Help Plotting an Ellipse from X,Y data

I am looking for help on making an ellipse on my XY plot. I want my ellipse to cover 95% of the data but I am having trouble doing so.

X data = FCOPX

Y data = FCOPY

Any help would be great thank you.

Answer 1

[Matt J]

a=3; b=2;  %Major/minor ellipse radii

plot(rand(1,5)); hold on; axis equal
ellipse = translate( scale(nsidedpoly(1000),[a,b])  , [mean(xlim), mean(ylim)] ); 
plot(ellipse); hold off