The sequential jacobian 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
	SeqJac (const M &A, int n, scalar_field_type w)
	Constructor. More...

	SeqJac (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...

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::SeqJac< M, X, Y, l >

The sequential jacobian preconditioner.

Wraps the naked ISTL generic block Jacobi 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

◆ SeqJac() [1/2]

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

Dune::SeqJac< M, X, Y, l >::SeqJac	(	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.

◆ SeqJac() [2/2]

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

Dune::SeqJac< M, X, Y, l >::SeqJac	(	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()

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

virtual void Dune::SeqJac< 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 >.

References Dune::dbjac().

◆ post()

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

virtual void Dune::SeqJac< 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::SeqJac< 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