Sorting a list with `lambda x: x[0]` is actually really slow... also there is no way to access the ellipse parameters in an efficient way and use them in a vectorized manner.

My suggestion: use separate lists for acc, y0, x0, etc. and `return numpy.array(accums), numpy.array(y0s), ....`.

Alternatively (my favorite): Return a combined `numpy.recarray`, which also allows sorting the array easily.