FirstOrderTestvecGradTrial.hpp

#pragma once
 
#include <type_traits>
 
#include <amdis/GridFunctionOperator.hpp>
#include <amdis/common/StaticSize.hpp>
 
#include <dune/common/typetree/nodeconcepts.hh>
 
namespace AMDiS
{
  namespace tag
  {
    struct testvec_gradtrial {};
  }
 
 
  class FirstOrderTestvecGradTrial
  {
  public:
    FirstOrderTestvecGradTrial(tag::testvec_gradtrial) {}
 
    template <class CG, class RN, class CN, class Quad, class LocalFct, class Mat>
    void assemble(CG const& contextGeo, RN const& rowNode, CN const& colNode,
                  Quad const& quad, LocalFct const& localFct, Mat& elementMatrix) const
    {
      static_assert(static_size_v<typename LocalFct::Range> == 1,
        "Expression must be of scalar type.");
      static_assert(Dune::TypeTree::Concept::UniformInnerTreeNode<RN> && Dune::TypeTree::Concept::LeafTreeNode<CN>,
        "col-node must be Leaf-Node and row-node must be a Power-Node.");
 
      assert( rowNode.degree() == CG::dow );
 
      std::size_t rowSize = rowNode.child(0).size();
      std::size_t colSize = colNode.size();
 
      using RangeFieldType = typename CN::LocalBasis::Traits::RangeFieldType;
      using WorldVector = FieldVector<RangeFieldType,CG::dow>;
      std::vector<WorldVector> colGradients;
 
      for (auto const& qp : quad) {
        // Position of the current quadrature point in the reference element
        decltype(auto) local = contextGeo.coordinateInElement(qp.position());
 
        // The transposed inverse Jacobian of the map from the reference element to the element
        const auto jacobian = contextGeo.elementGeometry().jacobianInverseTransposed(local);
 
        // The multiplicative factor in the integral transformation formula
        const auto factor = localFct(local) * contextGeo.integrationElement(qp.position()) * qp.weight();
 
        // the values of the shape functions on the reference element at the quadrature point
        auto const& shapeValues = rowNode.child(0).localBasisValuesAt(local);
 
        // The gradients of the shape functions on the reference element
        auto const& shapeGradients = colNode.localBasisJacobiansAt(local);
 
        // Compute the shape function gradients on the real element
        colGradients.resize(shapeGradients.size());
 
        for (std::size_t i = 0; i < colGradients.size(); ++i)
          jacobian.mv(shapeGradients[i][0], colGradients[i]);
 
        for (std::size_t i = 0; i < rowSize; ++i) {
          const auto value = factor * shapeValues[i];
          for (std::size_t j = 0; j < colSize; ++j) {
            const auto local_j = colNode.localIndex(j);
            for (std::size_t k = 0; k < rowNode.degree(); ++k) {
              const auto local_ki = rowNode.child(k).localIndex(i);
              elementMatrix[local_ki][local_j] += value * colGradients[j][k];
            }
          }
        }
      }
 
    }
  };
 
  template <class LC>
  struct GridFunctionOperatorRegistry<tag::testvec_gradtrial, LC>
  {
    static constexpr int degree = 1;
    using type = FirstOrderTestvecGradTrial;
  };
 
} // end namespace AMDiS