LocalSolver.h

// Copyright (C) 2013-2015 Garth N. Wells
//
// This file is part of DOLFIN.
//
// DOLFIN is free software: you can 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 3 of the License, or
// (at your option) any later version.
//
// DOLFIN is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with DOLFIN. If not, see <http://www.gnu.org/licenses/>.

#ifndef __LOCAL_SOLVER_H
#define __LOCAL_SOLVER_H

#include <memory>
#include <vector>
#include <Eigen/Cholesky>
#include <Eigen/Dense>
#include <Eigen/LU>

namespace dolfin
{
  // Forward declarations
  class Form;
  class Function;
  class GenericDofMap;
  class GenericVector;


  class LocalSolver
  {
  public:

    enum class SolverType {LU, Cholesky};

    LocalSolver(std::shared_ptr<const Form> a, std::shared_ptr<const Form> L,
                SolverType solver_type=SolverType::LU);

    LocalSolver(std::shared_ptr<const Form> a, SolverType solver_type=SolverType::LU);

    void solve_global_rhs(Function& u) const;

    void solve_local_rhs(Function& u) const;

    void solve_local(GenericVector& x, const GenericVector& b,
                     const GenericDofMap& dofmap_b) const;

    void factorize();

    void clear_factorization();

  private:

    // Bilinear and linear forms
    std::shared_ptr<const Form> _a, _formL;

    // Solver type to use
    const SolverType _solver_type;

    // Cached LU factorisations of matrices (_spd==false)
    std::vector<Eigen::PartialPivLU<Eigen::Matrix<double, Eigen::Dynamic,
                                                  Eigen::Dynamic,
                                                  Eigen::RowMajor>>> _lu_cache;

    // Cached Cholesky factorisations of matrices (_spd==true)
    std::vector<Eigen::LLT<Eigen::Matrix<double, Eigen::Dynamic,
                                         Eigen::Dynamic,
                                         Eigen::RowMajor>>> _cholesky_cache;

    // Helper function that does the actual calculations
    void _solve_local(GenericVector& x,
                      const GenericVector* global_b,
                      const GenericDofMap* dofmap_L) const;
  };

}

#endif