PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

Time Domain Representation of Continuous and Discrete Signals 43

The script fi le disc_ step is executed and the results are given as follows and in

Figure 1.38.

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The discrete step sequence u(n) for the first 10 samples is:

^^^^^^^^^^^^^^^^^^^^

n u(n)

^^^^^^^^^^^^^^^^^^^^

0 2.2400

1.0000 3.6200

2.0000 3.6568

3.0000 2.7000

4.0000 3.1534

5.0000 3.5773

6.0000 3.0570

7.0000 3.0289

8.0000 3.3968

9.0000 3.2320

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R.1.125 The MATLAB function [y, n] = fi lter(b, a, x) defi ned in Chapter 7 of the book titled

Practical MATLAB® Basics for Engineers returns the output sequence y, when the

relation input (x) output (y) is given by the following system difference equation:

ayn kk bxn l

k

N

l

l

N

==

∑∑

0

1

0

2

()
 ()

R.1.126 A discrete sequence may consist of either a fi nite or infi nite number of samples.

A fi nite length sequence is characterized by a fi nite number of nonzero sam-

ples. An infi nite length sequence extends infi nitely to the right or the left of

the n-axis (discrete time). In either case, the infi nite or fi nite sequences can be

represented by a sum of weighted time-shifted impulse samples.

Discrete step response u(n) versus n

4

3.5

2.5

2

1.5

0.5

0

0 1 2 3 4 5 6 7 8 9

1

3

time index n

Amplitude [u(n)]

FIGURE 1.38

Discrete step response of R.1.124.