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This document explains the very basic fundamentals of MATLAB software. The person will be able to write down a very long and meaningful MATLAB code specially in courses related to electrical engineering
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Prof. Mohamed Zribi
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Prof. Mohamed Zribi
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Prof. Mohamed Zribi
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What is MATLAB?
^
MATLAB is a program for doing numerical computation. It wasoriginally designed for solving linear algebra type problemsusing matrices. It’s name is derived from
rix
oratory.
^
MATLAB has since been expanded and now has built-infunctions for solving problems requiring data analysis, signalprocessing, optimization, and several other types of scientificcomputations.
It also contains functions for 2-D and 3-D
graphics and animation. Prof. Mohamed Zribi
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What is MATLAB?
^
The MATLAB environment is command oriented somewhat likeUNIX. A prompt appears on the screen and a MATLABstatement can be entered. When the
key is pressed,
the statement is executed, and another prompt appears. ^
If a statement is terminated with a semicolon (
), no results will
be displayed. Otherwise results will appear before the nextprompt. Prof. Mohamed Zribi
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What is MATLAB?
^
MATLAB is basically a
high level language
which has many
specialized toolboxes for making things easier for us ^
How high?
High Level Languages such as
C, Pascal etc.
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Why MATLAB
^
C++, Fortran, Java
Excel, MathCad, Mathematica, Labview ^
Designed for complex numerical calculations
Vast array of Toolboxes for different specialties
Excellent visualization tools
Symbolic math somewhat awkward
SIMULINK for modeling dynamic systemsProf. Mohamed Zribi
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MATLAB Toolboxes
^
Communications ^
Signal Processing ^
Image Processing ^
System Identification ^
Control System ^
Robust Control ^
Curve Fitting ^
Filter Design ^
Fixed-Point ^
Fuzzy Logic ^
Genetic Algorithm ^
Image Acquisition ^
Mapping
^
Neural Network ^
Optimization ^
Parallel Computing ^
Partial Differential Equation ^
Spline ^
Statistics ^
Wavelet
Filter Design
^
Fuzzy Logic ^
μ-Analysis and Synthesis ^
LMI Control ^
Model Predictive Control
MATLAB Toolboxes include: Prof. Mohamed Zribi
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Prof. Mohamed Zribi
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MATLAB Toolboxes
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Starting MATLAB
^
^
from
Start Menu
Select
Programs
Select
MATLAB
^
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MATLAB
Screen
^
Command Window ^
type commands
^
Current Directory ^
View folders and m-files
^
Workspace ^
View program variables ^
Double click on a variableto see it in the Array Editor
^
Command History ^
view past commands ^
save a whole sessionusing diary
MATLAB PromptTells that MATLABis ready for yourcommand
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Prof. Mohamed Zribi
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Desktop Tools
^
type commands ^
view program variables
clear
to clear
double click on a variable to see it in the Array Editor ^
view past commands
save a whole session using
diary
^
access tools, demos and documentation
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MATLAB shortcuts
Help
SIMULINK
Open files
Newfile Prof. Mohamed Zribi
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MATLAB Operators
(cont.)
Operator
Description
+^
Addition
-^
Subtraction
.*^
Multiplication (element wise)
./^
Right division (element wise)
.^
Left division (element wise)
=^
Assignment operator,e.g. a = b,(assign b to a)
:^
Colon operator (Specify Range )
.^^
Power (element wise)
'^
Transpose
*^
Matrix multiplication
/^
Matrix right division
^
Matrix left division
;^
Row separator in a Matrix
^^
Matrix power
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MATLAB as a CALCULATOR Command window
39*4.4+5ans =
Command window
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MATLAB as a CALCULATOR
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MATLAB as a CALCULATOR >> 8/10ans =
>> 5ansans =*
>> r=8/10r =
>> rr =
>> s=20rs =*
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Order of Precedence( VERY Important to understand!)
•Higher-precedence operations are executed before lower-precedence operations•If two operations have the same precedence, then the expressionis executed from left to right.
