/**
 * @file   discretization_poisson_fv.hpp
 * @author Julian Iseringhausen <isering@ins.uni-bonn.de>
 * @date   Mon Apr 18 13:03:47 2011
 *
 * @brief  Finite volume discretization for the Poisson
 *         equation. Absolutely equivalent to the finite
 *         difference discretization unless you use
 *         hierarchically coarsened grids.
 *
 */

#ifndef DISCRETIZATION_POISSON_FV_HPP_
#define DISCRETIZATION_POISSON_FV_HPP_

#include "base/discretization.hpp"

namespace VMG
{

static inline vmg_float sqr(const vmg_float& val) {return val*val;}

class DiscretizationPoissonFV : public Discretization
{
public:
  DiscretizationPoissonFV()
  {
    stencil.SetDiag(6.0);
    stencil.push_back(-1,  0,  0, -1.0);
    stencil.push_back( 1,  0,  0, -1.0);
    stencil.push_back( 0, -1,  0, -1.0);
    stencil.push_back( 0,  1,  0, -1.0);
    stencil.push_back( 0,  0, -1, -1.0);
    stencil.push_back( 0,  0,  1, -1.0);
  }

  vmg_float OperatorPrefactor(const Grid& grid) const
  {
    return 1.0  / sqr(grid.MeshWidth());
  }

private:
  void SetInnerBoundaryCompute(Grid& sol_f, Grid& rhs_f, Grid& sol_c) const;
};

}

#endif /* DISCRETIZATION_POISSON_FV_HPP_ */