% spatna x(n) z X(k)
function x = DFT_spatna(X)
  N = length(X);
  x = zeros(1,N);
  for n = 0:(N - 1)
    xn = 0;
    for k = 0:(N - 1)
      xn = xn + ( X(k + 1) .* exp(1j * 2 * pi * n * k / N) );
    end
    x(n + 1) =  xn;
  end
end