Dune::SeqILU< M, X, Y, l > Class Template Reference

Sequential ILU preconditioner. More...

#include <dune/istl/preconditioners.hh>

Public Types
typedef std::remove_const< M >::type	matrix_type
	The matrix type the preconditioner is for.
typedef matrix_type::block_type	block_type
	block type of matrix
typedef X	domain_type
	The domain type of the preconditioner.
typedef Y	range_type
	The range type of the preconditioner.
typedef X::field_type	field_type
	The field type of the preconditioner.
typedef Simd::Scalar< field_type >	scalar_field_type
	scalar type underlying the field_type
typedef FieldTraits< scalar_field_type >::real_type	real_field_type
	real scalar type underlying the field_type
typedef ILU::CRS< block_type, typename M::allocator_type >	CRS
	type of ILU storage

Public Member Functions
	SeqILU (const M &A, real_field_type w, const bool resort=false)
	Constructor. More...
	SeqILU (const std::shared_ptr< const AssembledLinearOperator< M, X, Y > > &A, const ParameterTree &configuration)
	Constructor. More...
	SeqILU (const M &A, const ParameterTree &config)
	Constructor. More...
	SeqILU (const M &A, int n, real_field_type w, const bool resort=false)
	Constructor. More...
void	pre (X &x, Y &b) override
	Prepare the preconditioner. More...
void	apply (X &v, const Y &d) override
	Apply the preconditioner. More...
void	post (X &x) override
	Clean up. More...
SolverCategory::Category	category () const override
	Category of the preconditioner (see SolverCategory::Category)

Protected Attributes
std::unique_ptr< matrix_type >	ILU_
	The ILU(n) decomposition of the matrix. As storage a BCRSMatrix is used.
CRS	lower_
	The ILU(n) decomposition of the matrix. As storage a CRS structure is used.
const real_field_type	w_
	The relaxation factor to use.
const bool	wNotIdentity_
	true if w != 1.0

Detailed Description

template<class M, class X, class Y, int l = 1>
class Dune::SeqILU< M, X, Y, l >

Sequential ILU preconditioner.

Wraps the naked ISTL generic ILU preconditioner into the solver framework.

Template Parameters

M	The matrix type to operate on
X	Type of the update
Y	Type of the defect
l	Ignored. Just there to have the same number of template arguments as other preconditioners.

Constructor & Destructor Documentation

SeqILU() [1/4]

template<class M , class X , class Y , int l = 1>

Dune::SeqILU< M, X, Y, l >::SeqILU ( const M &  A, real_field_type  w, const bool  resort = false  )

inline

Constructor.

Constructor invoking ILU(0) gets all parameters to operate the prec.

Parameters

A	The matrix to operate on.
w	The relaxation factor.
resort	true if a resort of the computed ILU for improved performance should be done.

SeqILU() [2/4]

template<class M , class X , class Y , int l = 1>

Dune::SeqILU< M, X, Y, l >::SeqILU ( const std::shared_ptr< const AssembledLinearOperator< M, X, Y > > &  A, const ParameterTree &  configuration  )

inline

Constructor.

Parameters

A	The assembled linear operator to use.
configuration	ParameterTree containing preconditioner parameters.

ParameterTree Key	Meaning
n	The order of the ILU decomposition. default=0
relaxation	The relaxation factor. default=1.0
resort	True if a resort of the computed ILU for improved performance should be done. default=false

See ISTL_Factory for the ParameterTree layout and examples.

SeqILU() [3/4]

template<class M , class X , class Y , int l = 1>

Dune::SeqILU< M, X, Y, l >::SeqILU ( const M &  A, const ParameterTree &  config  )

inline

Constructor.

Parameters

A	The matrix to operate on.
config	ParameterTree containing preconditioner parameters.

ParameterTree Key	Meaning
n	The order of the ILU decomposition. default=0
relaxation	The relaxation factor. default=1.0
resort	True if a resort of the computed ILU for improved performance should be done. default=false

See ISTL_Factory for the ParameterTree layout and examples.

SeqILU() [4/4]

template<class M , class X , class Y , int l = 1>

Dune::SeqILU< M, X, Y, l >::SeqILU ( const M &  A, int  n, real_field_type  w, const bool  resort = false  )

inline

Constructor.

Constructor invoking ILU(n).

Parameters

A	The matrix to operate on.
n	The order of the ILU decomposition.
w	The relaxation factor.
resort	true if a resort of the computed ILU for improved performance should be done.

Member Function Documentation

apply()

template<class M , class X , class Y , int l = 1>

void Dune::SeqILU< M, X, Y, l >::apply ( X &  v, const Y &  d  )

inlineoverridevirtual

Apply the preconditioner.

Apply one step of the preconditioner to the system A(v)=d.

On entry v=0 and d=b-A(x) (although this might not be computed in that way. On exit v contains the update, i.e one step computes \( v = M^{-1} d \) where \( M \) is the approximate inverse of the operator \( A \) characterizing the preconditioner.

Parameters

[out]	v	The update to be computed
	d	The current defect.

Implements Dune::Preconditioner< X, Y >.

References Dune::SeqILU< M, X, Y, l >::ILU_, Dune::SeqILU< M, X, Y, l >::lower_, Dune::SeqILU< M, X, Y, l >::w_, and Dune::SeqILU< M, X, Y, l >::wNotIdentity_.

post()

template<class M , class X , class Y , int l = 1>

void Dune::SeqILU< M, X, Y, l >::post ( X &  x )

inlineoverridevirtual

Clean up.

Clean up.

This method is called after the last apply call for the linear system to be solved. Memory may be deallocated safely here. x is the solution of the linear equation.

Parameters

x	The right hand side of the equation.

Implements Dune::Preconditioner< X, Y >.

pre()

template<class M , class X , class Y , int l = 1>

void Dune::SeqILU< M, X, Y, l >::pre ( X &  x, Y &  b  )

inlineoverridevirtual

Prepare the preconditioner.

Prepare the preconditioner.

A solver solves a linear operator equation A(x)=b by applying one or several steps of the preconditioner. The method pre() is called before the first apply operation. b and x are right hand side and solution vector of the linear system respectively. It may. e.g., scale the system, allocate memory or compute a (I)LU decomposition. Note: The ILU decomposition could also be computed in the constructor or with a separate method of the derived method if several linear systems with the same matrix are to be solved.

Note

if a preconditioner is copied (e.g. for a second thread) again the pre() method has to be called to ensure proper memory management.

X x(0.0);
Y b = ...; // rhs
Preconditioner<X,Y> prec(...);
prec.pre(x,b);   // prepare the preconditioner
prec.apply(x,b); // can be called multiple times now...
prec.post(x);    // cleanup internal state

Parameters

x	The left hand side of the equation.
b	The right hand side of the equation.

Implements Dune::Preconditioner< X, Y >.

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

• dune/istl/preconditioners.hh