Extra Material Matlab

7/25/2019 Extra Material Matlab

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MATLAB Basics The Reference

Durga Lal Shretha

Yunqing Xuan


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Part-1

2


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copyright Durga Lal Shrestha

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Entering Matrices

Enter an explicit list of elements

A = [10 20 30; 1 2 3; 2 4 8];

Load matrices from external data files

A = load('mymagic.txt'); % you need to create the file before

hand

Generate matrices using built-in functions.

A = magic(4)

Create matrices with your own functions in M-files.

A = myfunction(input1,input2) %


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Enter an explicit list of elements

Separate the elements of a row with blanks or commas.

Use a semicolon, ; , to indicate the end of each row.

Surround the entire list of elements with square brackets,[ ].


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Subscripts

Using parenthesis (row,column)

e.g. the element in row I and column j of A = A(i,j)


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The colon operator :

To generator vector

Unit steps startvalue:endvalue

Nonunit steps with the given increment

startvalue:stepvalue:endvalue


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The colon operator : To select subarrays (portion ofmatrix)


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Selecting subarrays: Common errors


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Generating Matrices

Zeros

Ones


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Generating Matrices

rand - uniform random number between 0 and 1

randn normal random number(0,1)


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Concatenation

Concatenation is the process of joining small matrices to

make bigger ones. Using []


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Deleting Rows and Columns


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Reordering data


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Changing data


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Arrays

Scalars: zero dimensional or 1 by 1

S = 2.3

Vector: one dimensional (i.e. n by 1 or 1 by n)

V = [1 4 3 5 6]

Matrix: two dimensional (i.e. m by n)

M = [1 2 3

4 5 6]

Array: N dimensional


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Multidimensional Array


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size, length, ndims


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Matrix Algebra

Addition

Subtraction

Matrix multiplication

Array multiplication


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Addition

+

A and B must have the same size, unless one of them isa scalar


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Subtraction

-



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Matrix Multiplication

*

For nonscalar A and B, the number of columns of A must

equal the number of rows of B. A scalar can multiply a matrix of any size.


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Array Multiplication

.*

element-by-element product of the arrays A and B



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Part 2


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Expressions

Variables

Numbers

Operators

Functions


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Numbers

MATLAB uses conventional decimal notation, with anoptional decimal point and leading plus or minus sign, fornumbers.

Scientific notation uses the letter e to specify a power-of-ten scale factor.

Imaginary numbers use either i or j as a suffix.

Some examples of legal numbers are

3 -99 0.0001

9.6397238 1.60210e-20 6.02252e23

1i -3.14159j 3e5i


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Functions

MATLAB provides a large number of standard elementary

mathematical functions, including abs, sqrt, exp, and sin. For a list of the mathematical functions, type

help elfun for Elementary functions (Trigonometric, Exponential,Complex, and Rounding and remainder)

help specfun for Specialized math functions (e.g. gamma, factor

etc) help elmat for Elementary matrices and matrix manipulation (e.g.

zeros, size, reshape, magic etc.)

Built-in functions are part of the MATLAB core so they

are very efficient, but the computational details are notreadily accessible (e.g sin, sqrt etc).

Other functions, like gamma and sinh, are implementedin M-files and you can see the code and even modify it ifyou want.


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Data Types


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Numeric Types

Numeric data types in MATLAB include signed andunsigned integers, and single- and double-precisionfloating-point numbers.

Integers


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Floating-Point Numbers

Double-Precision Floating Point

MATLAB default data type

64 bits, large memory and more precision

Single-Precision Floating Point

32 bits, less memory and less precision


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Complex Numbers

>> x = 2 + 3i

x =

2.0000+3.0000i

>> z = complex(2.1, pi)

z =2.1000 + 3.1416i

>> zr = real(z)

zr =

2.1000

>> zi = imag(z)

zi =

3.1416


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Infinity and NaN

Infinity

x = log(0);

>> isinf(x)

ans =

1

NaN (Not a Number)

MATLAB represents values that are not real or complex numberswith a special value called NaN

0/0 and inf/inf


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Display Format for Numeric Values

By default, MATLAB displays numeric output as 5-digitscaled, fixed-point values.

You can change the way numeric values are displayed toany of the following:

5-digit scaled fixed point, floating point, or the best of the two

15-digit scaled fixed point, floating point, or the best of the two

A ratio of small integers

Hexadecimal (base 16)

Bank notation

Format short (formatting to 5 digit) Check the current format setting:

get(0, 'format')

ans =

short


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Format

x = [4/3 1.2345e-6]

x =

1.3333 0.0000

format short e

xx =

1.3333e+000 1.2345e-006

format long

xx =

1.33333333333333 0.00000123450000


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Logical Types

The logical data type represents a logical true or falsestate using the numbers 1 and 0, respectively.

(5 * 10) > 40

ans =

1

Vector of logical [30 40 50 60 70] > 40

ans =

0 0 1 1 1


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Logical Types

Using Logicals in Conditional Statements

str = 'Hello';

if ~isempty(str) && ischar(str)

sprintf('Input string is ''%s''', str)

end

ans =

Input string is 'Hello'


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Logical Indexing


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Part 3


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Characters and Strings

Padding.


