code: def _compute_term_2(self, C, mag, R):
          
          return (
              (C['a8'] + C['a9'] * mag + C['a10'] * np.power(mag, 2) +
               C['a11'] * np.power(mag, 3)) * R
          )
docs: (a8 + a9.*M + a10.*M.*M + a11.*M.*M.*M).*d(r)