Reference documentation for deal.II version Git 0183d66 2014-10-17 10:54:07 +0200
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PreconditionIdentity Class Reference

#include <deal.II/lac/precondition.h>

Inheritance diagram for PreconditionIdentity:


struct  AdditionalData

Public Member Functions

template<class MATRIX >
void initialize (const MATRIX &matrix, const AdditionalData &additional_data=AdditionalData())
template<class VECTOR >
void vmult (VECTOR &, const VECTOR &) const
template<class VECTOR >
void Tvmult (VECTOR &, const VECTOR &) const
template<class VECTOR >
void vmult_add (VECTOR &, const VECTOR &) const
template<class VECTOR >
void Tvmult_add (VECTOR &, const VECTOR &) const
void clear ()
- Public Member Functions inherited from Subscriptor
 Subscriptor ()
 Subscriptor (const Subscriptor &)
virtual ~Subscriptor ()
Subscriptoroperator= (const Subscriptor &)
void subscribe (const char *identifier=0) const
void unsubscribe (const char *identifier=0) const
unsigned int n_subscriptions () const
void list_subscribers () const
 DeclException3 (ExcInUse, int, char *, std::string &,<< "Object of class "<< arg2<< " is still used by "<< arg1<< " other objects.\n"<< "(Additional information: "<< arg3<< ")\n"<< "Note the entry in the Frequently Asked Questions of "<< "deal.II (linked to from for "<< "more information on what this error means.")
 DeclException2 (ExcNoSubscriber, char *, char *,<< "No subscriber with identifier \""<< arg2<< "\" did subscribe to this object of class "<< arg1)
template<class Archive >
void serialize (Archive &ar, const unsigned int version)

Detailed Description

No preconditioning. This class helps you, if you want to use a linear solver without preconditioning. All solvers in LAC require a preconditioner. Therefore, you must use the identity provided here to avoid preconditioning. It can be used in the following way:

SolverControl solver_control (1000, 1e-12);
SolverCG<> cg (solver_control);
cg.solve (system_matrix, solution, system_rhs,

See the step-3 tutorial program for an example and additional explanations.

Alternatively, the IdentityMatrix class can be used to precondition in this way.

Guido Kanschat, 1999

Definition at line 72 of file precondition.h.

Member Function Documentation

template<class MATRIX >
void PreconditionIdentity::initialize ( const MATRIX matrix,
const AdditionalData additional_data = AdditionalData() 

The matrix argument is ignored and here just for compatibility with more complex preconditioners.

template<class VECTOR >
void PreconditionIdentity::vmult ( VECTOR &  ,
const VECTOR &   
) const

Apply preconditioner.

template<class VECTOR >
void PreconditionIdentity::Tvmult ( VECTOR &  ,
const VECTOR &   
) const

Apply transpose preconditioner. Since this is the identity, this function is the same as vmult().

template<class VECTOR >
void PreconditionIdentity::vmult_add ( VECTOR &  ,
const VECTOR &   
) const

Apply preconditioner, adding to the previous value.

template<class VECTOR >
void PreconditionIdentity::Tvmult_add ( VECTOR &  ,
const VECTOR &   
) const

Apply transpose preconditioner, adding. Since this is the identity, this function is the same as vmult_add().

void PreconditionIdentity::clear ( )

This function is only present to provide the interface of a preconditioner to be handed to a smoother. This does nothing.

Definition at line 141 of file precondition.h.

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