code: def _get_smr_coeffs(self, C, C_SITE, idx, n_sites, sa_rock):
          
          # Get SR
          sreff = np.zeros(n_sites)
          sreffc = np.zeros(n_sites)
          f_sr = np.zeros(n_sites)
          for i in range(1, 5):
              sreff[idx[i]] += (np.exp(sa_rock[idx[i]]) * self.IMF[i])
              sreffc[idx[i]] += (C_SITE["Src1D{:g}".format(i)] * self.IMF[i])
              # Get f_SR
              f_sr[idx[i]] += C_SITE["fsr{:g}".format(i)]
          return sreff, sreffc, f_sr
docs: Returns the SReff and SReffC terms needed for equation 14 and 15