% lab 6 Matlab script
% 11.10.2000

% first z-transform example: first-difference filter

b1 = [1 -1];
figure(1);
zplane(b1); % z-domain
pause

figure(2);
freqz(b1);  % frequency domain
pause

% second example: DSP First 7.6.2, ex. 7.9, pp. 222-223

b2 = [1 -2 2 -1];
figure(3);
zplane(b2); 
pause

figure(4);
freqz(b2);
pause

% third example: well-designed FIR

b3 = fir1(75, 0.2);
figure(5);
freqz(b3);  % frequency domain first this time
pause

figure(6);
zplane(b3); % then z-domain
pause

% fourth example: DC-blocking filter
b4 = [1 -1]; % first-difference FIR coeffs
a4 = [1 -0.99]; % plus additional IIR coeffs

figure(7);
zplane(b4,a4); % z-domain
pause

figure(8);
freqz(b4,a4);  % frequency domain