simple question



Dear all,
I have a very simple question. If you can answer, I really appreciate. How
can I build a matrix with all its elements zero with a simple command?
In example I want to build a matrix like

A=matrix(
 [0,0,0],
 [0,0,0],
 [0,0,0]
);

but it is very hard to make it if you define all the elements and if you
have say a 100*100 matrix.
There should be a simple command but I cannot find it in the manual. Also
its elements are not forced to be zero. I want to make A a matrix with
100*100 elements in example. Then I will define myself its elements with a
for next like loop...

Best Regards
Ahmet Alper Parker