auto_derivative_function.h

// ---------------------------------------------------------------------
//
// Copyright (C) 2001 - 2017 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, 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.
// The full text of the license can be found in the file LICENSE at
// the top level of the deal.II distribution.
//
// ---------------------------------------------------------------------

#ifndef dealii_auto_derivative_function_h
#define dealii_auto_derivative_function_h


#include <deal.II/base/exceptions.h>
#include <deal.II/base/function.h>

DEAL_II_NAMESPACE_OPEN

template <int dim>
class AutoDerivativeFunction : public Function<dim>
{
public:

  enum DifferenceFormula
  {
    Euler,
    UpwindEuler,
    FourthOrder
  };

  AutoDerivativeFunction (const double h,
                          const unsigned int n_components = 1,
                          const double       initial_time = 0.0);

  virtual ~AutoDerivativeFunction () = default;

  void set_formula (const DifferenceFormula formula = Euler);

  void set_h (const double h);

  virtual Tensor<1,dim> gradient (const Point<dim>   &p,
                                  const unsigned int  component = 0) const;

  virtual void vector_gradient (const Point<dim>            &p,
                                std::vector<Tensor<1,dim> > &gradients) const;

  virtual void gradient_list (const std::vector<Point<dim> > &points,
                              std::vector<Tensor<1,dim> >    &gradients,
                              const unsigned int              component = 0) const;

  virtual void vector_gradient_list (const std::vector<Point<dim> > &points,
                                     std::vector<std::vector<Tensor<1,dim> > > &gradients) const;

  static
  DifferenceFormula
  get_formula_of_order (const unsigned int ord);


private:

  double h;

  std::vector<Tensor<1,dim> > ht;

  DifferenceFormula formula;
};


DEAL_II_NAMESPACE_CLOSE

#endif