DUNE PDELab (2.8)

Dune::Amg::TwoLevelMethod< FO, CSP, S > Class Template Referenceabstract

#include <dune/istl/paamg/twolevelmethod.hh>

Public Types

typedef CSP CoarseLevelSolverPolicy
 The type of the policy for constructing the coarse level solver.
 
typedef CoarseLevelSolverPolicy::CoarseLevelSolver CoarseLevelSolver
 The type of the coarse level solver.
 
typedef FO FineOperatorType
 The linear operator of the finel level system. Has to be derived from AssembledLinearOperator.
 
typedef FineOperatorType::range_type FineRangeType
 The type of the range of the fine level operator.
 
typedef FineOperatorType::domain_type FineDomainType
 The type of the domain of the fine level operator.
 
typedef CSP::Operator CoarseOperatorType
 The linear operator of the finel level system. Has to be derived from AssembledLinearOperator.
 
typedef CoarseOperatorType::range_type CoarseRangeType
 The type of the range of the coarse level operator.
 
typedef CoarseOperatorType::domain_type CoarseDomainType
 The type of the domain of the coarse level operator.
 
typedef S SmootherType
 The type of the fine level smoother.
 
typedef FO::domain_type domain_type
 The domain type of the preconditioner.
 
typedef FO::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

 TwoLevelMethod (const FineOperatorType &op, std::shared_ptr< SmootherType > smoother, const LevelTransferPolicy< FineOperatorType, CoarseOperatorType > &policy, CoarseLevelSolverPolicy &coarsePolicy, std::size_t preSteps=1, std::size_t postSteps=1)
 Constructs a two level method. More...
 
virtual SolverCategory::Category category () const
 Category of the preconditioner (see SolverCategory::Category)
 
virtual void pre (FO::domain_type &x, FO::range_type &b)=0
 Prepare the preconditioner. More...
 
virtual void apply (FO::domain_type &v, const FO::range_type &d)=0
 Apply one step of the preconditioner to the system A(v)=d. More...
 
virtual void post (FO::domain_type &x)=0
 Clean up. More...
 

Detailed Description

template<class FO, class CSP, class S>
class Dune::Amg::TwoLevelMethod< FO, CSP, S >
Template Parameters
FOThe type of the fine level linear operator.
CSPThe type of the coarse level solver policy.
SThe type of the fine level smoother used.

Constructor & Destructor Documentation

◆ TwoLevelMethod()

template<class FO , class CSP , class S >
Dune::Amg::TwoLevelMethod< FO, CSP, S >::TwoLevelMethod ( const FineOperatorType op,
std::shared_ptr< SmootherType smoother,
const LevelTransferPolicy< FineOperatorType, CoarseOperatorType > &  policy,
CoarseLevelSolverPolicy coarsePolicy,
std::size_t  preSteps = 1,
std::size_t  postSteps = 1 
)
inline

Constructs a two level method.

Template Parameters
CoarseSolverPolicyThe policy for constructing the coarse solver, e.g. OneStepAMGCoarseSolverPolicy
Parameters
opThe fine level operator.
smootherThe fine level smoother.
policyThe level transfer policy.
coarsePolicyThe policy for constructing the coarse level solver.
preStepsThe number of smoothing steps to apply before the coarse level correction.
preStepsThe number of smoothing steps to apply after the coarse level correction.

References Dune::Amg::LevelTransferPolicy< FO, CO >::clone(), and Dune::Amg::LevelTransferPolicy< FO, CO >::createCoarseLevelSystem().

Member Function Documentation

◆ apply()

virtual void Dune::Preconditioner< FO::domain_type , FO::range_type >::apply ( FO::domain_type &  v,
const FO::range_type &  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]vThe update to be computed
dThe current defect.

◆ post()

virtual void Dune::Preconditioner< FO::domain_type , FO::range_type >::post ( FO::domain_type &  x)
pure virtualinherited

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.

◆ pre()

virtual void Dune::Preconditioner< FO::domain_type , FO::range_type >::pre ( FO::domain_type &  x,
FO::range_type &  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 mangement.
X x(0.0);
Y b = ...; // rhs
prec.pre(x,b); // prepare the preconditioner
prec.apply(x,b); // can be called multiple times now...
prec.post(x); // cleanup internal state
Base class for matrix free definition of preconditioners.
Definition: preconditioner.hh:30
Parameters
xThe left hand side of the equation.
bThe right hand side of the equation.

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