FirstOrderTestPartialTrial.hpp

#pragma once

#include <type_traits>

#include <amdis/GridFunctionOperator.hpp>
#include <amdis/Output.hpp>
#include <amdis/common/StaticSize.hpp>
#include <amdis/utility/LocalToGlobalAdapter.hpp>

namespace AMDiS
{
  namespace tag
  {
    struct test_partialtrial
    {
      std::size_t comp;
    };

    struct partial_trial
    {
      std::size_t comp;
    };
  }


  template <class LC, class GridFct>
  class GridFunctionOperator<tag::test_partialtrial, LC, GridFct>
      : public GridFunctionOperatorBase<GridFunctionOperator<tag::test_partialtrial, LC, GridFct>, LC, GridFct>
  {
    using Self = GridFunctionOperator;
    using Super = GridFunctionOperatorBase<Self, LC, GridFct>;

    static_assert( static_size_v<typename GridFct::Range> == 1, "Expression must be of scalar type." );

  public:
    GridFunctionOperator(tag::test_partialtrial tag, GridFct const& expr)
      : Super(expr, 1)
      , comp_(tag.comp)
    {}

    template <class CG, class RN, class CN, class Mat>
    void getElementMatrix(CG const& contextGeo, RN const& rowNode, CN const& colNode, Mat& elementMatrix)
    {
      static_assert(RN::isLeaf && CN::isLeaf,
        "Operator can be applied to Leaf-Nodes only.");

      auto const& quad = this->getQuadratureRule(contextGeo.type(), rowNode, colNode);

      std::size_t rowSize = rowNode.size();
      std::size_t colSize = colNode.size();

      LocalToGlobalBasisAdapter colLocalBasis(colNode, contextGeo.geometry());
      for (auto const& qp : quad) {
        // Position of the current quadrature point in the reference element
        decltype(auto) local = contextGeo.local(qp.position());

        // The multiplicative factor in the integral transformation formula
        auto factor = contextGeo.integrationElement(qp.position()) * qp.weight();
        factor *= Super::coefficient(local);

        // the values of the shape functions on the reference element at the quadrature point
        auto const& shapeValues = rowNode.localBasisValuesAt(local);

        // Compute the shape function gradients on the real element
        auto const& colPartial = colLocalBasis.partialsAt(local, comp_);

        for (std::size_t j = 0; j < colSize; ++j) {
          const auto local_j = colNode.localIndex(j);
          const auto value = factor * colPartial[j];
          for (std::size_t i = 0; i < rowSize; ++i) {
            const auto local_i = rowNode.localIndex(i);
            elementMatrix[local_i][local_j] += value * shapeValues[i];
          }
        }
      }
    }

  private:
    std::size_t comp_;
  };


  template <class Expr, class... QuadratureArgs>
  auto fot(Expr&& expr, tag::partial_trial t, QuadratureArgs&&... args)
  {
    return makeOperator(tag::test_partialtrial{t.comp}, FWD(expr), FWD(args)...);
  }

} // end namespace AMDiS