filter1.m

the programs are an introduction to DSP ,the programs illustrate the frequency response ,impulse res

function filter_demo1

z = input ('zeros = ');
% z: Zeros in the z-plane
p = input ('poles =');
% p: poles in the z-plane
k = input ('filter gain =');

z=z.'; p=p.';
zplane (z,p)

pause

[num,den]=zp2tf(z,p,k);

n=0:100;
imp=zeros(101,1);
imp(1)=1; x=imp;

h=filter(num,den,x);
subplot, stem(n,h)
title('Impulse Response')
xlabel('index (n)'),ylabel('h(n)')

hold off
pause
figure
[H,W]=freqz(num,den,512);
subplot(211), plot(W/2/pi,abs(H))
xlabel('f (normalized Hz)'),ylabel('Magnitude Response')
subplot(212), plot(W,angle(H))
xlabel('w (rad)'),ylabel('Phase Response')