Function ROFUNC(B)
    N1 = NDATAT + 1
    NML = N1 / 2
    NMH = N1 - NML
    For J = 1 To NDATAT
        ARR(J) = YT(J) - B * XT(J)
    Next J
    Call SORT(NDATAT, ARR())
    AA = 0.5 * (ARR(NML) + ARR(NMH))
    Sum = 0#
    ABDEVT = 0#
    For J = 1 To NDATAT
        D = YT(J) - (B * XT(J) + AA)
        ABDEVT = ABDEVT + Abs(D)
        Sum = Sum + XT(J) * Sgn(D)
    Next J
    ROFUNC = Sum
End Function