code: def _get_distance_segment_coefficients(self, rval):
          
          # Get distance segment ends
          nsites = len(rval)
          # Equation 12a
          f_0 = np.log10(self.CONSTS["r0"] / rval)
          f_0[rval > self.CONSTS["r0"]] = 0.0
  
          # Equation 12b
          f_1 = np.log10(rval)
          f_1[rval > self.CONSTS["r1"]] = np.log10(self.CONSTS["r1"])
          # Equation 12c
          f_2 = np.log10(rval / self.CONSTS["r2"])
          f_2[rval <= self.CONSTS["r2"]] = 0.0
          return f_0, f_1, f_2
docs: Returns the coefficients describing the distance attenuation shape
          for three different distance bins, equations 12a - 12c