a = zeros(4);
% prepare the matrix
% 1 1 1 1
% 2 4 8 16
% 3 9 27 81
% 4 16 64 256
for i = 1:4
  for j = 1:4
    a(i, j) = i^j;
  endfor
endfor
b = inverse(a);
a * b