Sequential SOR preconditioner. More...

#include <dune/istl/preconditioners.hh>

Public Types
typedef M	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.

typedef Simd::Scalar< field_type >	scalar_field_type
	scalar type underlying the field_type

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

	SeqSOR (const M &A, const ParameterTree &configuration)
	Constructor. More...

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

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

template<bool forward>
void	apply (X &v, const Y &d)
	Apply the preconditioner in a special direction. More...

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

virtual SolverCategory::Category	category () const
	Category of the preconditioner (see SolverCategory::Category)

Detailed Description

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

Sequential SOR preconditioner.

Wraps the naked ISTL generic SOR 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	The block level to invert. Default is 1

Constructor & Destructor Documentation

◆ SeqSOR() [1/2]

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

Dune::SeqSOR< M, X, Y, l >::SeqSOR	(	const M &	A,
		int	n,
		scalar_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.

◆ SeqSOR() [2/2]

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

Dune::SeqSOR< M, X, Y, l >::SeqSOR	(	const M &	A,
		const ParameterTree &	configuration
	)

inline

Constructor.

Parameters

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

ParameterTree Key	Meaning
iterations	The number of iterations to perform. default=1
relaxation	The relaxation factor

See ISTL_Factory for the ParameterTree layout and examples.

Member Function Documentation

◆ apply() [1/2]

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

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

inlinevirtual

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 >.

◆ apply() [2/2]

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

template<bool forward>

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

inlinevirtual

Apply the preconditioner in a special direction.

The template parameter forward indications the direction the smoother is applied. If true The application is started at the lowest index in the vector v, if false at the highest index of vector v.

Implements Dune::Preconditioner< X, Y >.

References Dune::bsorb(), and Dune::bsorf().

◆ post()

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

virtual void Dune::SeqSOR< 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::SeqSOR< 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.

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

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