fe_nothing.h

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// -----------------------------------------------------------------------------
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception OR LGPL-2.1-or-later
// Copyright (C) 2009 - 2026 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_fe_nothing_h
#define dealii_fe_nothing_h
 
#include <deal.II/base/config.h>
 
#include <deal.II/base/table.h>
#include <deal.II/base/utilities.h>
 
#include <deal.II/fe/fe.h>
#include <deal.II/fe/fe_data.h>
#include <deal.II/fe/fe_update_flags.h>
#include <deal.II/fe/mapping.h>
#include <deal.II/fe/mapping_related_data.h>
 
#include <deal.II/grid/reference_cell.h>
#include <deal.II/grid/tria.h>
 
#include <deal.II/hp/q_collection.h>
 
#include <deal.II/lac/full_matrix.h>
 
#include <iterator>
#include <memory>
#include <string>
#include <utility>
#include <vector>
 
DEAL_II_NAMESPACE_OPEN
 
 
template <int dim, int spacedim = dim>
class FE_Nothing : public FiniteElement<dim, spacedim>
{
public:
  FE_Nothing(const ReferenceCell<dim> &type,
             const unsigned int        n_components = 1,
             const bool                dominate     = false);
 
  FE_Nothing(const unsigned int n_components = 1, const bool dominate = false);
 
  virtual std::unique_ptr<FiniteElement<dim, spacedim>>
  clone() const override;
 
  virtual std::string
  get_name() const override;
 
  // for documentation, see the FiniteElement base class
  virtual UpdateFlags
  requires_update_flags(const UpdateFlags update_flags) const override;
 
  virtual double
  shape_value(const unsigned int i, const Point<dim> &p) const override;
 
  virtual void
  fill_fe_values(
    const typename Triangulation<dim, spacedim>::cell_iterator &cell,
    const CellSimilarity::Similarity                            cell_similarity,
    const Quadrature<dim>                                      &quadrature,
    const Mapping<dim, spacedim>                               &mapping,
    const typename Mapping<dim, spacedim>::InternalDataBase &mapping_internal,
    const internal::FEValuesImplementation::MappingRelatedData<dim, spacedim>
                                                                  &mapping_data,
    const typename FiniteElement<dim, spacedim>::InternalDataBase &fe_internal,
    ::internal::FEValuesImplementation::FiniteElementRelatedData<dim,
                                                                       spacedim>
      &output_data) const override;
 
  using FiniteElement<dim, spacedim>::fill_fe_face_values;
 
  virtual void
  fill_fe_face_values(
    const typename Triangulation<dim, spacedim>::cell_iterator &cell,
    const unsigned int                                          face_no,
    const hp::QCollection<dim - 1>                             &quadrature,
    const Mapping<dim, spacedim>                               &mapping,
    const typename Mapping<dim, spacedim>::InternalDataBase &mapping_internal,
    const internal::FEValuesImplementation::MappingRelatedData<dim, spacedim>
                                                                  &mapping_data,
    const typename FiniteElement<dim, spacedim>::InternalDataBase &fe_internal,
    ::internal::FEValuesImplementation::FiniteElementRelatedData<dim,
                                                                       spacedim>
      &output_data) const override;
 
  virtual void
  fill_fe_subface_values(
    const typename Triangulation<dim, spacedim>::cell_iterator &cell,
    const unsigned int                                          face_no,
    const unsigned int                                          sub_no,
    const Quadrature<dim - 1>                                  &quadrature,
    const Mapping<dim, spacedim>                               &mapping,
    const typename Mapping<dim, spacedim>::InternalDataBase &mapping_internal,
    const internal::FEValuesImplementation::MappingRelatedData<dim, spacedim>
                                                                  &mapping_data,
    const typename FiniteElement<dim, spacedim>::InternalDataBase &fe_internal,
    ::internal::FEValuesImplementation::FiniteElementRelatedData<dim,
                                                                       spacedim>
      &output_data) const override;
 
  virtual std::unique_ptr<
    typename FiniteElement<dim, spacedim>::InternalDataBase>
  get_data(
    const UpdateFlags             update_flags,
    const Mapping<dim, spacedim> &mapping,
    const Quadrature<dim>        &quadrature,
    ::internal::FEValuesImplementation::FiniteElementRelatedData<dim,
                                                                       spacedim>
      &output_data) const override;
 
  virtual FiniteElementDomination::Domination
  compare_for_domination(const FiniteElement<dim, spacedim> &fe_other,
                         const unsigned int codim = 0) const override final;
 
 
 
  virtual std::vector<std::pair<unsigned int, unsigned int>>
  hp_vertex_dof_identities(
    const FiniteElement<dim, spacedim> &fe_other) const override;
 
  virtual std::vector<std::pair<unsigned int, unsigned int>>
  hp_line_dof_identities(
    const FiniteElement<dim, spacedim> &fe_other) const override;
 
  virtual std::vector<std::pair<unsigned int, unsigned int>>
  hp_quad_dof_identities(const FiniteElement<dim, spacedim> &fe_other,
                         const unsigned int face_no = 0) const override;
 
  virtual bool
  hp_constraints_are_implemented() const override;
 
  virtual void
  get_interpolation_matrix(
    const FiniteElement<dim, spacedim> &source_fe,
    FullMatrix<double>                 &interpolation_matrix) const override;
 
  virtual void
  get_face_interpolation_matrix(const FiniteElement<dim, spacedim> &source_fe,
                                FullMatrix<double> &interpolation_matrix,
                                const unsigned int  face_no = 0) const override;
 
 
  virtual void
  get_subface_interpolation_matrix(
    const FiniteElement<dim, spacedim> &source_fe,
    const unsigned int                  index,
    FullMatrix<double>                 &interpolation_matrix,
    const unsigned int                  face_no = 0) const override;
 
  virtual std::pair<Table<2, bool>, std::vector<unsigned int>>
  get_constant_modes() const override;
 
  bool
  is_dominating() const;
 
private:
  const bool dominate;
};
 
 
DEAL_II_NAMESPACE_CLOSE
 
#endif