First
Parentheses (innermost pair first)
Second
Exponentiation
Third
Multiplication and division
Fourth
Addition and subtraction
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Order of Precedence - Examples
( a=1, b=2, c=4, d=5 )
a + b/c + d
evaluates to
(a + b)/c + d
(a + b)/(c+d)
a + b/(c+d)
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MATLAB as a CALCULATOR
8 / 2
is executed first
>> 7 + 8 / 2ans =
11
Type and press
Enter
Computer response
(7 + 8)
is executed first
>> (7 + 8) / 2ans =
7.
Type and press
Enter
Computer response
27 ^ 1
and
32 ^ 0.
are executed first
/^ is executed next +^
is executed last
>> 27 ^ 1 / 3 + 32 ^ 0.2ans =
**11
27 ^ (1 / 3) + 32 ^ 0.2ans =**
5
(1 / 3)
is executed first
^^
is executed next +^
is executed last
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MATLAB as a CALCULATOR >> 8 + 35ans =*
>> 8 + (35)ans =*
>>(8 + 3)5ans =*
>>4^212 8/42ans =*
>>4^212 8/(42)ans =*
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Entering Commands and Expressions ^
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Commands for Managing the Work Session clc
clears the command window, but doesn’t eliminate variables
clear
removes all variables from memory
clear var1 var2 var3…
clears specified variables from memory
clear all
removes all variables and functions from memory
who
lists the variables in memory
whos
lists the variables in memory and provides additional information
what
lists the m-files in the current directory
quit
stops MATLAB.
…
“ellipses” – used to continue your expression onto the next line
dir
Lists the contents of the current working directory
save filename var1 var2….save filename var1… -ascii
Saves variables into the file named filename in MATLAB formatSaves variables into an ASCII formatted file.
diary filenamediary on/off
Starts a diary session that saves Command Window information into a file
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Commands for Managing the Work Session
(cont.)
ls^
Same as dir
type test
Display test.m in command window
delete test
Delete test.m
cd a:
Change directory to a:
chdir a:
Same as cd
pwd
Show current directory
which test
Display current directory path to test.m
more on/off
Enables/disables paged output
ctrl+c
Aborts operation
why
In case you ever needed a reason
which functionPath , addpathpathtool tic
,^ toc
bracketing code to measure execution time
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pi:
value up to 15 significant digits
i, j: sqrt(-1)
-^
Inf: infinity (such as division by 0)
-^
NaN: Not-a-Number (division of zero by zero)
-^
clock: current date and time in the form of a 6-element rowvector containing the year, month, day, hour, minute, andsecond
-^
date: current date as a string such as
19-Dec-
eps: epsilon is the smallest difference between two numbers
-^
MATLAB Special Variables( do not use as variable names! ) ans: stores the result of an expression
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beep :
make sound
realmin, realmax :
smallest & largest positive real numbers
vitmax :
largest positive integer
nargin, nargout :
number of in (or) out variables in a function
varargin :
variable number of function in arg’s
varaout :
variable number of function out arg’s
MATLAB Special Variable( do not use as variable names! )
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Reserved Words
forendifwhilefunctionreturnelsifcaseotherwise
switchcontinueelsetrycatchglobalpersistentbreak
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MATLAB
Variables
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MATLAB Variable Names
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Defining Variables
^
^
^
int a;double b;float c;
Example:>>x=5;>>x1=2;
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Variables - Example
^
^
^
Matlabprompt
assignoperator
suppresscommandoutput
commentoperator
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Variable Name Examples
log(5)ans =
log = 4
% Very bad practice
log =
log(5)??? Index exceeds matrix
dimensions.
clear log>> log(5)ans =
Abc=123Abc =
ABc??? Undefined function orvariable 'ABc'.
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Variables - Example
View variable
contents by simply typing the variable name at
the command prompt
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Display contents of workspace>>
whos Name
Size
Bytes Class
a^
1x
8 double array
b^
1x
8 double array
c^
1x
8 double array
Grand total is 3 elements using 24 bytes>> Delete variable(s) from workspace >> clear a b;
% delete a and b from workspace
whos>> clear all;
% delete all variables from workspace
whos >>
exist
(‘var’)
%^
Determines if a file or variable exists having the % name ‘
var
’.
