Dune Core Modules (2.9.0)

Dune::ParSSOR< M, X, Y, C > Class Template Reference

A parallel SSOR preconditioner. More...

#include <dune/istl/schwarz.hh>

Public Types

typedef M matrix_type
 The matrix type the preconditioner is for.
 
typedef X domain_type
 The domain type of the preconditioner.
 
typedef Y range_type
 The range type of the preconditioner.
 
typedef X::field_type field_type
 The field type of the preconditioner.
 
typedef C communication_type
 The type of the communication object.
 

Public Member Functions

 ParSSOR (const matrix_type &A, int n, field_type w, const communication_type &c)
 Constructor. More...
 
virtual void pre (X &x, Y &b)
 Prepare the preconditioner. More...
 
virtual void apply (X &v, const Y &d)
 Apply the precondtioner. More...
 
virtual void post (X &x)
 Clean up. More...
 
virtual SolverCategory::Category category () const
 Category of the preconditioner (see SolverCategory::Category)
 

Detailed Description

template<class M, class X, class Y, class C>
class Dune::ParSSOR< M, X, Y, C >

A parallel SSOR preconditioner.

Template Parameters
MThe type of the sequential matrix to use, e.g. BCRSMatrix or another matrix type fulfilling the matrix interface of ISTL.
XThe type of the sequential vector to use for the left hand side, e.g. BlockVector or another type fulfilling the ISTL vector interface.
YThe type of the sequential vector to use for the right hand side, e..g. BlockVector or another type fulfilling the ISTL vector interface.
CThe type of the communication object. This must either be OwnerOverlapCopyCommunication or a type implementing the same interface.

Constructor & Destructor Documentation

◆ ParSSOR()

template<class M , class X , class Y , class C >
Dune::ParSSOR< M, X, Y, C >::ParSSOR ( const matrix_type A,
int  n,
field_type  w,
const communication_type c 
)
inline

Constructor.

constructor gets all parameters to operate the prec.

Parameters
AThe matrix to operate on.
nThe number of iterations to perform.
wThe relaxation factor.
cThe communication object for syncing overlap and copy data points. (E.~g. OwnerOverlapCopyCommunication )

Member Function Documentation

◆ apply()

template<class M , class X , class Y , class C >
virtual void Dune::ParSSOR< M, X, Y, C >::apply ( X &  v,
const Y &  d 
)
inlinevirtual

Apply the precondtioner.

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< X, Y >.

References Dune::bsorb(), and Dune::bsorf().

◆ post()

template<class M , class X , class Y , class C >
virtual void Dune::ParSSOR< M, X, Y, C >::post ( X &  x)
inlinevirtual

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
xThe right hand side of the equation.

Implements Dune::Preconditioner< X, Y >.

◆ pre()

template<class M , class X , class Y , class C >
virtual void Dune::ParSSOR< M, X, Y, C >::pre ( X &  x,
Y &  b 
)
inlinevirtual

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 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:32
Parameters
xThe left hand side of the equation.
bThe right hand side of the equation.

Implements Dune::Preconditioner< X, Y >.


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