FCG or the flexible conjugate gradient method is an iterative type Krylov subspace method which is suitable for symmetric positive definite methods. More...

#include <ginkgo/core/solver/fcg.hpp>

Collaboration diagram for gko::solver::Fcg< ValueType >:

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Classes
class	Factory

struct	parameters_type

Public Types
using	value_type = ValueType

Public Types inherited from gko::EnablePolymorphicAssignment< Fcg< ValueType > >
using	result_type = Fcg< ValueType >

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

Public Member Functions
std::shared_ptr< const LinOp >	get_system_matrix () const
	Gets the system operator (matrix) of the linear system. More...

std::shared_ptr< const LinOp >	get_preconditioner () const override
	Returns the preconditioner operator used by the solver. More...

const parameters_type &	get_parameters () const

Public Member Functions inherited from gko::EnableLinOp< Fcg< ValueType > >
const Fcg< ValueType > *	apply (const LinOp b, LinOp x) const

Fcg< ValueType > *	apply (const LinOp b, LinOp x)

const Fcg< ValueType > *	apply (const LinOp alpha, const LinOp b, const LinOp beta, LinOp x) const

Fcg< ValueType > *	apply (const LinOp alpha, const LinOp b, const LinOp beta, LinOp x)

Public Member Functions inherited from gko::EnableAbstractPolymorphicObject< Fcg< ValueType >, LinOp >
std::unique_ptr< Fcg< ValueType > >	create_default (std::shared_ptr< const Executor > exec) const

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

std::unique_ptr< Fcg< ValueType > >	clone (std::shared_ptr< const Executor > exec) const

std::unique_ptr< Fcg< ValueType > >	clone () const

Fcg< ValueType > *	copy_from (const PolymorphicObject *other)

Fcg< ValueType > *	copy_from (std::unique_ptr< PolymorphicObject > other)

Fcg< ValueType > *	clear ()

Public Member Functions inherited from gko::LinOp
LinOp *	apply (const LinOp b, LinOp x)
	Applies a linear operator to a vector (or a sequence of vectors). More...

const LinOp *	apply (const LinOp b, LinOp x) const
	Applies a linear operator to a vector (or a sequence of vectors). More...

LinOp *	apply (const LinOp alpha, const LinOp b, const LinOp beta, LinOp x)
	Performs the operation x = alpha * op(b) + beta * x. More...

const LinOp *	apply (const LinOp alpha, const LinOp b, const LinOp beta, 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...

Public Member Functions inherited from gko::EnableAbstractPolymorphicObject< LinOp >
std::unique_ptr< LinOp >	create_default (std::shared_ptr< const Executor > exec) const

std::unique_ptr< LinOp >	create_default () const

std::unique_ptr< LinOp >	clone (std::shared_ptr< const Executor > exec) const

std::unique_ptr< LinOp >	clone () const

LinOp *	copy_from (const PolymorphicObject *other)

LinOp *	copy_from (std::unique_ptr< PolymorphicObject > other)

LinOp *	clear ()

Public Member Functions inherited from gko::PolymorphicObject
PolymorphicObject &	operator= (const PolymorphicObject &)

std::unique_ptr< PolymorphicObject >	create_default (std::shared_ptr< const Executor > exec) const
	Creates a new "default" object of the same dynamic type as this object. More...

std::unique_ptr< PolymorphicObject >	create_default () const
	Creates a new "default" object of the same dynamic type as this object. More...

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

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

PolymorphicObject *	copy_from (const PolymorphicObject *other)
	Copies another object into this object. More...

PolymorphicObject *	copy_from (std::unique_ptr< PolymorphicObject > other)
	Moves another object into this object. More...

PolymorphicObject *	clear ()
	Transforms the object into its default state. More...

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
	Adds a new logger to the list of subscribed loggers. More...

void	remove_logger (const Logger *logger) override
	Removes a logger from the list of subscribed loggers. More...

Public Member Functions inherited from gko::EnablePolymorphicAssignment< Fcg< ValueType > >
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...

Static Public Member Functions
static auto	build () -> decltype(Factory ::create())

Friends
class	EnableLinOp< Fcg >

class	EnablePolymorphicObject< Fcg, LinOp >

Detailed Description

template<typename ValueType = default_precision>
class gko::solver::Fcg< ValueType >

FCG or the flexible conjugate gradient method is an iterative type Krylov subspace method which is suitable for symmetric positive definite methods.

Though this method performs very well for symmetric positive definite matrices, it is in general not suitable for general matrices.

In contrast to the standard CG based on the Polack-Ribiere formula, the flexible CG uses the Fletcher-Reeves formula for creating the orthonormal vectors spanning the Krylov subspace. This increases the computational cost of every Krylov solver iteration but allows for non-constant preconditioners.

The implementation in Ginkgo makes use of the merged kernel to make the best use of data locality. The inner operations in one iteration of FCG are merged into 2 separate steps.

Template Parameters

ValueType precision of matrix elements

Member Function Documentation

◆ get_preconditioner()

template<typename ValueType = default_precision>

std::shared_ptr<const LinOp> gko::solver::Fcg< ValueType >::get_preconditioner ( ) const

inlineoverridevirtual

Returns the preconditioner operator used by the solver.

Returns: the preconditioner operator used by the solver

Implements gko::Preconditionable.

◆ get_system_matrix()

template<typename ValueType = default_precision>

std::shared_ptr<const LinOp> gko::solver::Fcg< ValueType >::get_system_matrix ( ) const

inline

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

Returns: the system operator (matrix)

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

ginkgo/core/solver/fcg.hpp (f1a4eb68)

Classes

Public Types

Public Member Functions

Static Public Member Functions

Friends

Detailed Description

template<typename ValueType = default_precision> class gko::solver::Fcg< ValueType >

Member Function Documentation

◆ get_preconditioner()

◆ get_system_matrix()

template<typename ValueType = default_precision>
class gko::solver::Fcg< ValueType >