NullspaceProjection wraps a preconditioner \( M \) with projections onto the complement of a nullspace, \( z = P M Q r \). More...

#include <ginkgo/core/preconditioner/nullspace_projection.hpp>

Inheritance diagram for gko::preconditioner::NullspaceProjection< ValueType >:

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Collaboration diagram for gko::preconditioner::NullspaceProjection< ValueType >:

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Classes
class	Factory

struct	parameters_type

Public Types
using	value_type = ValueType

Public Types inherited from gko::EnableCloneable< NullspaceProjection< ValueType > >
using	result_type = NullspaceProjection< ValueType >

Public Types inherited from gko::ConvertibleTo< ResultType >
using	result_type = ResultType

Public Member Functions
std::shared_ptr< const LinOp >	get_preconditioner () const

std::shared_ptr< const solver::Nullspace< ValueType > >	get_nullspace () const

std::shared_ptr< const solver::Nullspace< ValueType > >	get_left_nullspace () const

std::unique_ptr< LinOp >	transpose () const override
	Returns a LinOp representing the transpose of the Transposable object. More...

std::unique_ptr< LinOp >	conj_transpose () const override
	Returns a LinOp representing the conjugate transpose of the Transposable object. More...

NullspaceProjection &	operator= (const NullspaceProjection &other)

NullspaceProjection &	operator= (NullspaceProjection &&other)

	NullspaceProjection (const NullspaceProjection &other)

	NullspaceProjection (NullspaceProjection &&other)

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::EnableCloneable< NullspaceProjection< ValueType > >
std::unique_ptr< NullspaceProjection< ValueType > >	clone (std::shared_ptr< const Executor > exec) const
	Creates a clone of the object. More...

std::unique_ptr< NullspaceProjection< ValueType > >	clone () const
	Creates a clone of the object. More...

void	convert_to (result_type *result) const override
	Converts the implementer to an object of type result_type. More...

void	move_to (result_type *result) override
	Converts the implementer to an object of type result_type by moving data from this object. More...

std::unique_ptr< NullspaceProjection< ValueType > >	create_default () const

std::unique_ptr< NullspaceProjection< ValueType > >	create_default (std::shared_ptr< const Executor > exec) const

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)

Public Member Functions inherited from gko::Cloneable
std::unique_ptr< Cloneable >	clone (std::shared_ptr< const Executor > exec) const

std::unique_ptr< Cloneable >	clone () const

Cloneable *	copy_from (ptr_param< const Cloneable > other)

Cloneable *	move_from (ptr_param< Cloneable > other)

std::unique_ptr< Cloneable >	create_default (std::shared_ptr< const Executor > exec) const

std::unique_ptr< Cloneable >	create_default () const

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 >())
	Create the parameters from the property_tree. More...

Friends
class	EnableCloneable< NullspaceProjection >

Detailed Description

template<typename ValueType = default_precision>
class gko::preconditioner::NullspaceProjection< ValueType >

NullspaceProjection wraps a preconditioner \( M \) with projections onto the complement of a nullspace, \( z = P M Q r \).

\( P \) removes the nullspace from the preconditioned vector, which keeps the search directions of a Krylov solver, and thus its solution, orthogonal to the nullspace. The optional \( Q \) removes the left nullspace from the input. If both are the same nullspace, \( P M P \) is symmetric for a symmetric \( M \), which solvers like Minres need on ill-conditioned problems or when iterated past convergence.

Iterative solvers that support nullspaces (see solver::nullspace_traits) wrap their preconditioner in a NullspaceProjection when their nullspace parameter is set, unless it already is one removing the nullspace. It can also be used as the preconditioner of any solver directly; then the right-hand side and the initial guess need to be projected by the user, see solver::Nullspace::project.

A constant-only nullspace is adapted to the size and value type of the system matrix, so the factory can be used for matrices of any size.

Template Parameters

ValueType the value type of the vectors

Member Function Documentation

◆ conj_transpose()

template<typename ValueType = default_precision>

std::unique_ptr<LinOp> gko::preconditioner::NullspaceProjection< ValueType >::conj_transpose ( ) const

overridevirtual

Returns a LinOp representing the conjugate transpose of the Transposable object.

Returns: a pointer to the new conjugate transposed object

Implements gko::Transposable.

◆ get_left_nullspace()

template<typename ValueType = default_precision>

std::shared_ptr<const solver::Nullspace<ValueType> > gko::preconditioner::NullspaceProjection< ValueType >::get_left_nullspace ( ) const

Returns: the left nullspace removed before the preconditioner, or nullptr if there is none

◆ get_nullspace()

template<typename ValueType = default_precision>

std::shared_ptr<const solver::Nullspace<ValueType> > gko::preconditioner::NullspaceProjection< ValueType >::get_nullspace ( ) const

Returns: the nullspace removed after the preconditioner, or nullptr if there is none

◆ get_preconditioner()

template<typename ValueType = default_precision>

std::shared_ptr<const LinOp> gko::preconditioner::NullspaceProjection< ValueType >::get_preconditioner ( ) const

Returns: the wrapped preconditioner

◆ parse()

template<typename ValueType = default_precision>

static parameters_type gko::preconditioner::NullspaceProjection< ValueType >::parse	(	const config::pnode &	config,
		const config::registry &	context,
		const config::type_descriptor &	td_for_child = `config::make_type_descriptor< ValueType >()`
	)

static

Create the parameters from the property_tree.

Because this is directly tied to the specific type, the value type in the property tree is ignored. The nullspaces and the generated preconditioner are read from the registry.

Parameters

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

Returns: parameters

◆ transpose()

template<typename ValueType = default_precision>

std::unique_ptr<LinOp> gko::preconditioner::NullspaceProjection< ValueType >::transpose ( ) const

overridevirtual

Returns a LinOp representing the transpose of the Transposable object.

Returns: a pointer to the new transposed object

Implements gko::Transposable.

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

ginkgo/core/preconditioner/nullspace_projection.hpp

Classes

Public Types

Public Member Functions

Static Public Member Functions

Friends

Detailed Description

template<typename ValueType = default_precision> class gko::preconditioner::NullspaceProjection< ValueType >

Member Function Documentation

◆ conj_transpose()

◆ get_left_nullspace()

◆ get_nullspace()

◆ get_preconditioner()

◆ parse()

◆ transpose()

template<typename ValueType = default_precision>
class gko::preconditioner::NullspaceProjection< ValueType >