Don, Wow! I had no idea that Sparse could do that. I've never bothered to read the full Dictionary entry on Sparse, mostly because I have never needed to use sparse arrays. I didn't realize that $. was applicable to normal arrays, or that it could take a left argument. Skip On Fri, Nov 30, 2018 at 1:04 PM Don Guinn <donguinn at gmail.com> wrote: > Or do >> 4 $.$.a > . ormation about J forums see http://www.jsoftware.com/forums.htm