Sub QUAD3D(XX1, XX2, SS)
    Call QGAUSX(DUM, XX1, XX2, SS)
End Sub
Function F(ZZ)
    Z = ZZ
    F = FUNC(X, Y, Z)
End Function
Function G(YY)
    Y = YY
    B1 = Z1(X, Y)
    B2 = Z2(X, Y)
    Call QGAUSZ(DUM, B1, B2, SS)
    G = SS
End Function
Function H(XX)
    X = XX
    A1 = Y1(X)
    A2 = Y2(X)
    Call QGAUSY(DUM, A1, A2, SS)
    H = SS
End Function