tensor_function.h

// ---------------------------------------------------------------------
//
// Copyright (C) 1999 - 2018 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.
//
// ---------------------------------------------------------------------

#ifndef dealii_tensor_function_h
#define dealii_tensor_function_h


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

#include <deal.II/base/exceptions.h>
#include <deal.II/base/function.h>
#include <deal.II/base/function_time.h>
#include <deal.II/base/point.h>
#include <deal.II/base/smartpointer.h>
#include <deal.II/base/subscriptor.h>

#include <vector>

DEAL_II_NAMESPACE_OPEN

template <int rank, int dim, typename Number = double>
class TensorFunction
  : public FunctionTime<typename numbers::NumberTraits<Number>::real_type>,
    public Subscriptor
{
public:
  using value_type = Tensor<rank, dim, Number>;

  using gradient_type = Tensor<rank + 1, dim, Number>;

  using time_type = typename FunctionTime<
    typename numbers::NumberTraits<Number>::real_type>::time_type;

  TensorFunction(const time_type initial_time = time_type(0.0));

  virtual ~TensorFunction() override = default;

  virtual value_type
  value(const Point<dim> &p) const;

  virtual void
  value_list(const std::vector<Point<dim>> &points,
             std::vector<value_type> &      values) const;

  virtual gradient_type
  gradient(const Point<dim> &p) const;

  virtual void
  gradient_list(const std::vector<Point<dim>> &points,
                std::vector<gradient_type> &   gradients) const;
};



template <int rank, int dim, typename Number = double>
class ConstantTensorFunction : public TensorFunction<rank, dim, Number>
{
public:
  using time_type = typename TensorFunction<rank, dim, Number>::time_type;

  ConstantTensorFunction(const ::Tensor<rank, dim, Number> &value,
                         const time_type initial_time = 0.0);

  virtual ~ConstantTensorFunction() override = default;

  virtual typename ::TensorFunction<rank, dim, Number>::value_type
  value(const Point<dim> &p) const override;

  virtual void
  value_list(
    const std::vector<Point<dim>> &points,
    std::vector<typename ::TensorFunction<rank, dim, Number>::value_type>
      &values) const override;

  virtual typename ::TensorFunction<rank, dim, Number>::gradient_type
  gradient(const Point<dim> &p) const override;

  virtual void
  gradient_list(
    const std::vector<Point<dim>> &points,
    std::vector<
      typename ::TensorFunction<rank, dim, Number>::gradient_type>
      &gradients) const override;

private:
  const ::Tensor<rank, dim, Number> _value;
};



template <int rank, int dim, typename Number = double>
class ZeroTensorFunction : public ConstantTensorFunction<rank, dim, Number>
{
public:
  using time_type =
    typename ConstantTensorFunction<rank, dim, Number>::time_type;

  ZeroTensorFunction(const time_type initial_time = 0.0);
};


DEAL_II_NAMESPACE_CLOSE

#endif