code: def _compute_mean(self, rup, dists, coeffs):
          
  
          ln_p = coeffs['c1'] + coeffs['c2']*rup.mag + \
              coeffs['c3']*(self.CONSTS['ref_mag'] - rup.mag)**3 +\
              coeffs['c4']*np.log(dists.rrup +
                                  coeffs['c5']*np.exp(coeffs['c6']*rup.mag))
  
          return ln_p
docs: Evaluate equation (11) on p. 484.