docs: def get_tilt(dec_geo, inc_geo, dec_tilt, inc_tilt):
      """
      Function to return the dip direction and dip that would yield the tilt
      corrected direction if applied to the uncorrected direction (geographic
      coordinates)
  
      Parameters
      ----------
      dec_geo : declination in geographic coordinates
      inc_geo : inclination in geographic coordinates
      dec_tilt : declination in tilt-corrected coordinates
      inc_tilt : inclination in tilt-corrected coordinates
  
      Returns
      -------
      DipDir, Dip : tuple of dip direction and dip
      """
  # strike is horizontal line equidistant from two input directions
      SCart = [0, 0, 0]  # cartesian coordites of Strike
      SCart[2] = 0.  # by definition
      # cartesian coordites of Geographic D
      GCart = dir2cart([dec_geo, inc_geo, 1.])
      TCart = dir2cart([dec_tilt, inc_tilt, 1.])  # cartesian coordites of Tilt D
      X = old_div((TCart[1] - GCart[1]), (GCart[0] - TCart[0]))
      SCart[1] = np.sqrt(old_div(1, (X**2 + 1.)))
      SCart[0] = SCart[1] * X
      SDir = cart2dir(SCart)
      DipDir = (SDir[0] - 90.) % 360.
      DipDir = (SDir[0] + 90.) % 360.
  # D is creat circle distance between geo direction and strike
  # theta is GCD between geo and tilt (on unit sphere).  use law of cosines
  # to get small cirlce between geo and tilt (dip)
      cosd = GCart[0] * SCart[0] + GCart[1] * \
          SCart[1]  # cosine of angle between two
      d = np.arccos(cosd)
      cosTheta = GCart[0] * TCart[0] + GCart[1] * TCart[1] + GCart[2] * TCart[2]
      Dip = (old_div(180., np.pi)) * \
          np.arccos(-(old_div((cosd**2 - cosTheta), np.sin(d)**2)))
      if Dip > 90:
          Dip = -Dip
      return DipDir, Dip