incremental_function.h

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// ------------------------------------------------------------------------
//
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2018 - 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_incremental_function_h
#define dealii_incremental_function_h
 
 
#include <deal.II/base/config.h>
 
#include <deal.II/base/function.h>
#include <deal.II/base/mutex.h>
 
#include <deal.II/lac/vector.h>
 
 
DEAL_II_NAMESPACE_OPEN
 
// Forward declaration
#ifndef DOXYGEN
template <typename number>
class Vector;
#endif
 
namespace Functions
{
  template <int dim, typename RangeNumberType = double>
  class IncrementalFunction : public Function<dim, RangeNumberType>
  {
  public:
    static constexpr unsigned int dimension = dim;
 
    using time_type = typename Function<dim, RangeNumberType>::time_type;
 
    IncrementalFunction(Function<dim, RangeNumberType> &base);
 
    virtual RangeNumberType
    value(const Point<dim> &p, const unsigned int component = 0) const override;
 
    virtual void
    vector_value(const Point<dim>        &p,
                 Vector<RangeNumberType> &values) const override;
 
    void
    set_decrement(const time_type delta_t);
 
  private:
    Function<dim, RangeNumberType> &base;
 
    time_type delta_t;
 
    mutable Vector<RangeNumberType> values_old;
 
    mutable Threads::Mutex mutex;
  };
 
} // namespace Functions
 
 
DEAL_II_NAMESPACE_CLOSE
 
#endif