PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

Time Domain Representation of Continuous and Discrete Signals 71

figure(1)

subplot(2,2,1);

Y1 = filter(P, Q, I); n=0:29; yzero=zeros(1,30);

stem(n, Y1);hold on; plot (n,yzero);

title(‘impulse response using a sequence’);

ylabel (‘Amplitude imp. resp.’);

subplot (2,2,2);

Y2 = filter(P,Q,S);

stem (n, Y2);hold on; plot(n,yzero);

title(‘step response using a sequence’);

ylabel(‘Amplitude step resp.’);

subplot(2,2,3);

Y3 = dimpulse(P, Q, n);

stem(n, Y3);hold on; plot(n,yzero);

title(‘impulse response using dimpulse’);

ylabel (‘Amplitude imp.resp.’);

xlabel (‘time index n’);

subplot (2,2,4);

Y4 = dstep(P, Q, n);

stem(n, Y4); hold on; plot(n,yzero);

title(‘step response using dstep’);

ylabel(‘Amplitude step resp.’);

xlabel(‘time index n’)

The script fi le disc_tranf_func is executed and the results are shown in Figure 1.60.

Note that the results of part a fully agree with the results obtained in part b.

FIGURE 1.60

Plots of system responses of Example 1.11.

impulse response using a sequence

2

1

− 1

− 2

0

(^0102030)
Amplitude imp. resp.
impulse response using dimpulse
2
0
0
− 1
− 2
1
Amplitude imp. resp.
10 20 30
time index n
0102030
time index n
step response using a sequence
step response using dstep
1.5
1
0.5
−0.5
1.5
−0.5
0.5
0
1
0
0 10 20 30
Amplitude step resp.
Amplitude step resp.