Sub QSIMP(A, B, S)
    EPS = 0.000001
    JMAX = 20
    OST = -1E+30
    OS = -1E+30
    For J = 1 To JMAX
        Call TRAPZD(A, B, ST, J)
        S = (4# * ST - OST) / 3#
        If Abs(S - OS) < EPS * Abs(OS) Then Exit Sub
        OS = S
        OST = ST
    Next J
    Print "Too many steps."
End Sub