On Fri, 7 Dec 2012, Sven Schreiber wrote: Fair enough. A related point is that, up till now, "zeros(0,9)" didn't actually produce a 0 x 9 matrix, the result was 0 x 0. That's now fixed in CVS, along with the conformability question. For row concatenation, '|', the two matrices must always have the same number of columns, and for column concatenation, '~', they must always have the same number of rows. (Although I do retain a suspicion that it's not altogether meaningful to say a matrix has 9 columns when it has zero rows.) Allin