%  ex_07_06_1.m :  習(xí)題 7.6

clear all;
N=31;
wr=boxcar(N); %  for boxcar window;
[WR,f]=freqz(wr,1,256,'whole',1);
WR=20*log10(abs(WR)/abs(WR(1)));
wt=triang(N); %  for triangle window
[WT,f]=freqz(wt,1,256,'whole',1);
WT=20*log10(abs(WT)/abs(WT(1)));

wh=hamming(N);%  for Hamming window;
[WH,f]=freqz(wh,1,256,'whole',1);
f1=f-0.5;plot(f1,fftshift(WH))
WH=20*log10(abs(WH)/abs(WH(1)));
t=0:N-1;f=f-0.5;
%
subplot(321);stem(t,wr,'.k');grid on;
subplot(322);plot(f,fftshift(WR));grid on;
subplot(323);stem(t,wt,'.k');grid on;
subplot(324);plot(f,fftshift(WT));grid on;
subplot(325);stem(t,wh,'.k');grid on;
subplot(326);plot(f,fftshift(WH));grid on;