Sub QTRAP(A, B, S)
    EPS = 0.000001
    JMAX = 20
    OLDS = -1E+30
    For J = 1 To JMAX
        Call TRAPZD(A, B, S, J)
        If Abs(S - OLDS) < EPS * Abs(OLDS) Then Exit Sub
        OLDS = S
    Next J
    Print "Too many steps."
End Sub