Introduction to

Matlab By

Abd El Kareem Ahmed

Contents

MATLAB Environment Command window, Workspace, Path window, Editor window,and

Figure window) Basic Functions: clc, clear, save, load, who, whos … Variables in MATLAB

Arrays Control flow (for – end, while – end, if – else – elseif – end, switch M-files Plotting Introduction to GUI Introduction to Image processing Toolbox

MATLAB Environment Command window

Use Menus as an alternative to typing some commands

Use of Toolbar for easy access to popular operations

Status bar

Command window

Status of Caps, Num, and Scroll locks

New M-file

Open file

Undo

New Simulink Model

Help

Cut

PasteCopy Workspace Browser

Path Browser

MATLAB Environment Workspace

Open the selected matrix

Delete the selected matrix from the workspace

Displays the total number of elements in the workspace and total size of them.

Close the workspace browser

size of the matrix Number of bytes in the matrix

Name of the matrix Type of the matrix

MATLAB Environment Workspace

Name of the matrix

Current dimension of the matrix: User can change the dimensions of the matrix by simply type the dimensions he/she want

Current Cell

Current values: User can change the values o the matrix’s element by editing in the cell.

MATLAB Environment Path browser

The current Directory

The directories in the path

The Files in the selected path.

Add a new path

Remove the selected path

MATLAB Environment Editor window

Current line number

Automatic Indenting

Aut

omat

ic C

olor

Hig

hlig

htin

g to

Dis

ting

uish

Dif

fere

nt E

lem

ents

The toolbar

Names of the opened files in the editor

New file

Save file

Copy

PrintSet/Clear break point

Step in

Continue List if functions in call stack

Open file

Cut

Paste

Help

Clear all break points

Single stepQuit debugging

MATLAB Environment Figure window

New figure

Open an exciting figure

Save the current figurePrint Zoom the plot

Rotate the plot

Start / End the plot editor mode

Draw an arrow in the plot

Type a text in the plotDraw a line in the plot

Basic Functions

Function name Function mean

clc Clear the command window

clear Clear workspace

who Show workspace

whos Show workspace in details

help Show information about any function

lookfor Search for a word in MATLAB files

save Saving workspace

load Loading saved workspace

Variables

MATLAB variables are arrays Variable must be one word

myvariable accepted my variable not accepted

Variable length is up to 31 character Variables must begin by a character MATLAB variables are case sensitive There are preserved variable names:

Variables

ans Default function output

pi Pi = 3.14

eps Very small value

inf Very large value = ∞ as the result of (1/0)

NaN When the result = 0/0

realmin Minimum real number = 10-308× 2.2251

realmax Maximum real number = 10308× 1.7977

nargin The number of input parameters

nargout The number of output parameters

Arrays : review Vector Array : (1 × n), (m ×1)

Matrix : (m × n)

Identity array

5 4 0 7

057

1 4 4 5

12 8 9 15

1 0 00 1 00 0 1

1 53 40 0

(2×4) -> (3×2) ->

(1×4) -> (3×1) ->

Arrays : review

Assume You have A = B=

A+B= A’ =

2A = =

1 3 0 2

5 4 0 7

0 1 4 3

7 4 9 8

1 4 4 5

12 8 9 15

2 6 0 4

10 8 0 14

1 53 40 02 7

a bc de f

xy

ax+bycx+dyex+fy

(m×k)(k×n)=(m×n)

Arrays : Marlab vision

m=4 m=[4]

a=3*6 m=[18]

a=[1,4,6,8,9] a=[1 4 6 8 9]

M=[2 3 5 9 1 ; 0 3 6 4 5 ; 1 10 8 6 4] M(1) 2M(6) 10M(3, 4) 6M(3, :) 1 10 8 6 4M(:, 2) 3

3

10M(1, 2:4) 3 5 9M(2, 1:2:5) 0 6 5

M= 2 3 5 9 10 3 6 4 5

1 10 8 6 4

Standard arrays

zeros zeros(3)= zeros(2,3)=

ones ones(3)= ones(2,3)=

eye eye(3)= eye(2,3)=

magic magic(3) =

rand rand(3,4) =

linspace linspace (0,4,5)= [0 1 2 3 4] linspace (1,2,3)= [1 1.5 2]

logspacelogspace (0,4,5)= [1 10 100 1000 10000]logspace (1,2,3)= [10 31.6228 100]