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Constants and Functions - Example
pians =
epsans = 2.2204e-016>> sin(pi/2)ans =
1
log(1000)ans =
log10(1000)ans =
3
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Constants - Example
bitmaxans = 9.0072e+015>> epsans = 2.2204e-016>> realminans = 2.2251e-308>> realmaxans = 1.7977e+308>> ansans = 1.7977e+308>> ians =
0 + 1.0000i
infans =
Inf
NaNans =
NaN
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Arrays
^
^
^
^
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Arrays
^
Scalar:
1 by 1 Array
^
Vector:
Array with one dimension
^
Matrix:
Array with more than one dimension
^
Size
of an array is specified by the number of rows and the number of columns, with the number of rows mentioned first (For example: n x m array).Total number of elements in an array is the product of the number of rows andthe number of columns. Prof. Mohamed Zribi
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^
Arrays are constructed using brackets and semicolons. All of the elements ofan array are listed in row order. ^
The values in each row are listed from left to right and they are separated byblank spaces or commas. ^
The rows are separated by semicolons or new lines. ^
The number of elements in every row of an array must be the same. ^
The expressions used to initialize arrays can include algebraic operations andall or portions of previously defined arrays.
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Vectors and Matrices
^
^
^
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Vectors and Matrices - Example
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Vectors and Matrices - Example
A matrix with only one column is called a column vector. A
column vector can be created in MATLAB as follows (notethe semicolons): » col_vec = [13 ; 45 ; -2]col_vec =
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Vectors and Matrices - Example
square brackets to define matrices
semicolon for next row in matrix
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Vectors and Matrices - Example
A matrix can be created in MATLAB as follows (note the
commas AND semicolons): » matrix1 = [1 , 2 , 3 ; 4 , 5 ,6 ; 7 , 8 , 9]matrix1 =
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Vectors and Matrices - Example
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Vectors and Matrices - Example
Notice that the array subscripts in Matlab start from 1 and not0 as is the case in C.Illustration:>> A = [1 2 3 4];>> A(0)
% This command will result in syntax error
The first index is 1 and not 0.>> A(1)ans = 1 Prof. Mohamed Zribi
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The : operator
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The : operator - Example
x = 1 : 7
% same as
x = [ 1 : 7 ]
x = [ 1 2 3 4 5 6 7]
y = 0 : 3 : 12
y = [ 0 3 6 9 12 ]
y = 0 : 3 : 11
y = [ 0 3 6 9 ]
z = 15 : -4 : 3
z = [ 15 11 7 3 ]
w = 0 : 0.01 : 2
w = [ 0 0.01 0.02 ... 1.99 2.00 ]
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Vectors and Matrices - Example
^
x = [1,2,3]
% vector-row,
^
y=[1;2;3]
% vector-column,
^
x=0:0.1:0.
% vector x=[0,0.1,0.2,0.3....0.8],
^
A = [1,3,5;5,6,7;8,9,10]
% matrix,
^
A(1,2)
% element of matrix, 1. row, 2. column,
^
A(:,2)
% second column of matrix,
^
A(1,:)
% first row of matrix ,
^
C=[A;[10,20,30]]
% matrix with additional row,
^
A(:,2)=[]
% deleting of second column,
^
B=A(2:3,1:2)
% part of matrix,
^
x’
% transpose.
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Manipulating Matrices - Example
A =
3
2
1
5
1
0
2
1
7
indices of matrix element(s)
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Manipulating Matrices - Example
A=
[
1
2
3
;
4
5
6
;^
7
8
9];
x
=
A
(
1,
3
)
%^
A(
x^
= 3
y
=
A
(
2
,
:
)
%^
selects
the
2
nd
row
y^
= 4
5
6
z
=
A
(
1:
,
1:
)
%^
selects
sub-matrix
z^
= 1
2
3
4
5
6
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Assigning a scalar to a subarray: A scalar value on the right-hand side of an assignment statement is copied into everyelement specified on the left-hand side.
arr4 = [1 2 3 4; 5 6 7 8; 9 10 11 12];>> arr4(1:2, 1:2) = 1arr4 =
Manipulating Matrices - Example
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