KrylovPreconditioner.h

/******************************************************************************
 *
 * AMDiS - Adaptive multidimensional simulations
 *
 * Copyright (C) 2013 Dresden University of Technology. All Rights Reserved.
 * Web: https://fusionforge.zih.tu-dresden.de/projects/amdis
 *
 * Authors:
 * Simon Vey, Thomas Witkowski, Andreas Naumann, Simon Praetorius, et al.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *
 * This file is part of AMDiS
 *
 * See also license.opensource.txt in the distribution.
 *
 ******************************************************************************/


/** \file KrylovPreconditioner.h */

#ifndef AMDIS_KRYLOV_PRECONDITIONER_H
#define AMDIS_KRYLOV_PRECONDITIONER_H

#include "solver/ITL_Preconditioner.h"
#ifdef HAVE_PARALLEL_MTL4
#include "parallel/PITL_Solver.h"
#endif

namespace AMDiS {

  /**
   * \ingroup Solver
   *
   * \brief Implements an inner solver for (flexible) krylov subspace solvers
   *
   * Any AMDiS solver can be used as preconditioner for any other AMDiS solver.
   * Initfile-syntax:<br />
   * [...]->solver: any-krylov-solver<br />
   * [...]->solver->left precon: [krylov|solver]<br />
   * [...]->solver->left precon->solver: any-amdis-solver<br />
   * [...]->solver->left precon->solver->parameter1: ...<br />
   * [...]->solver->left precon->solver->parameter2: ...<br />
   * [...]->solver->left precon->solver->parameter3: ...
   *
   * This Krylov-Preconditioner can also be used as preconditioner for the inner solver, so
   * that a sequence of iner-inner-solver can be loaded.
   **/

  template< typename MatrixType, typename VectorType >
  struct KrylovPreconditioner : ITL_PreconditionerBase< MatrixType, VectorType >
  {
    typedef ITL_PreconditionerBase< MatrixType, VectorType >  precon_base;
    typedef KrylovPreconditioner< MatrixType, VectorType >    self;

    class Creator : public CreatorInterfaceName<precon_base>
    {
    public:
      virtual ~Creator() {}

      precon_base* create() {
	return new self(this->name);
      }
    };

    KrylovPreconditioner(std::string name)
      : fullMatrix(NULL),
	solver(NULL),
	runner(NULL)
    {
#ifdef HAVE_PARALLEL_DOMAIN_AMDIS
      std::string backend = "p_";
#else
      std::string backend = "";
#endif

#if defined(HAVE_PARALLEL_PETSC) || defined(HAVE_SEQ_PETSC)
      backend += "petsc";
#else
      backend += "mtl";
#endif

      // === read backend-name ===
      std::string initFileStr = name + "->solver";
      Parameters::get(initFileStr + "->backend", backend);

      // === read solver-name ===
      std::string solverType("0");
      Parameters::get(initFileStr, solverType);

      if (backend != "0" && backend != "no" && backend != "")
	solverType = backend + "_" + solverType;

      LinearSolverCreator *solverCreator =
	dynamic_cast<LinearSolverCreator*>(CreatorMap<LinearSolverInterface>::getCreator(solverType, initFileStr));
      TEST_EXIT(solverCreator)
	("No valid solver type found in parameter \"%s\"\n", initFileStr.c_str());
      solverCreator->setName(initFileStr);
      solver = solverCreator->create();

      runner = dynamic_cast<RunnerBase< MatrixType, VectorType >*>(solver->getRunner());
    }

    virtual ~KrylovPreconditioner()
    {
      delete solver;
    }

    /// Implementation of \ref ITL_PreconditionerBase::init()
    virtual void init(const SolverMatrix<Matrix<DOFMatrix*> >& A, const MatrixType& fullMatrix_) override
    {
      fullMatrix = &fullMatrix_;
      runner->init(A, fullMatrix_);
    }

    /// Implementation of \ref PreconditionerInterface::init()
    virtual void exit() override
    {
      runner->exit();
    }

    /// Implementation of \ref ITL_PreconditionerBase::solve()
    virtual void solve(const VectorType& b, VectorType& x) const override
    {
      initVector(x);
      runner->solve(*fullMatrix, x, b);
    }

    /// Implementation of \ref ITL_PreconditionerBase::adjoint_solve()
    virtual void adjoint_solve(const VectorType& b, VectorType& x) const override
    {
      initVector(x);
      runner->adjoint_solve(*fullMatrix, x, b);
    }

  protected: // methods

    template<typename VectorT>
    typename boost::enable_if< mtl::traits::is_distributed<VectorT>, void >::type
    initVector(VectorT& x) const
    {
#ifdef HAVE_PARALLEL_MTL4
      x.init_distribution(col_distribution(*fullMatrix), num_cols(*fullMatrix));
#endif
      set_to_zero(x);
    }

    template<typename VectorT>
    typename boost::disable_if< mtl::traits::is_distributed<VectorT>, void >::type
    initVector(VectorT& x) const
    {
      x.change_dim(num_cols(*fullMatrix));
      set_to_zero(x);
    }

  protected: // member variables

    const MatrixType* fullMatrix;

    LinearSolverInterface* solver;
    RunnerBase< MatrixType, VectorType >* runner;
  };


#ifdef HAVE_PARALLEL_MTL4
  typedef KrylovPreconditioner<MTLTypes::PMTLMatrix, MTLTypes::PMTLVector> KrylovPreconditionerParallel;
#endif
  typedef KrylovPreconditioner<MTLTypes::MTLMatrix, MTLTypes::MTLVector> KrylovPreconditionerSeq;


} // end namespace AMDiS

#endif // AMDIS_KRYLOV_PRECONDITIONER_H