tensor_product_polynomials_const.h

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// ---------------------------------------------------------------------
//
// Copyright (C) 2012 - 2020 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.md at
// the top level directory of deal.II.
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#ifndef dealii_tensor_product_polynomials_const_h
#define dealii_tensor_product_polynomials_const_h


#include <deal.II/base/config.h>

#include <deal.II/base/exceptions.h>
#include <deal.II/base/point.h>
#include <deal.II/base/polynomial.h>
#include <deal.II/base/tensor.h>
#include <deal.II/base/tensor_product_polynomials.h>
#include <deal.II/base/utilities.h>

#include <vector>

DEAL_II_NAMESPACE_OPEN


template <int dim>
class TensorProductPolynomialsConst : public ScalarPolynomialsBase<dim>
{
public:
  static const unsigned int dimension = dim;

  template <class Pol>
  TensorProductPolynomialsConst(const std::vector<Pol> &pols);

  void
  output_indices(std::ostream &out) const;

  void
  set_numbering(const std::vector<unsigned int> &renumber);

  const std::vector<unsigned int> &
  get_numbering() const;

  const std::vector<unsigned int> &
  get_numbering_inverse() const;

  void
  evaluate(const Point<dim> &           unit_point,
           std::vector<double> &        values,
           std::vector<Tensor<1, dim>> &grads,
           std::vector<Tensor<2, dim>> &grad_grads,
           std::vector<Tensor<3, dim>> &third_derivatives,
           std::vector<Tensor<4, dim>> &fourth_derivatives) const override;

  double
  compute_value(const unsigned int i, const Point<dim> &p) const;

  template <int order>
  Tensor<order, dim>
  compute_derivative(const unsigned int i, const Point<dim> &p) const;

  Tensor<1, dim>
  compute_grad(const unsigned int i, const Point<dim> &p) const;

  Tensor<2, dim>
  compute_grad_grad(const unsigned int i, const Point<dim> &p) const;

  unsigned int
  n() const;

  std::string
  name() const override;

  virtual std::unique_ptr<ScalarPolynomialsBase<dim>>
  clone() const override;

private:
  TensorProductPolynomials<dim> tensor_polys;

  std::vector<unsigned int> index_map;

  std::vector<unsigned int> index_map_inverse;
};

/* ---------------- template and inline functions ---------- */

#ifndef DOXYGEN

template <int dim>
template <class Pol>
inline TensorProductPolynomialsConst<dim>::TensorProductPolynomialsConst(
  const std::vector<Pol> &pols)
  : ScalarPolynomialsBase<dim>(1, Utilities::fixed_power<dim>(pols.size()) + 1)
  , tensor_polys(pols)
  , index_map(tensor_polys.n() + 1)
  , index_map_inverse(tensor_polys.n() + 1)
{}



template <int dim>
inline unsigned int
TensorProductPolynomialsConst<dim>::n() const
{
  return tensor_polys.n() + 1;
}



template <int dim>
inline const std::vector<unsigned int> &
TensorProductPolynomialsConst<dim>::get_numbering() const
{
  return index_map;
}


template <int dim>
inline const std::vector<unsigned int> &
TensorProductPolynomialsConst<dim>::get_numbering_inverse() const
{
  return index_map_inverse;
}


template <int dim>
inline std::string
TensorProductPolynomialsConst<dim>::name() const
{
  return "TensorProductPolynomialsConst";
}


template <>
inline unsigned int
TensorProductPolynomialsConst<0>::n() const
{
  return numbers::invalid_unsigned_int;
}


template <int dim>
template <int order>
Tensor<order, dim>
TensorProductPolynomialsConst<dim>::compute_derivative(
  const unsigned int i,
  const Point<dim> & p) const
{
  const unsigned int max_indices = tensor_polys.n();
  Assert(i <= max_indices, ExcInternalError());

  // treat the regular basis functions
  if (i < max_indices)
    return tensor_polys.template compute_derivative<order>(i, p);
  else
    // this is for the constant function
    return Tensor<order, dim>();
}


#endif // DOXYGEN
DEAL_II_NAMESPACE_CLOSE

#endif