Sequential ILU(n) preconditioner. More...

#include <dune/istl/preconditioners.hh>

Public Types
enum	{ category =SolverCategory::sequential }

typedef Dune::remove_const< M >::type	matrix_type
	The matrix type the preconditioner is for.

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.

Public Member Functions
	SeqILUn (const M &A, int n, field_type w)
	Constructor. More...

virtual void	pre (X &x, Y &b)
	Prepare the preconditioner. More...

virtual void	apply (X &v, const Y &d)
	Apply the precondioner. More...

virtual void	post (X &x)
	Clean up. More...

Detailed Description

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

Sequential ILU(n) preconditioner.

Wraps the naked ISTL generic ILU(n) 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.

Member Enumeration Documentation

◆ anonymous enum

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

anonymous enum

Enumerator
category	The category the preconditioner is part of.

Constructor & Destructor Documentation

◆ SeqILUn()

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

Dune::SeqILUn< M, X, Y, l >::SeqILUn	(	const M &	A,
		int	n,
		field_type	w
	)

inline

Constructor.

Constructor gets all parameters to operate the prec.

Parameters

A	The matrix to operate on.
n	The number of iterations to perform.
w	The relaxation factor.

Member Function Documentation

◆ apply()

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

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

inlinevirtual

Apply the precondioner.

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::bilu_backsolve().

◆ post()

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

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

inlinevirtual

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 >.

References DUNE_UNUSED_PARAMETER.

◆ pre()

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

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

inlinevirtual

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.

Parameters