Dune Core Modules (2.9.0)
Base class for matrix free definition of preconditioners. More...
#include <dune/istl/preconditioner.hh>
Public Member Functions  
virtual void  pre (X &x, Y &b)=0 
Prepare the preconditioner. More...  
virtual void  apply (X &v, const Y &d)=0 
Apply one step of the preconditioner to the system A(v)=d. More...  
virtual void  post (X &x)=0 
Clean up. More...  
virtual SolverCategory::Category  category () const =0 
Category of the preconditioner (see SolverCategory::Category)  
virtual  ~Preconditioner () 
every abstract base class has a virtual destructor  
Detailed Description
class Dune::Preconditioner< X, Y >
Base class for matrix free definition of preconditioners.
Note that the operator, which is the basis for the preconditioning, is supplied to the preconditioner from the outside in the constructor or some other method.
This interface allows the encapsulation of all parallelization aspects into the preconditioners.
 Template Parameters

X Type of the update Y Type of the defect
Member Function Documentation
◆ apply()

pure virtual 
Apply one step of the preconditioner to the system A(v)=d.
On entry v=0 and d=bA(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.
Implemented in Dune::Amg::AMG< M, X, S, PI, A >, Dune::Amg::AMG< M, X, S, SequentialInformation, std::allocator< X > >, Dune::Amg::AMG< Operator, X, Smoother >, Dune::Amg::FastAMG< M, X, PI, A >, Dune::Amg::KAMG< M, X, S, PI, K, A >, Dune::NonoverlappingBlockPreconditioner< C, P >, Dune::InverseOperator2Preconditioner< O, c >, Dune::SeqOverlappingSchwarz< M, X, TM, TD, TA >, Dune::SeqOverlappingSchwarz< M, X, TM, TS, TA >, Dune::SeqOverlappingSchwarz< M, X, TM, TD, TA >, Dune::SeqOverlappingSchwarz< M, X, TM, TS, TA >, Dune::NonoverlappingBlockPreconditioner< C, P >, Dune::SeqSSOR< M, X, Y, l >, Dune::SeqSOR< M, X, Y, l >, Dune::SeqSOR< M, X, Y, l >, Dune::SeqJac< M, X, Y, l >, Dune::SeqILU< M, X, Y, l >, Dune::Richardson< X, Y >, Dune::ParSSOR< M, X, Y, C >, Dune::BlockPreconditioner< X, Y, C, P >, Dune::BlockPreconditioner< X, Y, C, P >, and Dune::SeqILDL< M, X, Y >.
◆ post()

pure virtual 
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.
Implemented in Dune::Amg::AMG< M, X, S, PI, A >, Dune::Amg::AMG< M, X, S, SequentialInformation, std::allocator< X > >, Dune::Amg::AMG< Operator, X, Smoother >, Dune::Amg::FastAMG< M, X, PI, A >, Dune::Amg::KAMG< M, X, S, PI, K, A >, Dune::InverseOperator2Preconditioner< O, c >, Dune::NonoverlappingBlockPreconditioner< C, P >, Dune::SeqOverlappingSchwarz< M, X, TM, TD, TA >, Dune::SeqOverlappingSchwarz< M, X, TM, TS, TA >, Dune::SeqSSOR< M, X, Y, l >, Dune::SeqSOR< M, X, Y, l >, Dune::SeqJac< M, X, Y, l >, Dune::SeqILU< M, X, Y, l >, Dune::Richardson< X, Y >, Dune::ParSSOR< M, X, Y, C >, Dune::BlockPreconditioner< X, Y, C, P >, and Dune::SeqILDL< M, X, Y >.
◆ pre()

pure virtual 
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.
 Parameters

x The left hand side of the equation. b The right hand side of the equation.
Implemented in Dune::Amg::AMG< M, X, S, PI, A >, Dune::Amg::AMG< M, X, S, SequentialInformation, std::allocator< X > >, Dune::Amg::AMG< Operator, X, Smoother >, Dune::Amg::FastAMG< M, X, PI, A >, Dune::Amg::KAMG< M, X, S, PI, K, A >, Dune::InverseOperator2Preconditioner< O, c >, Dune::NonoverlappingBlockPreconditioner< C, P >, Dune::SeqOverlappingSchwarz< M, X, TM, TD, TA >, Dune::SeqOverlappingSchwarz< M, X, TM, TS, TA >, Dune::SeqSSOR< M, X, Y, l >, Dune::SeqSOR< M, X, Y, l >, Dune::SeqJac< M, X, Y, l >, Dune::SeqILU< M, X, Y, l >, Dune::Richardson< X, Y >, Dune::ParSSOR< M, X, Y, C >, Dune::BlockPreconditioner< X, Y, C, P >, and Dune::SeqILDL< M, X, Y >.
The documentation for this class was generated from the following file:
 dune/istl/preconditioner.hh