Dune::BlockPreconditioner< X, Y, C, P > Class Template Reference

Block parallel preconditioner. More...

#include <dune/istl/schwarz.hh>

Public Types
typedef X	domain_type
	The domain type of the preconditioner. More...
typedef Y	range_type
	The range type of the preconditioner. More...
typedef X::field_type	field_type
	The field type of the preconditioner.
typedef C	communication_type
	The type of the communication object.. More...

Public Member Functions
	BlockPreconditioner (P &p, const communication_type &c)
	Constructor. More...
	BlockPreconditioner (const std::shared_ptr< P > &p, const communication_type &c)
	Constructor. More...
void	pre (X &x, Y &b) override
	Prepare the preconditioner. More...
void	apply (X &v, const Y &d) override
	Apply the preconditioner. More...
template<bool forward>
void	apply (X &v, const Y &d)
	Apply one step of the preconditioner to the system A(v)=d. More...
void	post (X &x) override
	Clean up. More...
SolverCategory::Category	category () const override
	Category of the preconditioner (see SolverCategory::Category)

Detailed Description

template<class X, class Y, class C, class P = Preconditioner<X,Y>>
class Dune::BlockPreconditioner< X, Y, C, P >

Block parallel preconditioner.

This is essentially a wrapper that takes a sequential preconditioner. In each step the sequential preconditioner is applied and then all owner data points are updated on all other processes.

Template Parameters

M	The type of the sequential matrix to use, e.g. BCRSMatrix or another matrix type fulfilling the matrix interface of ISTL.
X	The type of the sequential vector to use for the left hand side, e.g. BlockVector or another type fulfilling the ISTL vector interface.
Y	The type of the sequential vector to use for the right hand side, e..g. BlockVector or another type fulfilling the ISTL vector interface.
C	The type of the communication object. This must either be OwnerOverlapCopyCommunication or a type implementing the same interface.
The	type of the sequential preconditioner to use for approximately solving the local matrix block consisting of unknowns owned by the process. Has to implement the Preconditioner interface.

Member Typedef Documentation

communication_type

template<class X , class Y , class C , class P = Preconditioner<X,Y>>

typedef C Dune::BlockPreconditioner< X, Y, C, P >::communication_type

The type of the communication object..

This must either be OwnerOverlapCopyCommunication or a type implementing the same interface.

domain_type

template<class X , class Y , class C , class P = Preconditioner<X,Y>>

typedef X Dune::BlockPreconditioner< X, Y, C, P >::domain_type

The domain type of the preconditioner.

E.g. BlockVector or another type fulfilling the ISTL vector interface.

range_type

template<class X , class Y , class C , class P = Preconditioner<X,Y>>

typedef Y Dune::BlockPreconditioner< X, Y, C, P >::range_type

The range type of the preconditioner.

E.g. BlockVector or another type fulfilling the ISTL vector interface.

Constructor & Destructor Documentation

BlockPreconditioner() [1/2]

template<class X , class Y , class C , class P = Preconditioner<X,Y>>

Dune::BlockPreconditioner< X, Y, C, P >::BlockPreconditioner ( P &  p, const communication_type &  c  )

inline

Constructor.

constructor gets all parameters to operate the prec.

Parameters

p	The sequential preconditioner.
c	The communication object for syncing overlap and copy data points. (E.~g. OwnerOverlapCopyCommunication )

BlockPreconditioner() [2/2]

template<class X , class Y , class C , class P = Preconditioner<X,Y>>

Dune::BlockPreconditioner< X, Y, C, P >::BlockPreconditioner ( const std::shared_ptr< P > &  p, const communication_type &  c  )

inline

Constructor.

constructor gets all parameters to operate the prec.

Parameters

p	The sequential preconditioner.
c	The communication object for syncing overlap and copy data points. (E.~g. OwnerOverlapCopyCommunication )

Member Function Documentation

apply() [1/2]

template<class X , class Y , class C , class P = Preconditioner<X,Y>>

template<bool forward>

void Dune::BlockPreconditioner< X, Y, C, P >::apply ( X &  v, const Y &  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]	v	The update to be computed
	d	The current defect.

Implements Dune::Preconditioner< X, Y >.

apply() [2/2]

template<class X , class Y , class C , class P = Preconditioner<X,Y>>

void Dune::BlockPreconditioner< X, Y, C, P >::apply ( X &  v, const Y &  d  )

inlineoverridevirtual

Apply the preconditioner.

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.

Implements Dune::Preconditioner< X, Y >.

post()

template<class X , class Y , class C , class P = Preconditioner<X,Y>>

void Dune::BlockPreconditioner< X, Y, C, P >::post ( X &  x )

inlineoverridevirtual

Clean up.

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< X, Y >.

pre()

template<class X , class Y , class C , class P = Preconditioner<X,Y>>

void Dune::BlockPreconditioner< X, Y, C, P >::pre ( X &  x, Y &  b  )

inlineoverridevirtual

Prepare the preconditioner.

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.

Implements Dune::Preconditioner< X, Y >.

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

• dune/istl/schwarz.hh