code: def _compute_term_3_4(self, dists, C):
          
          cutoff = 6.056877878
          rhypo = dists.rhypo.copy()
          rhypo[rhypo <= cutoff] = cutoff
          return C['c3'] * np.log(rhypo) + C['c4'] * rhypo
docs: Compute term 3 and 4 in equation 1 page 1.