[Gretl-devel] Re. gretl too liberal with zero-length matrices

In http://lists.wfu.edu/pipermail/gretl-devel/2012-December/004176.html I wrote: <quote> 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.) </quote> Sorry: Error, Fail! This "fix" broke things that are stated to work in the manual (e.g. the ability to use a null matrix as the basis for either row or column concatenation). I think that's now put to rights in CVS. Maybe not for right now, but... I tend to think that we should not allow the construction of matrices like the one in Sven's example above -- that is, with zero rows but a positive number of columns or vice versa. You can have a proper null matrix, or you can have a matrix with rows > 0 and cols > 0, but not a chimera. As I mentioned, doing "zeros(0,9)" would (silently) produce a proper null matrix (0x0) until recently. That was not very satisfactory and for the present I've left in place the "fix" that produces a 0x9 matrix, but I think that shouldn't stand for long. Thoughts? Allin