What's wrong with the first method you propose?
rowVect = [x y y y y y];
If you want to generalize it (maybe you don't know the number of y's you need ahead of time)
n = number of y's you want
rowVect = [x,repmat(y,1,n)];
That being said, your two-liner above is a pretty good way of doing it. Is there some particular reason you don't like it?
