Line data    Source code

       1           0 : // Distributed under the MIT License.
       2             : // See LICENSE.txt for details.
       3             : 
       4             : #pragma once
       5             : 
       6             : namespace CurvedScalarWave::Worldtube {
       7             : 
       8             : namespace detail {
       9             : 
      10             : void check_alpha(double alpha);
      11             : 
      12             : void check_delta(double delta);
      13             : }  // namespace detail
      14             : 
      15             : /*!
      16             :  * \brief A smoothly broken power law that falls off to a constant value
      17             :  * for larger radii.
      18             :  *
      19             :  * \details The function is given by Eq. (3) of \cite Wittek:2024pis
      20             :  *
      21             :  * \begin{equation}
      22             :  * f(r) = R_\infty \left(\frac{r}{r_b}\right)^{\alpha} \left( 1 +
      23             :  * \left(\frac{r}{r_b}\right)^{1 / \Delta}\right)^{-\alpha\Delta}.
      24             :  * \end{equation}
      25             :  *
      26             :  * For radii $r \ll r_b$, the function obeys the power law $f(r) \propto
      27             :  * r^{\alpha}$. For radii $r \gg r_b$, the function asymptotes to $R_\infty$.
      28             :  * The parameter $\Delta$ determines the width of the transition region with a
      29             :  * larger value of $\Delta$ leading to a more gradual transition.
      30             :  *
      31             :  * This function is used to control the worldtube radius for more eccentric
      32             :  * orbits so the radius does not grow too large during the apoapsis passage
      33             :  * as this does not lead to performance gains and can cause problems with the
      34             :  * domain.
      35             :  */
      36           1 : double smooth_broken_power_law(double orbit_radius, double alpha,
      37             :                                double radius_at_inf, double rb, double delta);
      38             : /*!
      39             :  * \brief Returns the analytical derivative of `smooth_broken_power_law`.
      40             :  */
      41           1 : double smooth_broken_power_law_derivative(double orbit_radius, double alpha,
      42             :                                           double radius_at_inf, double rb,
      43             :                                           double delta);
      44             : }  // namespace CurvedScalarWave::Worldtube