Hi, maybe this has come up before, but if so then I don't remember the answer: I just noticed that I can stick together horizontally (as in 'x ~ y') a 100x2 matrix and a 1x100 row vector. However, the result was that the first element of the row vector was repeated 100 times and formed the third column of the output. So effectively I got: x ~ (y[1] .* ones(rows(x), 1)) What was intended instead was: x ~ y' where I simply forgot the transpose. Try it for yourselves: <hansl> matrix x = ones(10,2) matrix y = seq(0,9) matrix out1 = x ~ y' # intended print out1 matrix out2 = x ~ y # what I got print out2 </hansl> I guess this comes from gretl *trying* to broadcast the vector y to match the dimensions of x, but I would not really call the result broadcasting. Or is there a rationale for this behavior? thanks, sven