static_condensation_dof_map.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_STATIC_CONDENSATION_DOF_MAP_H
#define LIBMESH_STATIC_CONDENSATION_DOF_MAP_H
 
#include "libmesh/libmesh_config.h"
 
#include "libmesh/id_types.h"
#include "libmesh/libmesh_common.h"
#include "libmesh/dof_map_base.h"
#include "libmesh/variable.h"
#include "libmesh/sparsity_pattern.h"
#include "libmesh/utility.h"
 
#include <unordered_map>
#include <memory>
#include <vector>
 
namespace libMesh
{
class MeshBase;
class System;
class DofMap;
class Elem;
 
class StaticCondensationDofMap : public DofMapBase
{
public:
  StaticCondensationDofMap(MeshBase & mesh, System & system, const DofMap & dof_map);
  virtual ~StaticCondensationDofMap();
 
  //
  // Unique methods
  //
 
  void reinit();
 
  void dont_condense_vars(const std::unordered_set<unsigned int> & vars);
 
  const std::unordered_set<unsigned int> & uncondensed_vars() const { return _uncondensed_vars; }
 
  virtual unsigned int n_variables() const override;
 
  virtual const Variable & variable(const unsigned int c) const override;
 
  virtual void dof_indices(const Elem * const elem,
                           std::vector<dof_id_type> & di,
                           const unsigned int vn,
                           int p_level = -12345) const override;
 
  virtual void dof_indices(const Node * const node,
                           std::vector<dof_id_type> & di,
                           const unsigned int vn) const override;
 
  /*
   * @returns The dummyish reduced system
   */
  const System & reduced_system() const;
 
  /*
   * @returns The mesh
   */
  const MeshBase & mesh () const { return _mesh; }
 
  bool initialized() const { return _sc_is_initialized; }
 
  virtual void clear() override;
 
  dof_id_type get_reduced_from_global_constraint_dof(dof_id_type full_dof) const;
 
private:
  void add_uncondensed_dof_plus_constraint_dofs(
      dof_id_type full_dof_number,
      bool involved_in_constraints,
      std::unordered_map<dof_id_type, dof_id_type> & uncondensed_global_to_local_map,
      std::unordered_set<dof_id_type> & local_uncondensed_dofs_set,
      std::unordered_map<processor_id_type, std::unordered_set<dof_id_type>> &
          nonlocal_uncondensed_dofs,
      std::vector<dof_id_type> & elem_uncondensed_dofs,
      dof_id_type & uncondensed_local_dof_number,
      std::unordered_set<dof_id_type> & constraint_dofs);
 
  void add_uncondensed_dof(
      dof_id_type full_dof_number,
      bool involved_in_constraints,
      std::unordered_map<dof_id_type, dof_id_type> & uncondensed_global_to_local_map,
      std::unordered_set<dof_id_type> & local_uncondensed_dofs_set,
      std::unordered_map<processor_id_type, std::unordered_set<dof_id_type>> &
          nonlocal_uncondensed_dofs,
      std::vector<dof_id_type> & elem_uncondensed_dofs,
      dof_id_type & uncondensed_local_dof_number,
      std::unordered_set<dof_id_type> & constraint_dofs);
 
  struct DofData
  {
    std::vector<std::vector<dof_id_type>> reduced_space_indices;
 
    std::unordered_map<dof_id_type, dof_id_type> uncondensed_global_to_local_map;
    std::unordered_map<dof_id_type, dof_id_type> condensed_global_to_local_map;
  };
 
  friend class StaticCondensation;
 
  std::unordered_map<dof_id_type, DofData> _elem_to_dof_data;
 
  std::vector<dof_id_type> _local_uncondensed_dofs;
 
  MeshBase & _mesh;
  System & _system;
  const DofMap & _dof_map;
 
  std::unordered_set<unsigned int> _uncondensed_vars;
 
  bool _sc_is_initialized;
 
  std::vector<Variable> _reduced_vars;
 
  System * _reduced_system;
 
  std::unique_ptr<SparsityPattern::Build> _reduced_sp;
 
  std::vector<dof_id_type> _reduced_nnz;
 
  std::vector<dof_id_type> _reduced_noz;
 
  std::unordered_map<dof_id_type, dof_id_type> _full_to_reduced_constraint_dofs;
};
 
inline void
StaticCondensationDofMap::dont_condense_vars(const std::unordered_set<unsigned int> & vars)
{
  _uncondensed_vars.insert(vars.begin(), vars.end());
}
 
inline const System & StaticCondensationDofMap::reduced_system() const
{
  libmesh_assert(_reduced_system);
  return *_reduced_system;
}
 
inline dof_id_type
StaticCondensationDofMap::get_reduced_from_global_constraint_dof(const dof_id_type full_dof) const
{
  return libmesh_map_find(_full_to_reduced_constraint_dofs, full_dof);
}
 
}
 
#endif // LIBMESH_STATIC_CONDENSATION_DOF_MAP_H