How to bode plot exp(-0.1s) - 1?

I wanted to reproduce this example on my own, but I couldn't figure out how to bode plot exp(-0.1s) - 1. I tried:

f = tf([exp(-0.1) -1], [1]);
bode(f)

Which gave me a different bode plot from the book.

Any idea?

Answer 1

[Star Strider]

You have to set the transfer function variable to ‘continuous’ with the initial tf call, then you can use symbolic variables in the transfer function.

The Code —

s = tf('s');
f = exp(-0.1*s);
[mag,phase,wout] = bode(f-1, {1E-1 1E+3});

figure(1)
subplot(2,1,1)
loglog(squeeze(wout), squeeze(mag))
set(gca, 'YLim',[1E-3  1E1])
grid
subplot(2,1,2)
semilogx(squeeze(wout), squeeze(phase))

This plot will reproduce the solid line in FIGURE 4.1.