code: def rhypo_to_rjb(rhypo, mag):
      
      epsilon = rhypo - (4.853 + 1.347E-6 * (mag ** 8.163))
      rjb = np.zeros_like(rhypo)
      idx = epsilon >= 3.
      rjb[idx] = np.sqrt((epsilon[idx] ** 2.) - 9.0)
      rjb[rjb < 0.0] = 0.0
      return rjb
docs: Converts hypocentral distance to an equivalent Joyner-Boore distance
      dependent on the magnitude