function calculatePoint(rw,rh,cx,cy,p1,p2) {
    assert(rh >= rw);

    // Calculate rd*(x^2) + y^2 = rr
    rr = rh^2
        ==> 4
    rd = (rh / rw)^2

    // Translate the points to the center so the ellipse is at 0,0
    p1.x -= cx;
    p1.y -= cy;
    p2.x -= cx;
    p2.y -= cy;

    // Calculate the vector for p1 - p2 (from the tanget to the source)
    v.x = p1.x - p2.x
    v.y = p1.y - p2.y

    // Calculate the vector of the tangent at p2
    n.x = -rd * p2.x
    n.y = p2.y

    // Normalise that vector
    l = sqrt((n.x*n.x)+(n.y*n.y));
    n.x /= l;
    n.y /= l;

    // Calculate the dot product (used in the reflection calculation)
    d = (v.x*n.x) + (v.y*n.y)

    // Calculate the reflection
    // Thanks to http://www.actionscript.org/forums/showthread.php3?t=176052 for this
    r.x = v.x - (2 * d * n.x)
    r.y = v.y - (2 * d * n.y)

    // Calculate how much y will increase by every time x increases by 1
    r.y /= r.x;
    r.x = 1;

    // now y = p2.y - (r.y)x
    // plug this into rd*(x^2) + y^2 = rr
    // doing so ends up with the following ax2 + bx + c
    // Valules worked out by expanding rdx2 + (b + cx)(b + cx) - rr = 0

    a = (rd + (r.y^2))
    b = (2 * r.y * p2.y)
    c = ((p2.y^2) - rr)

    // Preform half the quadratic equation to get x
    p3.x = (-b + sqrt(b^2 - (4*a*c))) / (2*a)

    // Plug this new x in to rd*(x^2) + y^2 = rr to get y
    p3.y = sqrt(rr - rd*(p3.x^2))

    /// Translate the points back so the ellipse is not in the center anymore.
    p3.x += cx;
    p3.y += cy;

    // Return the newly calculated point.
    return p3;
}