Private Sub cmdDraw_Click()
Const PI = 3.14159265
Dim A As Single
Dim B As Single
Dim theta As Single
Dim dtheta As Single

    A = CSng(txtA.Text)
    B = CSng(txtB.Text)
    picGraph.ScaleLeft = 0
    picGraph.ScaleWidth = 4 * PI
    picGraph.ScaleTop = 2
    picGraph.ScaleHeight = -4
    picGraph.AutoRedraw = True

    theta = 0
    picGraph.Cls
    picGraph.CurrentX = theta
    picGraph.CurrentY = Sin(A * theta) + Sin(B * theta)

    dtheta = 4 * PI / picGraph.ScaleX(picGraph.ScaleWidth, _
        picGraph.ScaleMode, vbPixels)
    Do While theta <= 4 * PI + dtheta / 2
        picGraph.Line -(theta, Sin(A * theta) + Sin(B * _
            theta))
        theta = theta + dtheta
    Loop
End Sub