>
> great ! that suits me perfectly, at least until I found a "higher level"
> way
>
It is not clear to me what you are trying to do.
Depending on what your goal is, you might want to simply assign the whole
matrix, e.g.
U: Fm$
This does not modify the elements of U; it just assigns a different value to
U. Note that after this assignment, both U and Fm hold *the same* matrix,
so if you modify one, you modify the other.
-s