Line data    Source code

       1           0 : // Distributed under the MIT License.
       2             : // See LICENSE.txt for details.
       3             : 
       4             : #pragma once
       5             : 
       6             : #include <cstddef>
       7             : #include <vector>
       8             : 
       9             : #include "DataStructures/DataVector.hpp"
      10             : 
      11             : namespace io {
      12             : 
      13             : /*!
      14             :  * \brief Compute \f$\zeta\f$ analytically from the tabulated free-energy
      15             :  * derivatives of a CompOSE 3D EoS.
      16             :  *
      17             :  * Computes
      18             :  * \f[
      19             :  * \zeta = \left.\frac{\partial p}{\partial Y_e}\right|_{\rho,\epsilon}
      20             :  *       = \left.\frac{\partial(p,\epsilon) / \partial(T,Y_e)}
      21             :  *                    {\partial(Y_e,\epsilon) / \partial(T,Y_e)}\right|_{n_b}
      22             :  *       = p_{Y_e} - p_T\,\frac{\epsilon_{Y_e}}{\epsilon_T}
      23             :  * \f]
      24             :  * at fixed baryon density (\f$\rho \propto n_b\f$), where every partial
      25             :  * derivative is evaluated analytically from the free energy per baryon
      26             :  * \f$\mathcal{F}\f$. With \f$p = n_b^2 \mathcal{F}_{n_b}\f$ and
      27             :  * \f$\epsilon = \mathcal{F} - T\mathcal{F}_T\f$ this gives
      28             :  * \f{align}{
      29             :  * p_{Y_e}      &= n_b^2\,\mathcal{F}_{n_b Y_e}, &
      30             :  * p_T          &= n_b^2\,\mathcal{F}_{n_b T}, \\
      31             :  * \epsilon_{Y_e} &= \mathcal{F}_{Y_e} - T\,\mathcal{F}_{T Y_e}, &
      32             :  * \epsilon_T     &= -T\,\mathcal{F}_{T T}.
      33             :  * \f}
      34             :  * The neutron-mass scaling and rest-mass offset between CompOSE's stored
      35             :  * \f$\epsilon\f$ and \f$\mathcal{F} - T\mathcal{F}_T\f$ cancel because only the
      36             :  * ratio \f$\epsilon_{Y_e}/\epsilon_T\f$ enters, so the result is in units of
      37             :  * MeV/fm\f$^3\f$ per unit \f$Y_e\f$ (matching the tabulated pressure).
      38             :  *
      39             :  * The arguments `d2f_dt2`, `d2f_dt_dnb`, `d2f_dt_dye`, `d2f_dnb_dye`, and
      40             :  * `df_dye` are the CompOSE free-energy derivatives \f$\mathcal{F}_{TT}\f$,
      41             :  * \f$\mathcal{F}_{T n_b}\f$, \f$\mathcal{F}_{T Y_e}\f$,
      42             :  * \f$\mathcal{F}_{n_b Y_e}\f$, and \f$\mathcal{F}_{Y_e}\f$ (Table 7.3
      43             :  * derivative indices 3, 4, 5, 8, and 9). The `number_density_grid` and
      44             :  * `temperature_grid` hold the per-node \f$n_b\f$ (in fm\f$^{-3}\f$) and \f$T\f$
      45             :  * (in MeV).
      46             :  *
      47             :  * The CompOSE table is flattened in file order, with \f$Y_e\f$ varying
      48             :  * fastest, then \f$n_b\f$, then \f$T\f$: idx = (iT * nN + in) * nYe + iYe.
      49             :  */
      50           1 : DataVector compute_zeta_from_free_energy_derivatives(
      51             :     const DataVector& d2f_dt2, const DataVector& d2f_dt_dnb,
      52             :     const DataVector& d2f_dt_dye, const DataVector& d2f_dnb_dye,
      53             :     const DataVector& df_dye, const std::vector<double>& number_density_grid,
      54             :     const std::vector<double>& temperature_grid, size_t number_density_points,
      55             :     size_t temperature_points, size_t electron_fraction_points);
      56             : 
      57             : }  // namespace io