code: def _get_abc_helper(view_vector, sat_pos, ellipsoid):
      """Get a,b,c helper variables.
  
      Reference: Appendix E, Equation (26) in the GMS user guide.
      """
      flat2 = (1 - ellipsoid.flattening) ** 2
      ux, uy, uz = view_vector.x, view_vector.y, view_vector.z
      x, y, z = sat_pos.x, sat_pos.y, sat_pos.z
      a = flat2 * (ux**2 + uy**2) + uz**2
      b = flat2 * (x * ux + y * uy) + z * uz
      c = (
          flat2 * (x**2 + y**2 - ellipsoid.equatorial_radius**2)
          + z**2
      )
      return a, b, c
  
imports: from collections import namedtuple
  import dask.array
  import numba
  import numpy
  from satpy.utils import get_legacy_chunk_size
label_desc: Use image node_id 26 for calling a global function with example usage: _get_abc_helper(view_vector, sat_pos, ellipsoid) and returns: a,  b,  c