信号与系统，用matlab实现z变换，零极点，频率响应相位响应，群延迟

[num,den] = rcosine(1,2,'sqrt');
Gz = tf(num,den,1)

figure
pzmap(Gz)

figure
freqz(num,den)

figure
grpdelay(num,den)

结果：

Gz =
 
                                                                                                                                   
  0.002144 z^12 - 0.01061 z^11 + 0.03001 z^10 - 0.05305 z^9 - 0.07503 z^8 + 0.4092 z^7 + 0.8037 z^6 + 0.4092 z^5 - 0.07503 z^4     
                                                                                                                                   
                                                                                 - 0.05305 z^3 + 0.03001 z^2 - 0.01061 z + 0.002144
                                                                                                                                   
 
Sample time: 1 seconds
Discrete-time transfer function.