Private Sub Command1_Click()
    'PROGRAM D10R4
    'Driver for routine RTBIS
    N = 100
    NBMAX = 20
    X1 = 1#
    X2 = 50#
    Dim XB1(20), XB2(20)
    NB = NBMAX
    Call ZBRAK(X1, X2, N, XB1(), XB2(), NB)
    Print
    Print Tab(5); "Roots of BESSJ0:"
    Print
    Print "                  x           F(x)"
    For I = 1 To NB
        XACC = (0.000001) * (XB1(I) + XB2(I)) / 2#
        ROOT = RTBIS(XB1(I), XB2(I), XACC)
        Print Tab(3); "Root"; Format$(I, "##");
        Print Tab(15); Format$(ROOT, "##.###000");
        Print Tab(30); Format$(BESSJ0(ROOT), ".##00E+00")
    Next I
End Sub
Function FUNC(X)
    FUNC = BESSJ0(X)
End Function