Sorry, you meant standard deviation, not variance. > On Jul 16, 2020, at 2:28 PM, Lucier, Bradley J <xxxxxx@purdue.edu> wrote: > > I think you mean sqrt(A), etc. Brad > >> On Jul 16, 2020, at 2:14 PM, Linas Vepstas <xxxxxx@gmail.com> wrote: >> >> So, if the ellipse major axis lengths are A,B,C... then generate X,Y,Z with widths A,B,C..