function_derivative.h

// ---------------------------------------------------------------------
//
// Copyright (C) 2000 - 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_function_derivative_h
#define dealii_function_derivative_h

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

DEAL_II_NAMESPACE_OPEN


template <int dim>
class FunctionDerivative : public AutoDerivativeFunction<dim>
{
public:
  FunctionDerivative (const Function<dim> &f,
                      const Point<dim>    &direction,
                      const double         h = 1.e-6);

  FunctionDerivative (const Function<dim>            &f,
                      const std::vector<Point<dim> > &direction,
                      const double                    h = 1.e-6);

  void set_formula (typename AutoDerivativeFunction<dim>::DifferenceFormula formula
                    = AutoDerivativeFunction<dim>::Euler);
  void set_h (const double h);

  virtual double value (const Point<dim> &p,
                        const unsigned int component = 0) const;

  virtual void vector_value(const Point<dim> &p,
                            Vector<double> &value) const;

  virtual void value_list (const std::vector<Point<dim> > &points,
                           std::vector<double>            &values,
                           const unsigned int              component = 0) const;

  std::size_t memory_consumption () const;

private:
  const Function<dim> &f;

  double h;

  typename AutoDerivativeFunction<dim>::DifferenceFormula formula;

  std::vector<Tensor<1,dim> > incr;
};

DEAL_II_NAMESPACE_CLOSE

#endif