code: def geo2apex(self, glat, glon, height):
          
  
          glat = helpers.checklat(glat, name='glat')
  
          alat, alon = self._geo2apex(glat, glon, height)
  
          if np.any(np.float64(alat) == -9999):
              warnings.warn('Apex latitude set to -9999 where undefined '
                            '(apex height may be < reference height)')
  
          # if array is returned, dtype is object, so convert to float
          return np.float64(alat), np.float64(alon)
docs: Converts geodetic to modified apex coordinates.
  
          Parameters
          ==========
          glat : array_like
              Geodetic latitude
          glon : array_like
              Geodetic longitude
          height : array_like
              Altitude in km
  
          Returns
          =======
          alat : ndarray or float
              Modified apex latitude
          alon : ndarray or float
              Modified apex longitude