pointdiagonalwrapper.hh

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// -*- tab-width: 2; indent-tabs-mode: nil -*-
// vi: set et ts=2 sw=2 sts=2:
#ifndef DUNE_PDELAB_LOCALOPERATOR_POINTDIAGONALWRAPPER_HH
#define DUNE_PDELAB_LOCALOPERATOR_POINTDIAGONALWRAPPER_HH
 
namespace Dune {
  namespace PDELab {
 
    namespace impl {
      // This wraps a matrix accumulation view and only accumulates if diagonal
      // is set to true and if the indices i and j are equal. Can be used to
      // accumulate the point diagonal.
      template <typename AccumulationView>
      class PointDiagonalAccumulationViewWrapper
      {
      public:
        PointDiagonalAccumulationViewWrapper(AccumulationView& view, bool diagonal)
          : _view(view), _diagonal(diagonal)
        {}
 
        template <typename LFSU, typename I, typename LFSV, typename J, typename Value>
        void accumulate(const LFSU& lfsu, I i, const LFSV& lfsv, J j, Value value)
        {
          if (_diagonal && i == j){
            _view.accumulate(lfsu, i, value);
          }
        }
 
      private:
        AccumulationView& _view;
        bool _diagonal;
      };
 
    } // namespace impl
 
 
    template <class LocalOperator>
    class PointDiagonalLocalOperatorWrapper
      :  public Dune::PDELab::LocalOperatorDefaultFlags
    {
    public:
      // We only want to assemble the point diagonal so we only need volume
      // pattern.
      static constexpr bool doPatternVolume = true;
 
      // For assembling the point diagonal correctly we might need to call
      // volume, skeleton and boundary
      static constexpr bool doAlphaVolume = LocalOperator::doAlphaVolume;
      static constexpr bool doAlphaSkeleton = LocalOperator::doAlphaSkeleton;
      static constexpr bool doAlphaBoundary = LocalOperator::doAlphaBoundary;
 
      // If the underlying lop is linear, this one will be linear too
      static constexpr bool isLinear = LocalOperator::isLinear;
 
      // This wrapper is designed to use two sided assembly. If it was just
      // about assembling the whole diagonal block matrix one sided assembly
      // would be more efficient. For the implementation of matrix-free
      // preconditioner we need to assemble a diagonal block locally for a
      // given cell so we need to assemble in a two sided fashion.
      static constexpr bool doSkeletonTwoSided = true;
 
      PointDiagonalLocalOperatorWrapper(const LocalOperator& localOperator)
        : _localOperator(localOperator)
 
      {}
 
      PointDiagonalLocalOperatorWrapper(const PointDiagonalLocalOperatorWrapper& other)
        : _localOperator(other._localOperator)
      {}
 
      // define sparsity pattern of operator representation
      template<typename LFSU, typename LFSV, typename LocalPattern>
      void pattern_volume (const LFSU& lfsu, const LFSV& lfsv,
                           LocalPattern& pattern) const
      {
        _localOperator.pattern_volume(lfsu, lfsv, pattern);
      }
 
      template<typename EG, typename LFSU, typename X, typename LFSV, typename R>
      void alpha_volume (const EG& eg, const LFSU& lfsu, const X& x, const LFSV& lfsv, R& r) const
      {
        impl::PointDiagonalAccumulationViewWrapper<R> view(r, true);
        _localOperator.jacobian_volume(eg, lfsu, x, lfsv, view);
      }
 
      template<typename IG, typename LFSU, typename X, typename LFSV, typename R>
      void alpha_skeleton (const IG& ig,
                           const LFSU& lfsu_s, const X& x_s, const LFSV& lfsv_s,
                           const LFSU& lfsu_n, const X& x_n, const LFSV& lfsv_n,
                           R& r_s, R& r_n) const
      {
        impl::PointDiagonalAccumulationViewWrapper<R> view_ss(r_s, true);
        impl::PointDiagonalAccumulationViewWrapper<R> view_other(r_s, false);
        _localOperator.jacobian_skeleton(ig,
                                         lfsu_s, x_s, lfsv_s,
                                         lfsu_n, x_n, lfsv_n,
                                         view_ss, view_other, view_other, view_other);
      }
 
      template<typename IG, typename LFSU, typename X, typename LFSV, typename R>
      void alpha_boundary (const IG& ig,
                         const LFSU& lfsu_s, const X& x_s, const LFSV& lfsv_s,
                         R& r_s) const
      {
        impl::PointDiagonalAccumulationViewWrapper<R> view(r_s, true);
        _localOperator.jacobian_boundary(ig, lfsu_s, x_s, lfsv_s, view);
      }
 
    private:
      const LocalOperator& _localOperator;
    };
 
    template <typename LocalOperator, typename EG, typename LFSU, typename X, typename LFSV, typename Y>
    void assembleLocalPointDiagonal(const LocalOperator& localOperator,
                                    const EG& eg,
                                    const LFSU& lfsu,
                                    const X& x,
                                    const LFSV& lfsv,
                                    Y& y)
    {
      // Assemble the volume part
      localOperator.alpha_volume(eg, lfsu, x, lfsv, y);
 
      // Iterate over the intersections
      auto entitySet = lfsu.gridFunctionSpace().entitySet();
      std::size_t intersectionIndex = 0;
      for (const auto& is : intersections(lfsu.gridFunctionSpace().gridView(), eg.entity()))
      {
        Dune::PDELab::IntersectionGeometry<
          typename std::remove_reference<
            typename std::remove_const<
              decltype(is)
              >::type
            >::type
          > ig(is, intersectionIndex++);
        auto intersectionData = classifyIntersection(entitySet, is);
        auto intersectionType = std::get<0>(intersectionData);
 
        // Assemble the intersection part
        switch (intersectionType){
        case Dune::PDELab::IntersectionType::skeleton:
          localOperator.alpha_skeleton(ig, lfsu, x, lfsv, lfsu, x, lfsv, y, y);
          break;
        case Dune::PDELab::IntersectionType::boundary:
          localOperator.alpha_boundary(ig, lfsu, x, lfsv, y);
          break;
        default:
          break;
        }
      }
    }
 
  } // namespace PDELab
} // namespace Dune
 
#endif