wp=0.2*pi;ws=0.3*pi;
tr_width=ws-wp;
M=ceil(6.6*pi/tr_width)+1;
n=[0:1:M-1];
wc=(ws+wp)/2;
hd=ideal_lp(wc,M);
w_ham=(hamming(M))';
h=hd.*w_ham;
[db,mag,pha,grd,w]=freqz_m(h,[1]);
delta_w=2*pi/1000;
Rp=-(min(db(1:1:wp/delta_w+1)))        
As=-round(max(db(ws/delta_w+1:1:501)))
figure(1);
subplot(2,1,1);stem(n,hd);title('理想脈沖響應');
axis([0 M-1 -0.1 0.3]);xlabel('n');ylabel('hd(n)');
subplot(2,1,2);stem(n,w_ham);title('哈明窗');
axis([0 M-1 0 1.1]);xlabel('n');ylabel('w(n)');
figure(2);
subplot(2,1,1);stem(n,h);title('實際脈沖響應');
axis([0 M-1 -0.1 0.3]);xlabel('n');ylabel('h(n)');
subplot(2,1,2);plot(w/pi,db);title('幅度響應');grid;
axis([0 1 -100 10]);xlabel('頻率');ylabel('分貝數');