This document provides an introduction to using MATLAB for numerical computations and graphical output. It describes how to launch MATLAB, perform basic arithmetic operations and matrix calculations, use loops to iterate calculations, and generate different types of plots and graphs including sine waves, bar graphs, and subplots. The exercises walk through examples of these MATLAB functions and commands to familiarize users with its interface and capabilities.

1. POLYTECHNIC UNGKU OMAR
ELECTRICAL ENGINEERING DEPARTMENT
Course : E5124 DATA COMMUNICATION (Lab work)
Experiment : Matlab 1 – Get Familiarize (Matrices and Plot)
The objective of this session is to learn:
- How to launch the matlab software
- Few simple calculations and formulation
- Plot command and graphical output
Introduction
Matlab is a tool for doing numerical computations with matrices and vectors. It can also display information
graphically. The best way to learn what Matlab can do is to work through some examples at the computer. After
reading and familiarize with this exercise you will be able to solve construct own work.
Starting MATLAB
Launch MATLAB by double-clicking on the MATLAB icon on your Windows desktop. When you start MATLAB, a
special window called the MATLAB desktop appears. The desktop is a window that contains other windows. The
major tools within or accessible from the desktop are (refer Fig 1):
- The Command Window
- The Command History
- The Workspace
- The Current Directory
- The Help Browser
- The Start button
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2. Fig 1 : The graphical interface to the Matlab workspace
Table below shows arithmetic operators for calculation and equation in Matlab application.
As an example of a simple interactive calculation, just type the expression you want to evaluate. Let's start at the
very beginning. For example, let's suppose you want to calculate the expression, 1 + 2 x 3. You type it at the prompt
command (>>) as follows,
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3. >> 1+2*3
ans =
7
You will have noticed that if you do not specify an output variable, MATLAB uses a default variable ans, short for
answer, to store the results of the current calculation. Note that the variable ans is created (or overwritten, if it is
already existed). To avoid this, you may assign a value to a variable or output argument name. For example,
>> x = 1+2*3
x=
7
will result in x being given the value 1 + 2 x 3 = 7. This variable name can always be used to refer to the results of the
previous computations. Therefore, computing 4x will result in
>> 4*x
ans =
28.0000
Exercise
1. Matrix
1.1 Insert the following expression and observe the result.
>>aa=[l 3 4; 5 7 8; 2 3 5]
Observation
>> y=[10; 9; 8]
Observation
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4. 1.2 Insert both expressions.
>>aa=[l 3 4; 5 7 8; 2 3 5];
>> y=[10; 9; 8];
Now obtain result for following expression
>>aay
Observation
>>inv(aa)*y
Observation
>> [inv(aa)*y aay]
Observation
Explain your observation for expression [inv(aa)*y aay]
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2. Matrix Loop
2.1 Insert following expression and obtain result
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5. >> a = [ 0.8 0.1; 0.2 0.9 ]
Observation
>> x = [ 1; 0 ]
Observation
2.2 Type below expression and state your observation
>> a = [ 0.8 0.1; 0.2 0.9 ];
>> x = [ 1; 0 ];
>> for i = 1:20, x = a*x, end
Observation
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6. 3. Plot
MATLAB has an excellent set of graphic tools. Plotting a given data set or the results of computation is
possible with very few commands. You are highly encouraged to plot mathematical functions and results of
analysis as often as possible. Trying to understand mathematical equations with graphics is an enjoyable and
very e±cient way of learning mathematics. Being able to plot mathematical functions and data freely is the
most important step, and this section is written to assist you to do just that.
3.1 Let say, your given few samples of variable which need to find out their performance rate. Now, insert following
expression:-
>> a=[1 2 3 4 6 4 3 4 5]
Observation
>> b=a+2
Observation
3.2 Use plot command to plot your result.
>> plot(b)
Observation
>> grid on
Observation
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7. 3.3 Use label and title command to provide information at graph. Type this command step by step in order to
observe result. Before you type command, display your Matlab window panel and graph window side by
side in order to get better view.
>> xlabel('Sequence of b')
>> ylabel('b value')
>> title(‘Graphical output for b sequence of number’)
Observation
3.4 Bar command used to plot bar graph which able to show us the statistical result.
>> bar(b)
>> xlabel('Number of sample')
>> ylabel('Weight of random samples in kg')
Observation
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8. >> plot(b,'*')
>> axis([0 12 0 10])
Observation
What did you see from both graphs? Explain.
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3.5 To make a graph of y = sin(t) on the interval t = 0 to t = 10, do the following steps:
>> t = 0:.3:10;
>> y = sin(t);
>> plot(t,y)
>> title('Sine wave ')
>> xlabel(‘Time, t')
>> ylabel('Amplitude')
Observation
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9. 3.6 Plotting multiple wave or result in single graph. Execute following command and make your observation.
Insert title and label by yourself.
>> t=0:0.1:30;
>> y1=sin(t);
>> y2=cos(t);
>> plot(t,y1,'--',t,y2,'-r')
Observation
>> t=0:0.1:30;
>> y1=sin(t).*t;
>> y2=cos(t).*t;
>> plot(t,y1,'--',t,y2,'-r')
Observation
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10. 3.7 Subplot
The subplot is used to put multiple plots on the same MATLAB figure window.
subplot(pqr) - p & q represent matrixes, r locating position for plotted graph
a) Write the following expression and obtain the result.
>> x = 0 : 0.1 : 3 *pi;
>> y = sin(x);
>> z = cos(x);
>> subplot(222)
>> plot(x,y)
>> title('Sine wave y')
>> xlabel('time, x')
>> ylabel('Amplitude, y')
>> subplot(223)
>> title('x and z')
>> subplot(224)
>> plot(x,y,'-',x,z,' -- ')
>> title('x and [y z]')
b) Once complete your subplot, insert label and title for each graph individually. Use example as given in
above command.
Observation
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11. c) Discrete sample graphical output.
Type following command and make observation. State the differences between both results.
>> p=0:0.05:5;
>> q=sin(p.^2);
>> plot(p,q);
Observation
>> p=0:0.05:5;
>> q=sin(p.^2);
>> stem(p,q);
Observation
Reflection
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