code: def _get_phis(window_size, length):
      phis = np.zeros(length)
      for i in range(int(length / 2)):
          phis[i * 2] += math.cos(2 * math.pi * (-i) / window_size)
          phis[i * 2 + 1] += -math.sin(2 * math.pi * (-i) / window_size)
      return phis
  
file_path: sktime/sktime/transformations/panel/dictionary_based/_sfa_numba.py
imports: import math
  import numpy
  from sktime.utils.numba.njit import njit
label_desc: Use image node_id 2 for calling a global function with example usage: _get_phis(window_size, length) and returns: phis