clear;
j = sqrt(-1);
H=zeros(1,12);
H(1) = 0;
H(2) = 0;
H(3) = 0.7*exp(-j*pi*2*11/12);
H(4) = exp(-j*pi*3*11/12);
H(5) = 0.7*exp(-j*pi*4*11/12);

H(9) = conj(H(5));
H(10) = conj(H(4));
H(11) = conj(H(3));


h = real(ifft(H));

[Hf,Wf] = freqz(h,1,500); 

Ff = Wf/(2*pi);
F=[0:6]/12;
plot(Ff,abs(Hf),F,abs(H(1:7)),'o');zoom;grid;
hold;

h = h.*hamming(12)';
Hf1 = freqz(h,1,500); 
plot(Ff,abs(Hf1),'r');

% Usando la funcion fir2

B = fir2(11,[0 1 2 3 4 5 6]*2/12,[0 0 0.7 1 0.7 0 0],boxcar(12));
Hf2 = freqz(B,1,500);

plot(Ff,abs(Hf2),'m');