Line data    Source code

       1            0 : // Distributed under the MIT License.
       2              : // See LICENSE.txt for details.
       3              : 
       4              : #pragma once
       5              : 
       6              : #include "DataStructures/Tensor/Tensor.hpp"
       7              : #include "Utilities/Gsl.hpp"
       8              : #include "Utilities/Kokkos/KokkosMacros.hpp"
       9              : #include "Utilities/MakeWithValue.hpp"
      10              : 
      11              : /// @{
      12              : /*!
      13              :  * \ingroup GeneralRelativityGroup
      14              :  * \brief Computes trace of a rank 3 tensor, which is symmetric in its last two
      15              :  * indices, tracing the symmetric indices.
      16              :  *
      17              :  * \details For example, if \f$ T_{abc} \f$ is a tensor such that \f$T_{abc} =
      18              :  * T_{acb} \f$ then \f$ T_a = g^{bc}T_{abc} \f$ is computed, where \f$ g^{bc}
      19              :  * \f$ is the inverse metric.  Note that indices \f$a,b,c,...\f$ can represent
      20              :  * either spatial or spacetime indices, and can have either valence.  You may
      21              :  * have to add a new instantiation of this template if you need a new use case.
      22              :  *
      23              :  * These functions can be called in Kokkos kernels with `double`s.
      24              :  */
      25              : template <typename DataType, typename Index0, typename Index1>
      26            1 : KOKKOS_FUNCTION void trace_last_indices(
      27              :     gsl::not_null<Tensor<DataType, Symmetry<1>, index_list<Index0>>*>
      28              :         trace_of_tensor,
      29              :     const Tensor<DataType, Symmetry<2, 1, 1>,
      30              :                  index_list<Index0, Index1, Index1>>& tensor,
      31              :     const Tensor<DataType, Symmetry<1, 1>,
      32              :                  index_list<change_index_up_lo<Index1>,
      33              :                             change_index_up_lo<Index1>>>& metric);
      34              : 
      35              : SPECTRE_KOKKOS_DISABLE_EXEC_CHECK
      36              : template <typename DataType, typename Index0, typename Index1>
      37              : KOKKOS_FUNCTION Tensor<DataType, Symmetry<1>, index_list<Index0>>
      38            1 : trace_last_indices(
      39              :     const Tensor<DataType, Symmetry<2, 1, 1>,
      40              :                  index_list<Index0, Index1, Index1>>& tensor,
      41              :     const Tensor<DataType, Symmetry<1, 1>,
      42              :                  index_list<change_index_up_lo<Index1>,
      43              :                             change_index_up_lo<Index1>>>& metric) {
      44              :   Tensor<DataType, Symmetry<1>, index_list<Index0>> trace_of_tensor{};
      45              :   trace_last_indices(make_not_null(&trace_of_tensor), tensor, metric);
      46              :   return trace_of_tensor;
      47              : }
      48              : /// @}
      49              : 
      50              : /// @{
      51              : /*!
      52              :  * \ingroup GeneralRelativityGroup
      53              :  * \brief Computes trace of a rank-2 symmetric tensor.
      54              :  * \details Computes \f$g^{ab}T_{ab}\f$ or \f$g_{ab}T^{ab}\f$ where \f$(a,b)\f$
      55              :  * can be spatial or spacetime indices.
      56              :  *
      57              :  * These functions can be called in Kokkos kernels with `double`s.
      58              :  */
      59              : template <typename DataType, typename Index0>
      60            1 : KOKKOS_FUNCTION void trace(
      61              :     gsl::not_null<Scalar<DataType>*> trace,
      62              :     const Tensor<DataType, Symmetry<1, 1>, index_list<Index0, Index0>>& tensor,
      63              :     const Tensor<DataType, Symmetry<1, 1>,
      64              :                  index_list<change_index_up_lo<Index0>,
      65              :                             change_index_up_lo<Index0>>>& metric);
      66              : 
      67              : SPECTRE_KOKKOS_DISABLE_EXEC_CHECK
      68              : template <typename DataType, typename Index0>
      69            1 : KOKKOS_FUNCTION Scalar<DataType> trace(
      70              :     const Tensor<DataType, Symmetry<1, 1>, index_list<Index0, Index0>>& tensor,
      71              :     const Tensor<DataType, Symmetry<1, 1>,
      72              :                  index_list<change_index_up_lo<Index0>,
      73              :                             change_index_up_lo<Index0>>>& metric) {
      74              :   Scalar<DataType> trace{};
      75              :   ::trace(make_not_null(&trace), tensor, metric);
      76              :   return trace;
      77              : }
      78              : /// @}