code: def get_distance_term(self, C, rrup):
          
          f_p = C["c1"] * rrup
          idx = np.logical_and(rrup > self.CONSTANTS["r1"],
                               rrup <= self.CONSTANTS["r2"])
          f_p[idx] = (C["c1"] * self.CONSTANTS["r1"]) +\
              C["c2"] * (rrup[idx] - self.CONSTANTS["r1"])
          idx = rrup > self.CONSTANTS["r2"]
          f_p[idx] = C["c1"] * self.CONSTANTS["r1"] +\
              C["c2"] * (self.CONSTANTS["r2"] - self.CONSTANTS["r1"]) +\
              C["c3"] * (rrup[idx] - self.CONSTANTS["r2"])
          return f_p
docs: Returns the distance scaling term in equation 7