exact_error_estimator.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_EXACT_ERROR_ESTIMATOR_H
#define LIBMESH_EXACT_ERROR_ESTIMATOR_H
 
// Local Includes
#include "libmesh/error_estimator.h"
#include "libmesh/function_base.h"
#include "libmesh/vector_value.h"
#include "libmesh/tensor_value.h"
 
// C++ includes
#include <cstddef>
#include <string>
#include <vector>
 
namespace libMesh
{
 
// Forward Declarations
class Elem;
template <typename T> class FEGenericBase;
typedef FEGenericBase<Real> FEBase;
class MeshFunction;
class Point;
class Parameters;
template <typename T> class DenseVector;
 
class ExactErrorEstimator : public ErrorEstimator
{
public:
 
  ExactErrorEstimator();
 
  ExactErrorEstimator (const ExactErrorEstimator &) = delete;
  ExactErrorEstimator & operator= (const ExactErrorEstimator &) = delete;
 
  ExactErrorEstimator (ExactErrorEstimator &&) = default;
  ExactErrorEstimator & operator= (ExactErrorEstimator &&) = default;
  virtual ~ExactErrorEstimator() = default;
 
  void attach_exact_values (std::vector<FunctionBase<Number> *> f);
 
  void attach_exact_value (unsigned int sys_num,
                           FunctionBase<Number> * f);
 
  typedef Number (*ValueFunctionPointer)(const Point & p,
                                         const Parameters & Parameters,
                                         const std::string & sys_name,
                                         const std::string & unknown_name);
  void attach_exact_value (ValueFunctionPointer fptr);
 
  void attach_exact_derivs (std::vector<FunctionBase<Gradient> *> g);
 
  void attach_exact_deriv (unsigned int sys_num,
                           FunctionBase<Gradient> * g);
 
  typedef Gradient (*GradientFunctionPointer)(const Point & p,
                                              const Parameters & parameters,
                                              const std::string & sys_name,
                                              const std::string & unknown_name);
  void attach_exact_deriv (GradientFunctionPointer gptr);
 
  void attach_exact_hessians (std::vector<FunctionBase<Tensor> *> h);
 
  void attach_exact_hessian (unsigned int sys_num,
                             FunctionBase<Tensor> * h);
 
  typedef Tensor (*HessianFunctionPointer)(const Point & p,
                                           const Parameters & parameters,
                                           const std::string & sys_name,
                                           const std::string & unknown_name);
  void attach_exact_hessian (HessianFunctionPointer hptr);
 
  void attach_reference_solution (EquationSystems * es_fine);
 
  void extra_quadrature_order (const int extraorder)
  { _extra_order = extraorder; }
 
  // Bring the base class functionality into the name lookup
  // procedure.  This allows for alternative calling formats
  // defined in the base class.  Thanks Wolfgang.
  // GCC 2.95.3 cannot compile such code.  Since it was not really
  // essential to the functioning of this class, it's been removed.
  // using ErrorEstimator::estimate_error;
 
  virtual void estimate_error (const System & system,
                               ErrorVector & error_per_cell,
                               const NumericVector<Number> * solution_vector = nullptr,
                               bool estimate_parent_error = false) override;
 
  virtual ErrorEstimatorType type() const override;
 
private:
 
  ValueFunctionPointer _exact_value;
 
  GradientFunctionPointer _exact_deriv;
 
  HessianFunctionPointer _exact_hessian;
 
  std::vector<std::unique_ptr<FunctionBase<Number>>> _exact_values;
 
  std::vector<std::unique_ptr<FunctionBase<Gradient>>> _exact_derivs;
 
  std::vector<std::unique_ptr<FunctionBase<Tensor>>> _exact_hessians;
 
  EquationSystems * _equation_systems_fine;
 
  Real find_squared_element_error (const System & system,
                                   const std::string & var_name,
                                   const Elem * elem,
                                   const DenseVector<Number> & Uelem,
                                   FEBase * fe,
                                   MeshFunction * fine_values) const;
 
  void clear_functors ();
 
  int _extra_order;
};
 
 
} // namespace libMesh
 
#endif // LIBMESH_EXACT_ERROR_ESTIMATOR_H