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             : 
       8             : #include "DataStructures/ModalVector.hpp"
       9             : #include "DataStructures/Tensor/Tensor.hpp"
      10             : #include "Utilities/TMPL.hpp"
      11             : 
      12             : namespace ylm {
      13             : /// @{
      14             : /*!
      15             :  * \brief Converts real spherical harmonic coefficients of degree l into a
      16             :  * symmetric trace-free tensor of rank l.
      17             :  *
      18             :  * \details Spherical harmonics of degree l are equivalent to symmetric
      19             :  * trace-free tensors of rank l. This equivalence and the transformation is
      20             :  * given e.g. in \cite Thorne1980, Eqs. (2.10) - (2.14). The conversion
      21             :  * coefficients are hard-coded to numerical precision and implemented up to
      22             :  * order l=2.
      23             :  *
      24             :  * The spherical harmonic coefficients are expected to be sorted with ascending
      25             :  * m, i.e. (-m, -m+1, ... , m)
      26             :  */
      27           1 : Scalar<double> ylm_to_stf_0(const ModalVector& l0_coefs);
      28             : 
      29             : template <typename Frame>
      30           1 : tnsr::i<double, 3, Frame> ylm_to_stf_1(const ModalVector& l1_coefs);
      31             : 
      32             : template <typename Frame>
      33           1 : tnsr::ii<double, 3, Frame> ylm_to_stf_2(const ModalVector& l2_coefs);
      34             : /// @}
      35             : }  // namespace ylm