PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

Fourier and Laplace 377

figure(1); % Figure 4.28, part(a)

subplot(2,2,1);

plot(t,Harmonic _ 1);

title(‘fundamental freq. wo=pi’);

ylabel(‘Amplitude’);

subplot(2,2,2);

plot(t,Harmonic _ 3);

title(‘3rd. harmonic, freq.w=3*wo’);

ylabel(‘Amplitude’);

subplot(2,2,3);

plot(t,Harmonic _ 5);

title(‘5th. harmonic, freq.w=5*wo’);

ylabel(‘Amplitude’);

xlabel(‘ time (in sec)’);

subplot(2,2,4);

plot(t,Harmonic _ 7);

title(‘7th. harmonic, freq.w=7*wo’);

ylabel(‘Amplitude’); axis([0 4 −0.15 0.15])

xlabel(' time (in sec)');

figure(2); % Figure 4.29, part (b)

plot(t,Harmonic _ 1,t,Harmonic _ 3,t,Harmonic _ 5,t,Harmonic _ 7);

title('Harmonic components of the square wave');

ylabel('Amplitude');

xlabel('time (sec) ');

figure(3); % Figure 4.30, part(c)

subplot(2,2,1)

plot(t,Harmonic _ 1);

title('fundamental frequency (square)');

ylabel('Amplitude');

subplot(2,2,2);

Har _ 13 = Harmonic _ 1+ Harmonic _ 3;

plot(t,Har _ 13);

title('fund.+ 3rd. harmonic ');

ylabel('Amplitude');

subplot(2,2,3);

Har _ 135 = Harmonic _ 1+ Harmonic _ 3+ Harmonic _ 5;

plot(t,Har _ 135);

title('fund.+3rd.+ 5th harmonic ');

ylabel('Amplitude');

xlabel('time (in sec)');

subplot(2,2,4);

Har _ 1357 = Harmonic _ 1+ Harmonic _ 3+Harmonic _ 5+Harmonic _ 7;

plot(t,Har _ 1357);

title('fund.+ 3rd.+ 5th.+ 7th. harmonic ');

ylabel('Amplitude');

xlabel('time (in sec)');

figure(4); % Figure 4.31, part (d)

plot(t,Harmonic _ 1,t,Har _ 135,t,Har _ 1357);

title('Plots of square wave approximations using harmonics ');

xlabel('time (in sec)');

ylabel('Amplitude');