm< ValueType, IndexType >::get_agg ( )

inlinenoexcept

Returns the aggregate group.

Aggregate group whose size is same as the number of rows. Stores the mapping information from row index to coarse row index. i.e., agg[row_idx] = coarse_row_idx.

Returns

the aggregate group.

References gko::array< ValueType >::get_data().

get_const_agg()

template<typename ValueType = default_precision, typename IndexType = int32>

const IndexType* gko::multigrid::Pgm< ValueType, IndexType >::get_const_agg ( ) const

inlinenoexcept

Returns the aggregate group.

Aggregate group whose size is same as the number of rows. Stores the mapping information from row index to coarse row index. i.e., agg[row_idx] = coarse_row_idx.

Returns

the aggregate group.

Note

This is the constant version of the function, which can be significantly more memory efficient than the non-constant version, so always prefer this version.

References gko::array< ValueType >::get_const_data().

get_system_matrix()

template<typename ValueType = default_precision, typename IndexType = int32>

std::shared_ptr<const LinOp> gko::multigrid::Pgm< ValueType, IndexType >::get_system_matrix ( ) const

inline

Returns the system operator (matrix) of the linear system.

Returns

the system operator (matrix)

parse()

template<typename ValueType = default_precision, typename IndexType = int32>

static parameters_type gko::multigrid::Pgm< ValueType, IndexType >::parse ( const config::pnode &  config, const config::registry &  context, const config::type_descriptor &  td_for_child = config::make_type_descriptor< ValueType, IndexType >()  )

static

Create the parameters from the property_tree.

Because this is directly tied to the specific type, the value/index type settings within config are ignored and type_descriptor is only used for children configs.

Parameters

config	the property tree for setting
context	the registry
td_for_child	the type descriptor for children configs. The default uses the value/index type of this class.

Returns

parameters

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

• ginkgo/core/distributed/matrix.hpp
• ginkgo/core/multigrid/pgm.hpp