The Incomplete LU (ILU) preconditioner solves the equation \(LUx = b\) for a given lower triangular matrix \(L\), an upper triangular matrix \(U\) and the right hand side \(b\) (can contain multiple right hand sides). More...

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

Inheritance diagram for gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >:

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Collaboration diagram for gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >:

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Classes
class	Factory

struct	parameters_type

Public Types
using	value_type = ValueType

using	index_type = IndexType

using	transposed_type = Ilu

Public Member Functions
const parameters_type &	get_parameters () const

std::shared_ptr< const LinOp >	get_l_solver () const
	Returns the solver which is used for the provided \(L\) matrix. More...

std::shared_ptr< const LinOp >	get_u_solver () const
	Returns the solver which is used for the provided \(U\) matrix. More...

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...

Ilu &	operator= (const Ilu &other)
	Copy-assigns an ILU preconditioner. More...

Ilu &	operator= (Ilu &&other)
	Move-assigns an ILU preconditioner. More...

	Ilu (const Ilu &other)
	Copy-constructs an ILU preconditioner. More...

	Ilu (Ilu &&other)
	Move-constructs an ILU preconditioner. More...

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)

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< value_type, index_type >())
	Create the parameters from the property_tree. More...

Static Public Attributes
static constexpr bool	performs_reverse_apply = ReverseApply

Detailed Description

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>
class gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >

The Incomplete LU (ILU) preconditioner solves the equation \(LUx = b\) for a given lower triangular matrix \(L\), an upper triangular matrix \(U\) and the right hand side \(b\) (can contain multiple right hand sides).

It allows to set both the solver for \(L\) and the solver for \(U\) independently, while providing the defaults solver::LowerTrs and solver::UpperTrs, which are direct triangular solvers. For these solvers, a factory can be provided (with with_l_solver and with_u_solver) to have more control over their behavior. In particular, it is possible to use an iterative method for solving the triangular systems.

An object of this class can be created with a matrix or a gko::Composition containing two matrices. If created with a matrix, it is factorized before creating the solver. If a gko::Composition (containing two matrices) is used, the first operand will be taken as the \(L\) matrix, the second will be considered the \(U\) matrix. ParIlu can be directly used, since it orders the factors in the correct way.

Note: When providing a gko::Composition, the first matrix must be the lower matrix ( \(L\)), and the second matrix must be the upper matrix ( \(U\)). If they are swapped, solving might crash or return the wrong result.; Do not use symmetric solvers (like CG) for \(L\) or \(U\) solvers since both matrices ( \(L\) and \(U\)) are, by design, not symmetric.; This class is not thread safe (even a const object is not) because it uses an internal cache to accelerate multiple (sequential) applies. Using it in parallel can lead to segmentation faults, wrong results and other unwanted behavior.; The default template during parse is <ValueType, IndexType> not <LowerTrs, IndexType>. Only the variants with ValueType are supported in parse.

Template Parameters

ValueType	the value type used for the \(L\) and \(U\) matrices.
ReverseApply	default behavior (ReverseApply = false) is first to solve with \(L\) ( \(Ly = b\)) and then with \(U\) ( \(Ux = y\)). When set to true, it will solve first with \(U\), and then with \(L\).
IndexType	Type of the indices when ParIlu is used to generate both \(L\) and \(U\) factors. Irrelevant otherwise.

Constructor & Destructor Documentation

◆ Ilu() [1/2]

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>

gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >::Ilu ( const Ilu< ValueType, ReverseApply, IndexType > & other )

Copy-constructs an ILU preconditioner.

Inherits the executor, shallow-copies the solvers and parameters.

◆ Ilu() [2/2]

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>

gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >::Ilu ( Ilu< ValueType, ReverseApply, IndexType > && other )

Move-constructs an ILU preconditioner.

Inherits the executor, moves the solvers and parameters. The moved-from object is empty (0x0 with nullptr solvers and default parameters)

Member Function Documentation

◆ conj_transpose()

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>

std::unique_ptr<LinOp> gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >::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_l_solver()

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>

std::shared_ptr<const LinOp> gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >::get_l_solver ( ) const

inline

Returns the solver which is used for the provided \(L\) matrix.

Returns: the solver which is used for the provided \(L\) matrix

◆ get_u_solver()

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>

std::shared_ptr<const LinOp> gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >::get_u_solver ( ) const

inline

Returns the solver which is used for the provided \(U\) matrix.

Returns: the solver which is used for the provided \(U\) matrix

◆ operator=() [1/2]

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>

Ilu& gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >::operator= ( const Ilu< ValueType, ReverseApply, IndexType > & other )

Copy-assigns an ILU preconditioner.

Preserves the executor, shallow-copies the solvers and parameters. Creates a clone of the solvers if they are on the wrong executor.

◆ operator=() [2/2]

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>

Ilu& gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >::operator= ( Ilu< ValueType, ReverseApply, IndexType > && other )

Move-assigns an ILU preconditioner.

Preserves the executor, moves the solvers and parameters. Creates a clone of the solvers if they are on the wrong executor. The moved-from object is empty (0x0 with nullptr solvers and default parameters)

◆ parse()

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>

static parameters_type gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >::parse	(	const config::pnode &	config,
		const config::registry &	context,
		const config::type_descriptor &	td_for_child = `config::make_type_descriptor< value_type, index_type >()`
	)

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

Note: only support the following when using <ValueType, ValueType, ReverseApply, IndexType> not <LSolverType, USolverType, ReverseApply, IndexType> variants

◆ transpose()

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>

std::unique_ptr<LinOp> gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >::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/ilu.hpp

Classes

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Detailed Description

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32> class gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >

Constructor & Destructor Documentation

◆ Ilu() [1/2]

◆ Ilu() [2/2]

Member Function Documentation

◆ conj_transpose()

◆ get_l_solver()

◆ get_u_solver()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ parse()

◆ transpose()

template<typename ValueType = default_precision, bool ReverseApply = false, typename IndexType = int32>
class gko::preconditioner::Ilu< ValueType, ReverseApply, IndexType >