Dune::PDELab::SeqDGAMGPrec< DGMatrix, DGPrec, CGPrec, P > Class Template Reference

#include <dune/pdelab/backend/istl/seq_amg_dg_backend.hh>

Public Types
typedef DGPrec::domain_type	domain_type
	The domain type of the preconditioner.
typedef DGPrec::range_type	range_type
	The range type of the preconditioner.
typedef X::field_type	field_type
	The field type of the preconditioner.

Public Member Functions
SolverCategory::Category	category () const override
	Category of the preconditioner (see SolverCategory::Category)
	SeqDGAMGPrec (DGMatrix &dgmatrix_, DGPrec &dgprec_, CGPrec &cgprec_, P &p_, int n1_, int n2_)
	Constructor. More...
virtual void	pre (X &x, Y &b) override
	Prepare the preconditioner. More...
virtual void	apply (X &x, const Y &b) override
	Apply the precondioner. More...
virtual void	post (X &x) override
	Clean up. More...

Detailed Description

template<class DGMatrix, class DGPrec, class CGPrec, class P>
class Dune::PDELab::SeqDGAMGPrec< DGMatrix, DGPrec, CGPrec, P >

An ISTL preconditioner for DG based on AMG applied to CG subspace

The template parameters are: DGMatrix BCRSMatrix assembled with DG DGPrec preconditioner to be used for DG CGPrec preconditioner to be used on CG subspace P BCRSMatrix for grid transfer

Constructor & Destructor Documentation

SeqDGAMGPrec()

template<class DGMatrix , class DGPrec , class CGPrec , class P >

Dune::PDELab::SeqDGAMGPrec< DGMatrix, DGPrec, CGPrec, P >::SeqDGAMGPrec ( DGMatrix &  dgmatrix_, DGPrec &  dgprec_, CGPrec &  cgprec_, P &  p_, int  n1_, int  n2_  )

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 DGMatrix , class DGPrec , class CGPrec , class P >

virtual void Dune::PDELab::SeqDGAMGPrec< DGMatrix, DGPrec, CGPrec, P >::apply ( X &  x, const Y &  b  )

inlineoverridevirtual

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< DGPrec::domain_type, DGPrec::range_type >.

post()

template<class DGMatrix , class DGPrec , class CGPrec , class P >

virtual void Dune::PDELab::SeqDGAMGPrec< DGMatrix, DGPrec, CGPrec, P >::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< DGPrec::domain_type, DGPrec::range_type >.

pre()

template<class DGMatrix , class DGPrec , class CGPrec , class P >

virtual void Dune::PDELab::SeqDGAMGPrec< DGMatrix, DGPrec, CGPrec, P >::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< DGPrec::domain_type, DGPrec::range_type >.

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

• dune/pdelab/backend/istl/seq_amg_dg_backend.hh