Dune::PDELab::GridOperatorPreconditioner< PrecGO > Class Template Reference

Turn a grid operator that represents a preconditioner into an ISTL preconditioner. More...

#include <dune/pdelab/backend/istl/matrixfree/gridoperatorpreconditioner.hh>

Public Types
typedef PrecGO::Traits::Domain	domain_type
	The domain type of the preconditioner.
typedef PrecGO::Traits::Range	range_type
	The range type of the preconditioner.
typedef X::field_type	field_type
	The field type of the preconditioner.

Public Member Functions
Dune::SolverCategory::Category	category () const override
	Category of the preconditioner (see SolverCategory::Category)
void	setLinearizationPoint (const Domain &u)
void	pre (Domain &v, Range &d) override
	prepare preconditioner
void	post (Domain &v) override
	Clean up. More...
virtual void	pre (PrecGO::Traits::Domain &x, PrecGO::Traits::Range &b)=0
	Prepare the preconditioner. More...
virtual void	apply (PrecGO::Traits::Domain &v, const PrecGO::Traits::Range &d)=0
	Apply one step of the preconditioner to the system A(v)=d. More...

Detailed Description

template<class PrecGO>
class Dune::PDELab::GridOperatorPreconditioner< PrecGO >

Turn a grid operator that represents a preconditioner into an ISTL preconditioner.

Template Parameters

PrecGO

Grid operator implementing the matrix-free preconditioner application

Member Function Documentation

apply()

virtual void Dune::Preconditioner< PrecGO::Traits::Domain , PrecGO::Traits::Range >::apply ( PrecGO::Traits::Domain &  v, const PrecGO::Traits::Range &  d  )

pure virtualinherited

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.

post()

template<class PrecGO >

void Dune::PDELab::GridOperatorPreconditioner< PrecGO >::post ( Domain &  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< PrecGO::Traits::Domain, PrecGO::Traits::Range >.

pre()

virtual void Dune::Preconditioner< PrecGO::Traits::Domain , PrecGO::Traits::Range >::pre ( PrecGO::Traits::Domain &  x, PrecGO::Traits::Range &  b  )

pure virtualinherited

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.

setLinearizationPoint()

template<class PrecGO >

void Dune::PDELab::GridOperatorPreconditioner< PrecGO >::setLinearizationPoint ( const Domain &  u )

inline

Set linearization point Must be called before apply() for nonlinear problems.

Referenced by Dune::PDELab::ISTLBackend_SEQ_MatrixFree_Base< GO, PrecGO, Solver >::setLinearizationPoint().

---

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

• dune/pdelab/backend/istl/matrixfree/gridoperatorpreconditioner.hh