mapping_data_on_the_fly.h

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// -----------------------------------------------------------------------------
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception OR LGPL-2.1-or-later
// Copyright (C) 2014 - 2024 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Detailed license information governing the source code and contributions
// can be found in LICENSE.md and CONTRIBUTING.md at the top level directory.
//
// -----------------------------------------------------------------------------
 
 
#ifndef dealii_matrix_free_mapping_data_on_the_fly_h
#define dealii_matrix_free_mapping_data_on_the_fly_h
 
 
#include <deal.II/base/config.h>
 
#include <deal.II/base/aligned_vector.h>
#include <deal.II/base/enable_observer_pointer.h>
#include <deal.II/base/exceptions.h>
#include <deal.II/base/vectorization.h>
 
#include <deal.II/fe/fe_nothing.h>
#include <deal.II/fe/fe_values.h>
#include <deal.II/fe/mapping_q1.h>
 
#include <deal.II/matrix_free/mapping_info.h>
#include <deal.II/matrix_free/shape_info.h>
 
 
DEAL_II_NAMESPACE_OPEN
 
 
namespace internal
{
  namespace MatrixFreeFunctions
  {
    template <int dim, typename Number>
    class MappingDataOnTheFly
    {
    public:
      MappingDataOnTheFly() = default;

      MappingDataOnTheFly(const Mapping<dim>  &mapping,
                          const Quadrature<1> &quadrature,
                          const UpdateFlags    update_flags);

      MappingDataOnTheFly(const Quadrature<1> &quadrature,
                          const UpdateFlags    update_flags);

      void
      reinit(typename ::Triangulation<dim>::cell_iterator cell);

      bool
      is_initialized() const;

      typename ::Triangulation<dim>::cell_iterator
      get_cell() const;

      const ::FEValues<dim> &
      get_fe_values() const;

      const MappingInfoStorage<dim, dim, Number> &
      get_data_storage() const;

      MappingInfoStorage<dim, dim, Number> &
      get_data_storage();

      const Quadrature<1> &
      get_quadrature() const;
 
    private:
      typename ::Triangulation<dim>::cell_iterator present_cell;

      std::unique_ptr<FE_Nothing<dim>> fe_dummy;

      std::unique_ptr<::FEValues<dim>> fe_values;

      const Quadrature<1> quadrature_1d;

      MappingInfoStorage<dim, dim, Number> mapping_info_storage;
    };
 
 
    /*-------------------------- Inline functions ---------------------------*/
 
    template <int dim, typename Number>
    inline MappingDataOnTheFly<dim, Number>::MappingDataOnTheFly(
      const Mapping<dim>  &mapping,
      const Quadrature<1> &quadrature,
      const UpdateFlags    update_flags)
      : fe_dummy(std::make_unique<FE_Nothing<dim>>())
      , fe_values(std::make_unique<::FEValues<dim>>(
          mapping,
          *fe_dummy,
          Quadrature<dim>(quadrature),
          MappingInfoStorage<dim, dim, Number>::compute_update_flags(
            update_flags)))
      , quadrature_1d(quadrature)
    {
      mapping_info_storage.descriptor.resize(1);
      mapping_info_storage.descriptor[0].initialize(quadrature);
      mapping_info_storage.data_index_offsets.resize(1);
      mapping_info_storage.JxW_values.resize(fe_values->n_quadrature_points);
      mapping_info_storage.jacobians[0].resize(fe_values->n_quadrature_points);
      if (update_flags & update_quadrature_points)
        {
          mapping_info_storage.quadrature_point_offsets.resize(1, 0);
          mapping_info_storage.quadrature_points.resize(
            fe_values->n_quadrature_points);
        }
      if (fe_values->get_update_flags() & update_normal_vectors)
        {
          mapping_info_storage.normal_vectors.resize(
            fe_values->n_quadrature_points);
          mapping_info_storage.normals_times_jacobians[0].resize(
            fe_values->n_quadrature_points);
        }
      Assert(!(fe_values->get_update_flags() & update_jacobian_grads),
             ExcNotImplemented());
    }
 
 
 
    template <int dim, typename Number>
    inline MappingDataOnTheFly<dim, Number>::MappingDataOnTheFly(
      const Quadrature<1> &quadrature,
      const UpdateFlags    update_flags)
      : MappingDataOnTheFly(::StaticMappingQ1<dim, dim>::mapping,
                            quadrature,
                            update_flags)
    {}
 
 
 
    template <int dim, typename Number>
    inline void
    MappingDataOnTheFly<dim, Number>::reinit(
      typename ::Triangulation<dim>::cell_iterator cell)
    {
      if (present_cell == cell)
        return;
      present_cell = cell;
      fe_values->reinit(present_cell);
      for (unsigned int q = 0; q < fe_values->get_quadrature().size(); ++q)
        {
          if (fe_values->get_update_flags() & update_JxW_values)
            mapping_info_storage.JxW_values[q] = fe_values->JxW(q);
          if (fe_values->get_update_flags() & update_jacobians)
            {
              Tensor<2, dim> jac = fe_values->jacobian(q);
              jac                = invert(transpose(jac));
              for (unsigned int d = 0; d < dim; ++d)
                for (unsigned int e = 0; e < dim; ++e)
                  mapping_info_storage.jacobians[0][q][d][e] = jac[d][e];
            }
          if (fe_values->get_update_flags() & update_quadrature_points)
            for (unsigned int d = 0; d < dim; ++d)
              mapping_info_storage.quadrature_points[q][d] =
                fe_values->quadrature_point(q)[d];
          if (fe_values->get_update_flags() & update_normal_vectors)
            {
              for (unsigned int d = 0; d < dim; ++d)
                mapping_info_storage.normal_vectors[q][d] =
                  fe_values->normal_vector(q)[d];
              mapping_info_storage.normals_times_jacobians[0][q] =
                mapping_info_storage.normal_vectors[q] *
                mapping_info_storage.jacobians[0][q];
            }
        }
    }
 
 
 
    template <int dim, typename Number>
    inline bool
    MappingDataOnTheFly<dim, Number>::is_initialized() const
    {
      return present_cell !=
             typename ::Triangulation<dim>::cell_iterator();
    }
 
 
 
    template <int dim, typename Number>
    inline typename ::Triangulation<dim>::cell_iterator
    MappingDataOnTheFly<dim, Number>::get_cell() const
    {
      return fe_values->get_cell();
    }
 
 
 
    template <int dim, typename Number>
    inline const ::FEValues<dim> &
    MappingDataOnTheFly<dim, Number>::get_fe_values() const
    {
      return *fe_values;
    }
 
 
 
    template <int dim, typename Number>
    inline const MappingInfoStorage<dim, dim, Number> &
    MappingDataOnTheFly<dim, Number>::get_data_storage() const
    {
      return mapping_info_storage;
    }
 
 
 
    template <int dim, typename Number>
    inline MappingInfoStorage<dim, dim, Number> &
    MappingDataOnTheFly<dim, Number>::get_data_storage()
    {
      return mapping_info_storage;
    }
 
 
 
    template <int dim, typename Number>
    inline const Quadrature<1> &
    MappingDataOnTheFly<dim, Number>::get_quadrature() const
    {
      return quadrature_1d;
    }
 
 
  } // end of namespace MatrixFreeFunctions
} // end of namespace internal
 
 
DEAL_II_NAMESPACE_CLOSE
 
#endif