/usr/include/deal.II/lac/solver_relaxation.h is in libdeal.ii-dev 8.5.1-3.
This file is owned by root:root, with mode 0o644.
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//
// Copyright (C) 2010 - 2015 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 dealii__solver_relaxation_h
#define dealii__solver_relaxation_h
#include <deal.II/base/config.h>
#include <deal.II/base/logstream.h>
#include <deal.II/lac/solver.h>
#include <deal.II/lac/solver_control.h>
#include <deal.II/base/subscriptor.h>
DEAL_II_NAMESPACE_OPEN
/**
* Implementation of an iterative solver based on relaxation methods. The
* stopping criterion is the norm of the residual.
*
* For the requirements on matrices and vectors in order to work with this
* class, see the documentation of the Solver base class.
*
* Like all other solver classes, this class has a local structure called @p
* AdditionalData which is used to pass additional parameters to the solver,
* like damping parameters or the number of temporary vectors. We use this
* additional structure instead of passing these values directly to the
* constructor because this makes the use of the @p SolverSelector and other
* classes much easier and guarantees that these will continue to work even if
* number or type of the additional parameters for a certain solver changes.
* AdditionalData of this class currently does not contain any data.
*
*
* <h3>Observing the progress of linear solver iterations</h3>
*
* The solve() function of this class uses the mechanism described in the
* Solver base class to determine convergence. This mechanism can also be used
* to observe the progress of the iteration.
*
*
* @ingroup Solvers
* @author Guido Kanschat
* @date 2010
*/
template <typename VectorType = Vector<double> >
class SolverRelaxation : public Solver<VectorType>
{
public:
/**
* Standardized data struct to pipe additional data to the solver. There is
* no data in here for relaxation methods.
*/
struct AdditionalData {};
/**
* Constructor.
*/
SolverRelaxation (SolverControl &cn,
const AdditionalData &data=AdditionalData());
/**
* Virtual destructor.
*/
virtual ~SolverRelaxation ();
/**
* Solve the system $Ax = b$ using the relaxation method $x_{k+1} =
* R(x_k,b)$. The matrix <i>A</i> itself is only used to compute the
* residual.
*/
template<typename MatrixType, class RelaxationType>
void
solve (const MatrixType &A,
VectorType &x,
const VectorType &b,
const RelaxationType &R);
};
//----------------------------------------------------------------------//
template <class VectorType>
SolverRelaxation<VectorType>::SolverRelaxation (SolverControl &cn,
const AdditionalData &)
:
Solver<VectorType> (cn)
{}
template <class VectorType>
SolverRelaxation<VectorType>::~SolverRelaxation()
{}
template <class VectorType>
template <typename MatrixType, class RelaxationType>
void
SolverRelaxation<VectorType>::solve (const MatrixType &A,
VectorType &x,
const VectorType &b,
const RelaxationType &R)
{
GrowingVectorMemory<VectorType> mem;
SolverControl::State conv=SolverControl::iterate;
// Memory allocation
typename VectorMemory<VectorType>::Pointer Vr(mem);
VectorType &r = *Vr;
r.reinit(x);
typename VectorMemory<VectorType>::Pointer Vd(mem);
VectorType &d = *Vd;
d.reinit(x);
deallog.push("Relaxation");
int iter=0;
try
{
// Main loop
for (; conv==SolverControl::iterate; iter++)
{
// Compute residual
A.vmult(r,x);
r.sadd(-1.,1.,b);
// The required norm of the
// (preconditioned)
// residual is computed in
// criterion() and stored
// in res.
conv = this->iteration_status (iter, r.l2_norm(), x);
if (conv != SolverControl::iterate)
break;
R.step(x,b);
}
}
catch (...)
{
deallog.pop();
throw;
}
deallog.pop();
// in case of failure: throw exception
AssertThrow(conv == SolverControl::success,
SolverControl::NoConvergence (iter, r.l2_norm()));
// otherwise exit as normal
}
DEAL_II_NAMESPACE_CLOSE
#endif
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