A parallel SSOR preconditioner. More...

#include <dune/istl/schwarz.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 C	communication_type
	The type of the communication object.

Public Member Functions
	ParSSOR (const matrix_type &A, int n, field_type w, const communication_type &c)
	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)

Detailed Description

template<class M, class X, class Y, class C>
class Dune::ParSSOR< M, X, Y, C >

A parallel SSOR preconditioner.

Template Parameters

M	The type of the sequential matrix to use, e.g. BCRSMatrix or another matrix type fulfilling the matrix interface of ISTL.
X	The type of the sequential vector to use for the left hand side, e.g. BlockVector or another type fulfilling the ISTL vector interface.
Y	The type of the sequential vector to use for the right hand side, e..g. BlockVector or another type fulfilling the ISTL vector interface.
C	The type of the communication object. This must either be OwnerOverlapCopyCommunication or a type implementing the same interface.

Constructor & Destructor Documentation

◆ ParSSOR()

template<class M , class X , class Y , class C >

Dune::ParSSOR< M, X, Y, C >::ParSSOR	(	const matrix_type &	A,
		int	n,
		field_type	w,
		const communication_type &	c
	)

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.
c	The communication object for syncing overlap and copy data points. (E.~g. OwnerOverlapCopyCommunication )

Member Function Documentation

◆ apply()

template<class M , class X , class Y , class C >

void Dune::ParSSOR< M, X, Y, C >::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::bsorb(), and Dune::bsorf().

◆ post()

template<class M , class X , class Y , class C >

void Dune::ParSSOR< M, X, Y, C >::post ( X & x )

inlineoverridevirtual

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 , class C >

void Dune::ParSSOR< M, X, Y, C >::pre	(	X &	x,
		Y &	b
	)

inlineoverridevirtual

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