Ginkgo  Generated from pipelines/130473384 branch based on develop. Ginkgo version 1.1.1
A numerical linear algebra library targeting many-core architectures
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gko::solver::Fcg< ValueType > Class Template Reference

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 LinOpget_system_matrix () const
 Gets the system operator (matrix) of the linear system. More...
 
const parameters_typeget_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
LinOpapply (const LinOp *b, LinOp *x)
 Applies a linear operator to a vector (or a sequence of vectors). More...
 
const LinOpapply (const LinOp *b, LinOp *x) const
 Applies a linear operator to a vector (or a sequence of vectors). More...
 
LinOpapply (const LinOp *alpha, const LinOp *b, const LinOp *beta, LinOp *x)
 Performs the operation x = alpha * op(b) + beta * x. More...
 
const LinOpapply (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< LinOpcreate_default (std::shared_ptr< const Executor > exec) const
 
std::unique_ptr< LinOpcreate_default () const
 
std::unique_ptr< LinOpclone (std::shared_ptr< const Executor > exec) const
 
std::unique_ptr< LinOpclone () const
 
LinOpcopy_from (const PolymorphicObject *other)
 
LinOpcopy_from (std::unique_ptr< PolymorphicObject > other)
 
LinOpclear ()
 
- 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. More...
 
std::unique_ptr< PolymorphicObjectcreate_default () const
 Creates a new "default" object of the same dynamic type as this object. More...
 
std::unique_ptr< PolymorphicObjectclone (std::shared_ptr< const Executor > exec) const
 Creates a clone of the object. More...
 
std::unique_ptr< PolymorphicObjectclone () const
 Creates a clone of the object. More...
 
PolymorphicObjectcopy_from (const PolymorphicObject *other)
 Copies another object into this object. More...
 
PolymorphicObjectcopy_from (std::unique_ptr< PolymorphicObject > other)
 Moves another object into this object. More...
 
PolymorphicObjectclear ()
 Transforms the object into its default state. More...
 
std::shared_ptr< const Executorget_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...
 
- Public Member Functions inherited from gko::Preconditionable
virtual std::shared_ptr< const LinOpget_preconditioner () const
 Returns the preconditioner operator used by the Preconditionable. More...
 
virtual void set_preconditioner (std::shared_ptr< const LinOp > new_precond)
 Sets the preconditioner operator used by the Preconditionable. 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
ValueTypeprecision of matrix elements

Member Function Documentation

◆ 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: