point in ellipse

I see many function for circle collision, but do not see any for ellipse.
Here is my version for Point / Ellipse:

```
function pointEllipse(px, py, cx, cy, r1, r2){
    var dx = px-cx;
    var dy = py-cy;
    return ((dx*dx)/(r1*r1)+(dy*dy)/(r2*r2)<=1);
}
```