%  ex_07_05_1.m :  習題 7.5

clear all;
order = 54;
f = [0, 0.05, 0.1, 0.15, 0.18, 0.25, 0.3, 0.36, 0.41, 0.5] * 2;
a = [0, 0, 1, 1, 0, 0, 1, 1, 0, 0];
wtx = [1, 10, 1, 10, 1];
b = firpm(order, f, a, wtx);
[h, w] = freqz(b, 1, 512);
subplot(221);plot(f,a,w/pi,abs(h));grid;
subplot(222);plot(w/pi,20*log10(abs(h)));grid;

wtx = [10, 1, 10, 1, 10];
b = firpm(order, f, a, wtx);
[h, w] = freqz(b, 1, 512);
subplot(223);plot(f,a,w/pi,abs(h));grid;
subplot(224);plot(w/pi,20*log10(abs(h)));grid;

figure
wtx = [1, 1, 1, 1, 1];
b = firpm(order, f, a, wtx);
[h, w] = freqz(b, 1, 512);
subplot(221);plot(f,a,w/pi,abs(h));grid;
subplot(222);plot(w/pi,20*log10(abs(h)));grid;
subplot(223);stem(b,'k.');
pha=angle(h);pha=unwrap(pha);
subplot(224);plot(w/pi,pha);
%legend('Ideal','Parks-McLallan Design');
%figure;
%freqz(b, 1, 512);