2D normal distribution with variable array

I am trying to make a 2D vaiable array in 'r' so that I can generate a 2D normal distribution.

I have the code for the 'r' array but I am having difficulty implementing it into the 2D normal distribution function.

Here is what my code looks like for the 'r' array (222 x 222):

N=222

for j=1:N

   for i=1:N

       r(i,j)=sqrt((i-N/2)^2 + (j-N/2)^2)

end

end

Again I'm not sure how to put this 'r' array into a 2D normal distribution function.

Any help would be appreciated