PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

368 Practical MATLAB® Applications for Engineers

plot (t,f)

title (‘ plot of [ ILT of F(s)] vs. t (numerical solution)’)

ylabel (‘Amplitude’); xlabel (‘time t’);

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

syms s t;

disp(‘F(s) is given by:’)

F = (3*s+25)/(s^2+3*s+2);

pretty(F)

disp(‘The ILT of F(s)is given by:’)

FILT = ilaplace(F);

pretty (FILT)

subplot (3,1,2)

ezplot (FILT,[0 10])

title (‘ plot of f(t) vs. t (symbolic solution) ‘)

xlabel (‘time t’); ylabel(‘Amplitude’)

subplot(3,1,3)

ezplot (F,[0 10])

title (‘ plot of F(s) vs.s (symbolic) ‘)

xlabel (‘s (frequency)’)

ylabel(‘Amplitude’)

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

The script fi le F_ f is executed and the results are indicated as follows.

>> F _ f

plot of [ILT of F(s)] versus t (numerical solution)

Time t

Time t

plot of f(t) versus t (symbolic solution)

plot of F(s) versus s (symbolic)

s (frequency)

Amplitude

Amplitude

Amplitude

10

0

01234 567891 0

01234 678910

0

0

2

4

6

0

2

4

6

12345678910

5

5

FIGURE 4.19
Plots of R.4.121.