@ red Aσ, there is an unexplained error ?
Can some collab contribute to doctor the fault ?

Thanks, Jean

Ellipse Sigma Fit.sm (30 KiB) downloaded 62 time(s).

For some reason, StdDev has troubles working with this symbolical array.
Please use eval() to get numerical array:



BTW, lenghty calculations are manyfold faster if you modify Ellipse definition block like this:

Thanks Mike for doctoring .

Jean