N=128
downTo=8;
DFTM=zeros(N,N);
for n=1:N
  for k=1:N
     DFTM(n,k)=exp(-i*2*pi*(k-1)*(n-1)/N);
  end
end
time=1:N

mystep=N/downTo
for s=1:downTo
    subplot(downTo,1,s);
    plot3(time,real(DFTM(1+(s-1)*mystep,:)),imag(DFTM(1+(s-1)*mystep,:)));
    grid off;
    ylim([-1,1]);
    zlim([-1,1]);
    view ([3,30]);
end