mesh_function.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2026 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 
 
#ifndef LIBMESH_MESH_FUNCTION_H
#define LIBMESH_MESH_FUNCTION_H
 
// Local Includes
#include "libmesh/function_base.h"
#include "libmesh/dense_vector.h"
#include "libmesh/vector_value.h"
#include "libmesh/tensor_value.h"
#include "libmesh/tree_base.h"
#include "libmesh/parallel_object.h"
 
// C++ includes
#include <cstddef>
#include <vector>
#include <memory>
 
namespace libMesh
{
 
 
// Forward Declarations
template <typename T> class DenseVector;
class EquationSystems;
template <typename T> class NumericVector;
class DofMap;
class PointLocatorBase;
 
class MeshFunction : public FunctionBase<Number>,
                     public ParallelObject
{
public:
 
  MeshFunction (const EquationSystems & eqn_systems,
                const NumericVector<Number> & vec,
                const DofMap & dof_map,
                std::vector<unsigned int> vars,
                const FunctionBase<Number> * master=nullptr);
 
  MeshFunction (const EquationSystems & eqn_systems,
                const NumericVector<Number> & vec,
                const DofMap & dof_map,
                const unsigned int var,
                const FunctionBase<Number> * master=nullptr);
 
  MeshFunction (const MeshFunction & mf);
 
  MeshFunction (MeshFunction &&) = default;
  MeshFunction & operator= (const MeshFunction &) = delete;
  MeshFunction & operator= (MeshFunction &&) = delete;
 
  ~MeshFunction ();
 
  virtual void init () override;
 
  virtual void clear () override;
 
  virtual std::unique_ptr<FunctionBase<Number>> clone () const override;
 
  virtual Number operator() (const Point & p,
                             const Real time=0.) override;
 
  std::map<const Elem *, Number> discontinuous_value (const Point & p,
                                                      const Real time=0.);
 
  Gradient gradient (const Point & p,
                     const Real time=0.);
 
  std::map<const Elem *, Gradient> discontinuous_gradient (const Point & p,
                                                           const Real time=0.);
 
#ifdef LIBMESH_ENABLE_SECOND_DERIVATIVES
  Tensor hessian (const Point & p,
                  const Real time=0.);
#endif
 
  virtual void operator() (const Point & p,
                           const Real time,
                           DenseVector<Number> & output) override;
 
  void operator() (const Point & p,
                   const Real time,
                   DenseVector<Number> & output,
                   const std::set<subdomain_id_type> * subdomain_ids);
 
  void discontinuous_value (const Point & p,
                            const Real time,
                            std::map<const Elem *, DenseVector<Number>> & output);
 
  void discontinuous_value (const Point & p,
                            const Real time,
                            std::map<const Elem *, DenseVector<Number>> & output,
                            const std::set<subdomain_id_type> * subdomain_ids);
 
  void gradient (const Point & p,
                 const Real time,
                 std::vector<Gradient> & output);
 
  void gradient (const Point & p,
                 const Real time,
                 std::vector<Gradient> & output,
                 const std::set<subdomain_id_type> * subdomain_ids);
 
  void discontinuous_gradient (const Point & p,
                               const Real time,
                               std::map<const Elem *, std::vector<Gradient>> & output);
 
  void discontinuous_gradient (const Point & p,
                               const Real time,
                               std::map<const Elem *, std::vector<Gradient>> & output,
                               const std::set<subdomain_id_type> * subdomain_ids);
 
  void hessian (const Point & p,
                const Real time,
                std::vector<Tensor> & output);
 
  void hessian (const Point & p,
                const Real time,
                std::vector<Tensor> & output,
                const std::set<subdomain_id_type> * subdomain_ids);
 
  const PointLocatorBase & get_point_locator () const;
  PointLocatorBase & get_point_locator ();
 
  void enable_out_of_mesh_mode(const DenseVector<Number> & value);
 
  void enable_out_of_mesh_mode(const Number & value);
 
  void disable_out_of_mesh_mode();
 
  void set_point_locator_tolerance(Real tol);
 
  void unset_point_locator_tolerance();
 
  void set_subdomain_ids(const std::set<subdomain_id_type> * subdomain_ids);
 
protected:
 
  const Elem * find_element(const Point & p,
                            const std::set<subdomain_id_type> * subdomain_ids = nullptr) const;
 
  std::set<const Elem *> find_elements(const Point & p,
                                       const std::set<subdomain_id_type> * subdomain_ids = nullptr) const;
 
  const Elem * check_found_elem(const Elem * element, const Point & p) const;
 
  void _gradient_on_elem (const Point & p,
                          const Elem * element,
                          std::vector<Gradient> & output);
 
  const EquationSystems & _eqn_systems;
 
  const NumericVector<Number> & _vector;
 
  const DofMap & _dof_map;
 
  const std::vector<unsigned int> _system_vars;
 
  std::unique_ptr<PointLocatorBase> _point_locator;
 
  std::unique_ptr<std::set<subdomain_id_type>> _subdomain_ids;
 
  bool _out_of_mesh_mode;
 
  DenseVector<Number> _out_of_mesh_value;
};
 
 
} // namespace libMesh
 
 
#endif // LIBMESH_MESH_FUNCTION_H