Negative index of a matrix

for n=1:5
for m=-n:n
a(m,n)=m*n
end
end

end

I got an equation like this but I got negative indexes , how can I solve this problem? Thanks for helping.

Answer 1

[Thorsten]

 for n = 1:5
   m = -n:n;
   for i = 1:numel(m)
     A(i, n) = m(i)*n;
   end
 end

[Burak]

Really thanks , I appreciate.