Ok, thanks. I'm sans MATLAB for a little while or I'd help throw a few compat. tests together. basically I've been throwing Nan and  at each input, then combinations of them for multi input functions, then a couple n-dimensional input forms ( nan(2,2), ones(2,0,1), etc) I think I had stumbled into their general handling scheme for the empties when I redid the statistics functions . Don't know how much of that carries through for other functions.