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// $Id: precondition_selector.h 31932 2013-12-08 02:15:54Z heister $
//
// Copyright (C) 1999 - 2013 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, redistribute
// it, and/or modify it under the terms of the GNU Lesser General
// Public License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// The full text of the license can be found in the file LICENSE at
// the top level of the deal.II distribution.
//
// ---------------------------------------------------------------------
#ifndef __deal2__precondition_selector_h
#define __deal2__precondition_selector_h
#include <deal.II/base/config.h>
#include <deal.II/base/smartpointer.h>
#include <string>
DEAL_II_NAMESPACE_OPEN
template <class number> class Vector;
template <class number> class SparseMatrix;
/*! @addtogroup Preconditioners
*@{
*/
/**
* Selects the preconditioner. The constructor of this class takes
* the name of the preconditioning and the damping parameter
* @p omega of the preconditioning and the @p use_matrix function takes
* the matrix that is used
* by the matrix-builtin precondition functions. Each time, the <tt>operator()</tt> function
* is called, this preselected preconditioner, this matrix and
* this @p omega is used
* for the preconditioning. This class is designed for being used as
* argument of the @p solve function of a @p Solver and it covers the
* selection of all matrix-builtin precondition functions. The selection
* of other preconditioners, like BlockSOR or ILU should be handled in
* derived classes by the user.
*
* <h3>Usage</h3>
* The simplest use of this class is the following:
* @code
* // generate a @p SolverControl and
* // a @p VectorMemory
* SolverControl control;
* VectorMemory<Vector<double> > memory;
* // generate a solver
* SolverCG<SparseMatrix<double>, Vector<double> > solver(control, memory);
* // generate a @p PreconditionSelector
* PreconditionSelector<SparseMatrix<double>, Vector<double> >
* preconditioning("jacobi", 1.);
* // give a matrix whose diagonal entries
* // are to be used for the preconditioning.
* // Generally the matrix of the linear
* // equation system Ax=b.
* preconditioning.use_matrix(A);
* // call the @p solve function with this
* // preconditioning as last argument
* solver.solve(A,x,b,preconditioning);
* @endcode
* The same example where also the @p SolverSelector class is used reads
* @code
* // generate a @p SolverControl and
* // a @p VectorMemory
* SolverControl control;
* VectorMemory<Vector<double> > memory;
* // generate a @p SolverSelector that
* // calls the @p SolverCG
* SolverSelector<SparseMatrix<double>, Vector<double> >
* solver_selector("cg", control, memory);
* // generate a @p PreconditionSelector
* PreconditionSelector<SparseMatrix<double>, Vector<double> >
* preconditioning("jacobi", 1.);
*
* preconditioning.use_matrix(A);
*
* solver_selector.solve(A,x,b,preconditioning);
* @endcode
* Now the use of the @p SolverSelector in combination with the @p PreconditionSelector
* allows the user to select both, the solver and the preconditioner, at the
* beginning of his program and each time the
* solver is started (that is several times e.g. in a nonlinear iteration) this
* preselected solver and preconditioner is called.
*
* @author Ralf Hartmann, 1999
*/
template <class MATRIX = SparseMatrix<double>,
class VECTOR = dealii::Vector<double> >
class PreconditionSelector : public Subscriptor
{
public:
/**
* Constructor. @p omega denotes
* the damping parameter of
* the preconditioning.
*/
PreconditionSelector(const std::string &preconditioning,
const typename VECTOR::value_type &omega=1.);
/**
* Destructor.
*/
virtual ~PreconditionSelector();
/**
* Takes the matrix that is needed
* for preconditionings that involves a
* matrix. e.g. for @p precondition_jacobi,
* <tt>~_sor</tt>, <tt>~_ssor</tt>.
*/
void use_matrix(const MATRIX &M);
/**
* Precondition procedure. Calls the
* preconditioning that was specified in
* the constructor.
*/
virtual void vmult (VECTOR &dst, const VECTOR &src) const;
/**
* Get the names of all implemented
* preconditionings.
*/
static std::string get_precondition_names();
/** @addtogroup Exceptions
* @{ */
/**
* Exception.
*/
DeclException0 (ExcNoMatrixGivenToUse);
//@}
protected:
/**
* Stores the name of the
* preconditioning.
*/
std::string preconditioning;
private:
/**
* Matrix that is used for the
* matrix-builtin preconditioning function.
* cf. also @p PreconditionUseMatrix.
*/
SmartPointer<const MATRIX,PreconditionSelector<MATRIX,VECTOR> > A;
/**
* Stores the damping parameter
* of the preconditioner.
*/
const typename VECTOR::value_type omega;
};
/*@}*/
/* --------------------- Inline and template functions ------------------- */
template <class MATRIX, class VECTOR>
PreconditionSelector<MATRIX,VECTOR>
::PreconditionSelector(const std::string &preconditioning,
const typename VECTOR::value_type &omega) :
preconditioning(preconditioning),
omega(omega) {}
template <class MATRIX, class VECTOR>
PreconditionSelector<MATRIX,VECTOR>::~PreconditionSelector()
{
// release the matrix A
A=0;
}
template <class MATRIX, class VECTOR>
void PreconditionSelector<MATRIX,VECTOR>::use_matrix(const MATRIX &M)
{
A=&M;
}
template <class MATRIX, class VECTOR>
void PreconditionSelector<MATRIX,VECTOR>::vmult (VECTOR &dst,
const VECTOR &src) const
{
if (preconditioning=="none")
{
dst=src;
}
else
{
Assert(A!=0, ExcNoMatrixGivenToUse());
if (preconditioning=="jacobi")
{
A->precondition_Jacobi(dst,src,omega);
}
else if (preconditioning=="sor")
{
A->precondition_SOR(dst,src,omega);
}
else if (preconditioning=="ssor")
{
A->precondition_SSOR(dst,src,omega);
}
else
Assert(false,ExcNotImplemented());
}
}
template <class MATRIX, class VECTOR>
std::string PreconditionSelector<MATRIX,VECTOR>::get_precondition_names()
{
return "none|jacobi|sor|ssor";
}
DEAL_II_NAMESPACE_CLOSE
#endif
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