point detection against ellipses

hi there,
I'm trying to find a method to test if a point is within a given ellipse, and after an initial look at the information I could find, it's not looking easy - does anyone know of a (fast) way to determine this?

thanks

Try:

pointWithinEllipse = function ( ex , ey , ea , eb , px , py ) {

var dx = px - ex;
var dy = py - ey;

return (dx*dx)/(ea*ea) + (dy*dy)/(eb*eb) <= 1;

}

ex,ey = position ellipse
ea,eb = radiants of ellipse
px,py = position of point

returns true, if Point is within ellipse or exact on the outline else false

great - thanks for that!