As value of a decrease , M is computed in for loop and G2 is generated having rows equal to M, than i want to copy G1 rows portion equal to size of M to G2 in each iteration of for loop from maximum row to minimum,

   G1 = [1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1;
       0     0     0     0     0     0     0     0     1     1     1     1     1     1     1     1;
       0     0     0     0     1     1     1     1     0     0     0     0     1     1     1     1;
       0     0     1     1     0     0     1     1     0     0     1     1     0     0     1     1;
       0     1     0     1     0     1     0     1     0     1     0     1     0     1     0     1;
       0     0     0     0     0     0     0     0     0     0     0     0     1     1     1     1;
       0     0     0     0     0     0     0     0     0     0     1     1     0     0     1     1;
       0     0     0     0     0     0     1     1     0     0     0     0     0     0     1     1;
       0     0     0     0     0     0     0     0     0     1     0     1     0     1     0     1;
       0     0     0     0     0     1     0     1     0     0     0     0     0     1     0     1;
       0     0     0     1     0     0     0     1     0     0     0     1     0     0     0     1];
  m=4;
  r=4;
  k=0;
  n=2^m;
  for i=1:r
      k= k+factorial(m)/(factorial(m-i)*factorial(i));

end

for a=r:-1:2
    M=factorial(m)/(factorial(m-a)*factorial(a));
    G2 = zeros(M,n);
    for o=M:1:1
       G2(o,:) = G1(k,:);
       k=k-1;
    end
end