How to vectorize double sum

Please how can i vectorize this double sum

N=4
x=randn(3,N);
for i=1:N-1
    for j=2:N
        if j>i
            a=x(:,i)-x(:,j)
        end
    end
end

Answer 1

[Stephen23]

>> N = 4;
>> x = randi(9,3,N)
x =
   5   4   8   9
   2   9   9   8
   1   1   4   1
>> F = @(c)bsxfun(@minus,x(:,c),x(:,c+1:N));
>> M = cell2mat(arrayfun(F,1:N-1,'uni',0))
M =
   1  -3  -4  -4  -5  -1
  -7  -7  -6   0   1   1
   0  -3   0  -3   0   3

[Esegboria Osarhemen]

Thanks