function_bessel.h

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// -----------------------------------------------------------------------------
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception OR LGPL-2.1-or-later
// Copyright (C) 2010 - 2025 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Detailed license information governing the source code and contributions
// can be found in LICENSE.md and CONTRIBUTING.md at the top level directory.
//
// -----------------------------------------------------------------------------
 
#ifndef dealii_function_bessel_h
#define dealii_function_bessel_h
 
 
#include <deal.II/base/config.h>
 
#include <deal.II/base/function.h>
#include <deal.II/base/point.h>
 
#include <vector>
 
 
DEAL_II_NAMESPACE_OPEN
 
namespace Functions
{
  template <int dim>
  class Bessel1 : public Function<dim>
  {
  public:
    Bessel1(const unsigned int order,
            const double       wave_number,
            const Point<dim>   center = Point<dim>());
 
    virtual double
    value(const Point<dim>  &points,
          const unsigned int component = 0) const override;
 
    virtual void
    value_list(const std::vector<Point<dim>> &points,
               std::vector<double>           &values,
               const unsigned int             component = 0) const override;
 
    virtual Tensor<1, dim>
    gradient(const Point<dim>  &p,
             const unsigned int component = 0) const override;
 
    virtual void
    gradient_list(const std::vector<Point<dim>> &points,
                  std::vector<Tensor<1, dim>>   &gradients,
                  const unsigned int             component = 0) const override;
 
  private:
    unsigned int order;
    double       wave_number;
    Point<dim>   center;
  };
} // namespace Functions
 
DEAL_II_NAMESPACE_CLOSE
 
#endif