tensor_function.h

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// ------------------------------------------------------------------------
//
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 1999 - 2023 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Part of the source code is dual licensed under Apache-2.0 WITH
// LLVM-exception OR LGPL-2.1-or-later. Detailed license information
// governing the source code and code contributions can be found in
// LICENSE.md and CONTRIBUTING.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/enable_observer_pointer.h>
#include <deal.II/base/exceptions.h>
#include <deal.II/base/function.h>
#include <deal.II/base/function_time.h>
#include <deal.II/base/observer_pointer.h>
#include <deal.II/base/point.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 EnableObserverPointer
{
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