Dune Core Modules (2.9.0)

Dune::InverseOperator2Preconditioner< O, c > Class Template Reference

Turns an InverseOperator into a Preconditioner. More...

#include <dune/istl/preconditioners.hh>

Public Types

typedef O::domain_type domain_type
 The domain type of the preconditioner.
 
typedef O::range_type range_type
 The range type of the preconditioner.
 
typedef range_type::field_type field_type
 The field type of the preconditioner.
 
typedef Simd::Scalar< field_typescalar_field_type
 scalar type underlying the field_type
 
typedef FieldTraits< scalar_field_type >::real_type real_field_type
 real scalar type underlying the field_type
 
typedef O InverseOperator
 type of the wrapped inverse operator
 

Public Member Functions

 InverseOperator2Preconditioner (InverseOperator &inverse_operator)
 Construct the preconditioner from the solver. More...
 
virtual void pre (domain_type &, range_type &)
 Prepare the preconditioner. More...
 
virtual void apply (domain_type &v, const range_type &d)
 Apply one step of the preconditioner to the system A(v)=d. More...
 
virtual void post (domain_type &)
 Clean up. More...
 
virtual SolverCategory::Category category () const
 Category of the preconditioner (see SolverCategory::Category)
 

Detailed Description

template<class O, int c = -1>
class Dune::InverseOperator2Preconditioner< O, c >

Turns an InverseOperator into a Preconditioner.

Template Parameters
OThe type of the inverse operator to wrap.

Constructor & Destructor Documentation

◆ InverseOperator2Preconditioner()

template<class O , int c = -1>
Dune::InverseOperator2Preconditioner< O, c >::InverseOperator2Preconditioner ( InverseOperator inverse_operator)
inline

Construct the preconditioner from the solver.

Parameters
inverse_operatorThe inverse operator to wrap.

References Dune::SolverCategory::category(), and DUNE_THROW.

Member Function Documentation

◆ apply()

template<class O , int c = -1>
virtual void Dune::InverseOperator2Preconditioner< O, c >::apply ( domain_type v,
const range_type d 
)
inlinevirtual

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]vThe update to be computed
dThe current defect.

Implements Dune::Preconditioner< O::domain_type, O::range_type >.

◆ post()

template<class O , int c = -1>
virtual void Dune::InverseOperator2Preconditioner< O, c >::post ( domain_type 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
xThe right hand side of the equation.

Implements Dune::Preconditioner< O::domain_type, O::range_type >.

◆ pre()

template<class O , int c = -1>
virtual void Dune::InverseOperator2Preconditioner< O, c >::pre ( domain_type x,
range_type 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
Parameters
xThe left hand side of the equation.
bThe right hand side of the equation.

Implements Dune::Preconditioner< O::domain_type, O::range_type >.


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