N=100;
n=0:N-1;
f=n/N;
xn=cos(0.48*pi*n)+cos(0.52*pi*n);
xk=fft(xn);
Axk=abs(xk);
figure(1);
subplot(2,1,1);
stem(n,xn);
xlabel('n');
ylabel('x(n)');
title('the Original Signal');
subplot(2,1,2);
stem(f,Axk);
xlabel('k');
ylabel('X(k)');
title('the DFT of the Signal');