%  ex_07_08_1.m :  習(xí)題 7.8

clear all;
close all;

clc;
m_b=0.5;
m_a=0;
N=20;
b=[m_b 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 m_b];
a=[1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 m_a];
subplot(221)
zplane(b,a);
%
[H,f]=freqz(b,a,1024,1);
Hr=abs(H);
f=f;
subplot(222)
plot(f,Hr);