PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

612 Practical MATLAB® Applications for Engineers

ylabel(‘Magnitude’);

title(‘Magnitude of H(w) vs. w [using lp2lp]’);

subplot(1,2,2)

plot(w,phase3*180/pi)

xlabel(‘frequency in rad/sec’);

ylabel(‘Angle in degrees’);

title(‘Phase of H(w) vs. w [using lp2lp]’)

disp(‘**************************************************’)

disp(‘Solution to part (e) ‘)

disp(‘Coefficients of the numerator of the trans. function [wc=2]’)

disp(P)

disp(‘Coefficients of the denominator of the trans. function [wc=2]’)

disp(Q)

tf(P,Q)

disp(‘**************************************************’)

%part(f),solution using Butter/norm.LPF

[z,p,k] = buttap(2);

[Pn,Qn] = zp2tf(z,p,k);

disp(‘**************************************************’)

disp(‘Solution to part (f) ‘)

disp(‘Coefficients of the numerator of the trans. function

[butter/LPF/wc=1]’)

disp(Pn)

disp(‘Coefficients of the denominator of the trans. function

[butter/LPF/wc=1]’)

disp(Qn)

tf(Pn,Qn)

disp(‘**************************************************’)

figure(4)

w=0:.1:3;

Hbut=freqs(Pn,Qn,w);

mag4 = abs(Hbut);

phase4 = angle(Hbut);

subplot(1,2,1)

plot(w,mag4)

xlabel(‘frequency in rad/sec.’);

ylabel(‘Magnitude’);

title(‘Magnitude of H(w) vs. w [Butter/wc=1]’);

subplot(1,2,2)

plot(w,phase4*180/pi)

xlabel(‘frequency in rad/sec’);

ylabel(‘Angle in degrees’);

title(‘Phase of H(w) vs. w [Butter/wc=1]’)

% part(g),transforming the butter/LPF using lp2lp

% with cut off frequency,wc=2 rad/sec

[Pl,Ql] = lp2lp(Pn,Qn,2);

disp(‘***************************************************’)

disp(‘Solution to part (g) ‘)

disp(‘Coefficients of the numerator of the transf. function

[butter/wc=2rad/sec]’)

disp(Pl)