0 0 00 0 00 0 0

0 0 00 0 0

1 1 11 1 11 1 1

1 1 11 1 1

1 0 00 1 00 0 1

1 0 00 1 0

8 1 63 5 74 9 2

0.1389 0.6038 0.0153 0.9318

0.2028 0.2722 0.7468 0.4660 0.1987 0.1988 0.4451 0.4186

Array functions

size size(N)=[3 3] sum sum(N) = [14 9 16]

length length(N)=[3] max max(N) = [9 7 8]

det det(N)=-119 min min(N) = [1 0 3]

diag diag(N)= flipudflipud(N)=

inv fliplr fliplr(N)=

transpose (´ ) transpose(N)= rot90 rot90(N)=

find find (N ==7 ) = 5 find (N == 10 ) = []

N=1 0 34 7 59 2 8

178

9 2 84 7 51 0 3

3 0 15 7 48 2 9

3 5 80 7 21 4 9

-0.3866 -0.0504 0.1765 -0.1092 0.1597 -0.0588 0.4622 0.0168 -0.0588

1 4 90 7 23 5 8

Relational and Logical Operators

Relational Operators

Operator name Symbol Comment

eq = = equal

ne ~= not equal

lt < less than

gt > greater than

le <= less than or equal

ge >= greater than or equal

Logical Operators

and & logical and

or | logical or

not ~ logical not

xor logical exclusive or

Control Flow

for – end for variable= expression

statements

endexample:

for i=1:10 for j=1:2:10

x(i) = i*2; y=j

end end

Control Flow

while – end x=0;

while (x<5)

x=x+s;

disp(x);

end

Control Flow

if – else – elseif – enda=6; % a=7; % a=10;

if (rem(a,3)==0)

a=a*3;

elseif (rem(a,2)==0)

a=a*2;

else

a=a*10;

end

disp (a);

Control Flow

switch – case – otherwise – endx= input (‘The value of x:’);units= input (“Enter the unit of x: (Please Enter the unit

between ‘ ‘) ’);switch units

case (‘inch’,’in’)y=x*2.54 ;

case (‘feet’,’ft’)y=x*2.54*12 ;

case (‘meter’,’m’)y=x*100 ;

case (‘millimeter’,’mm’)y=x/10 ;

otherwisedisp (‘Unknown unit’);

end

Control Flow

breakfor i=1:10

if (i>5)break;

elsea=a*4.5;

endenddisp (a);

M-files

1. Scripts : Deal with the work space directly without inputs or outputs

2. Functions: Needs inputs and only the outputs are saved in the workspace.

examples:

function [output1,output2…]=function_name(input1,input2,…) function function_name(input1,input2,…)

M-files

Function or script calling is done by typing the file name.

The function file name must be the same as function name

Function name must be one word Has a maximum of 31character size Starting by a character

M-files

Assume a function: function [a,b,c]=my_function(x,y)

is called as[b]=my_function(x,y,z);[a,b,c]=my_function(u);

then b = a value x= u value

Math functions

Basicfunctions

triangular functions

Approximation functions

complex functions

conversion functions

abs cos fix abs dec2hex

sqrt sin round angle dec2bin

mean tan floor conj dec2base

power acos ceil imag hex2dec

log asin rem real bin2dec

log10 atan floor base2dec

exp csc ceil rad2deg

max sec rem deg2rad

min cot cart2sph

sort acsc cart2pol

asec pol2cart

acot sph2cart

cosh

sinh

tanh

Exercise1. write a matlab program that sum a series

begins by 2 and ends by 100 Use both for and while loops in separated m-files

2. write a switch – case program such that: if 35>=S>20 display ‘Hot Day’ if 20>=S>10 display ‘Nice Day’ if 10>=S>=0 display ‘Cold Day ‘ otherwise display ‘Out of Range’

That S is the sum of the array M, and M is: Random matrix of size 3×6 and has values between 0 and

2 A square matrix of size 3 and values between 1 and 9 A vector of equal elements =5 and size of 7 Identity matrix of size 10×10