code: def _compute_mean(self, C, g, mag, hypo_depth, dists, imt):
          
  
          delta = 0.00750 * 10 ** (0.507 * mag)
  
          # computing R for different values of mag
          if mag < 6.5:
              R = np.sqrt(dists.rhypo ** 2 + delta ** 2)
          else:
              R = np.sqrt(dists.rrup ** 2 + delta ** 2)
  
          mean = (
              # 1st term
              C['c1'] + C['c2'] * mag +
              # 2nd term
              C['c3'] * R -
              # 3rd term
              C['c4'] * np.log10(R) +
              # 4th term
              C['c5'] * hypo_depth
          )
          # convert from base 10 to base e
          if imt == PGV():
              mean = np.log(10 ** mean)
          else:
              # convert from cm/s**2 to g
              mean = np.log((10 ** mean) * 1e-2 / g)
          return mean
docs: Compute mean according to equation on Table 2, page 2275.