Sub LOCATE(XX(), N, X, J%)
    JL = 0
    JU = N + 1
10  If JU - JL > 1 Then
        JM = (JU + JL) / 2
        If XX(N) > XX(1) Eqv X > XX(JM) Then
            JL = JM
        Else
            JU = JM
        End If
        GoTo 10
    End If
    J% = JL
End Sub