Dune Core Modules (2.9.0)

Sequential ILU preconditioner. More...

#include <dune/istl/preconditioners.hh>

Public Types

typedef std::remove_const< M >::type matrix_type
 The matrix type the preconditioner is for.
 
typedef matrix_type::block_type block_type
 block type of matrix
 
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 Simd::Scalar< field_typescalar_field_type
 scalar type underlying the field_type
 
typedef FieldTraits< scalar_field_type >::real_type real_field_type
 real scalar type underlying the field_type
 
typedef ILU::CRS< block_type, typename M::allocator_type > CRS
 type of ILU storage
 

Public Member Functions

 SeqILU (const M &A, real_field_type w, const bool resort=false)
 Constructor. More...
 
 SeqILU (const std::shared_ptr< const AssembledLinearOperator< M, X, Y > > &A, const ParameterTree &configuration)
 Constructor. More...
 
 SeqILU (const M &A, const ParameterTree &config)
 Constructor. More...
 
 SeqILU (const M &A, int n, real_field_type w, const bool resort=false)
 Constructor. More...
 
virtual void pre (X &x, Y &b)
 Prepare the preconditioner. More...
 
virtual void apply (X &v, const Y &d)
 Apply the preconditioner. More...
 
virtual void post (X &x)
 Clean up. More...
 
virtual SolverCategory::Category category () const
 Category of the preconditioner (see SolverCategory::Category)
 

Protected Attributes

std::unique_ptr< matrix_typeILU_
 The ILU(n) decomposition of the matrix. As storage a BCRSMatrix is used.
 
CRS lower_
 The ILU(n) decomposition of the matrix. As storage a CRS structure is used.
 
const real_field_type w_
 The relaxation factor to use.
 
const bool wNotIdentity_
 true if w != 1.0
 

Detailed Description

template<class M, class X, class Y, int l = 1>
class Dune::SeqILU< M, X, Y, l >

Sequential ILU preconditioner.

Wraps the naked ISTL generic ILU preconditioner into the solver framework.

Template Parameters
MThe matrix type to operate on
XType of the update
YType of the defect
lIgnored. Just there to have the same number of template arguments as other preconditioners.

Constructor & Destructor Documentation

◆ SeqILU() [1/4]

template<class M , class X , class Y , int l = 1>
Dune::SeqILU< M, X, Y, l >::SeqILU ( const M &  A,
real_field_type  w,
const bool  resort = false 
)
inline

Constructor.

Constructor invoking ILU(0) gets all parameters to operate the prec.

Parameters
AThe matrix to operate on.
wThe relaxation factor.
resorttrue if a resort of the computed ILU for improved performance should be done.

◆ SeqILU() [2/4]

template<class M , class X , class Y , int l = 1>
Dune::SeqILU< M, X, Y, l >::SeqILU ( const std::shared_ptr< const AssembledLinearOperator< M, X, Y > > &  A,
const ParameterTree configuration 
)
inline

Constructor.

Parameters
AThe assembled linear operator to use.
configurationParameterTree containing preconditioner parameters.
ParameterTree Key Meaning
n The order of the ILU decomposition. default=0
relaxation The relaxation factor. default=1.0
resort True if a resort of the computed ILU for improved performance should be done. default=false

See ISTL_Factory for the ParameterTree layout and examples.

◆ SeqILU() [3/4]

template<class M , class X , class Y , int l = 1>
Dune::SeqILU< M, X, Y, l >::SeqILU ( const M &  A,
const ParameterTree config 
)
inline

Constructor.

Parameters
AThe matrix to operate on.
configurationParameterTree containing preconditioner parameters.
ParameterTree Key Meaning
n The order of the ILU decomposition. default=0
relaxation The relaxation factor. default=1.0
resort True if a resort of the computed ILU for improved performance should be done. default=false

See ISTL_Factory for the ParameterTree layout and examples.

◆ SeqILU() [4/4]

template<class M , class X , class Y , int l = 1>
Dune::SeqILU< M, X, Y, l >::SeqILU ( const M &  A,
int  n,
real_field_type  w,
const bool  resort = false 
)
inline

Constructor.

Constructor invoking ILU(n).

Parameters
AThe matrix to operate on.
nThe order of the ILU decomposition.
wThe relaxation factor.
resorttrue if a resort of the computed ILU for improved performance should be done.

Member Function Documentation

◆ apply()

template<class M , class X , class Y , int l = 1>
virtual void Dune::SeqILU< M, X, Y, l >::apply ( X &  v,
const Y &  d 
)
inlinevirtual

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]vThe update to be computed
dThe current defect.

Implements Dune::Preconditioner< X, Y >.

◆ post()

template<class M , class X , class Y , int l = 1>
virtual void Dune::SeqILU< M, X, Y, l >::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 , int l = 1>
virtual void Dune::SeqILU< M, X, Y, l >::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 >.


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