PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

58 Practical MATLAB® Applications for Engineers

1.4 Examples

Example 1.1

Create the script fi le disc_func that returns the plot of the following discrete function

(Figure 1.49):

ƒ(n) = − 5
(n + 4) +
(n) + 2
(n − 3)

MATLAB Solution

% Script file : disc _ func

n = -10:10; % vector n from -10 to +10

fn = [zeros(1,6) -5 zeros(1,3) 1 zeros(1,2) 2 zeros(1,7)];

yzero = zeros(1,21);

% plot the function f(n)

stem(n,fn) % plot the function f(n)

hold on;plot(n,yzero);

xlabel(‘time index, n’)

ylabel(‘Amplitude’)

axis([-10 10 -7 4])

title(‘f(n) = -5\delta(n+4) + \delta(n) +2\delta(n-3)’)

Example 1.2

Create the script fi le analog_func that returns the plot of the analog signal given by

ƒ(t) = u(t) + u(t − 1) + u(t − 2) − 3u(t − 3)

over the range − 1 ≤ t ≤ 5 (Figure 1.50).

f(n) = − 5 δ(n + 4) + δ(n) + 2δ(n−3)

4

3

2

1

− 1

− 2

− 3

− 4

− 5

− 6

− 10 − 8 − 6 − 4 − 2 0246810

− 7

0

time index, n

Amplitude

FIGURE 1.49

Plot of Example 1.1.