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Structure Array

Structures are MATLAB arrays with named data

containers called fields.

The fields of a structure can contain any kind of data.


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Structure Array


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Structure Array

strArray = struct('field1',val1,'field2',val2, ...)

ll


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Cell Arrays

A cell array provides a storage mechanism for dissimilar

kinds of data.

C ll


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Cell Arrays

Use { } for constructing, concatenating and indexing

A = {[1 4 3; 0 5 8; 7 2 9], 'Anne Smith'; 3+7i, -pi:pi/4:pi}

A =

[3x3 double] 'Anne Smith'[3.0000 + 7.0000i] [1x9 double]


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Part 4

Data Import and Export

D t


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Supported Types of Data

Binary data from a MATLAB session

Text data

Graphics files

Audio and audio/video data

spreadsheets Data from the system clipboard

Information from the internet


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Load command


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Load command


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Part 5

MATLAB Graphics

Matlab Graphics


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Matlab Graphics

Plotting Process

Graph Components

Figure Tools

Arranging Graphs Within a Figure

Selecting Plot Types

Plotting Process


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Plotting Process

Use plotting tools to create graphs interactively.

plottools

Use the command interface to enter commands in theCWD or create plotting programs.

x = 0:0.1:2*pi;

plot(x,sin(x)

Graph Components


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Graph Components

Figure

Plot

Axis

Data

Figure Tools: Figure Palette Plot Browser and Property Editor


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Figure Tools: Figure Palette, Plot Browser and Property Editor



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Basic Plotting Functions


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Basic Plotting Functions

Plotting Steps


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Plotting Steps

Plotting Multiple Data Sets in One Graph


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Plotting Multiple Data Sets in One Graph

plot(x,y)

hold on

plot(x,sin(x-0.5),'r')

plot(x,sin(x-0.25),'g')

OR

Line Styles and Colors


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Line Styles and Colors

plot(x,y,'--rs','LineWidth',2,...'MarkerEdgeColor','k',...'MarkerFaceColor','g',...

'MarkerSize',10)

Contour plots


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Contour plots

Twenty contours of the peaks function

-3 -2 -1 0 1 2 3-3

-2

-1

0

1

2

3

Contour


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Contour

Contour3


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Contour3

-3-2

-10

12

3

-2

0

2

-10

-5

0

5

10

Twenty Contours of the peaks Function


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Plotting Matrix Data


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Plotting Matrix Data

Plotting Image Data


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Plotting Image Data

100 200 300 400 500

100

200

300

400

500

600

Surface plot


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Surface plot

-10

-5

0

5

10

-10

-5

0

5

10-0.5

0

0.5

1

Surface plot


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Surface plot

Creating Stream Particle Animations


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Creating Stream Particle Animations


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Part 6

Program components

Basic Program Components


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Basic Program Components

Variables

Keywords

Special Values

Operators

MATLAB Expressions Program Control Statements

Symbol Reference

MATLAB Functions

Variables


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Variables

A MATLAB variable is essentially a tag that you assign to

a value while that value remains in memory. Local Variables (local to functions)

Global Variables (share a single copy of a variable)

Persistent Variables (retained value from one function call to the

next)

Naming Variables


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a g a ab es

Any combination of characters, numbers and underscore

(starting with characters) Case sensitive

e.g. Variable1, variable1 are different

MATLAB uses only the first N characters of the name and

ignores the rest, where N = namelengthmax(63)

The genvarnamefunction can be useful in creatingvariable names that are both valid and unique.

E.g. four similar variable name strings that do not conflict witheach other: v = genvarname({'A', 'A', 'A', 'A'})

v = 'A' 'A1' 'A2' 'A3'

Keywords


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y

MATLAB reserves certain words for its own use as

keywords of the language. To list the keywords, type iskeyword

'break 'case'

'catch 'continue'

'else 'elseif' 'end 'for'

'function 'global'

'if 'otherwise'

'persistent 'return' 'switch 'try'

'while'

Special Values


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p

Operators


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p

Arithmetic Operators

Relational Operators

Logical Operators

Arithmetic Operators


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p

Relational Operators


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p

Logical Operators


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g p

Operator Precedence


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p

Parentheses ()

Transpose (.'), power (.^), complex conjugate transpose (), matrixpower (^)

Unary plus (+), unary minus (-), logical negation (~)

Multiplication (.*), right division (./), left division (.\), matrixmultiplication (*), matrix right division (/), matrix left division (\)

Addition (+), subtraction (-)

Colon operator (:)

Less than (=), equal to (==), not equal to (~=)

Element-wise AND (&) Element-wise OR (|)

Short-circuit AND (&&)

Short-circuit OR (||)


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Program Control Statements


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Program control is divided into four categories:

Conditional Control if, switch

Loop Control for, while, continue, break

Error Control try, catch

Program Termination return

Conditional Control if


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if logical_expression

statementsend

if logical_expression1

statements1

elseif logical_expression2

statements2

else

statements3

end

Conditional Control switch, case, and otherwise


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Loop Control for


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The for loop executes a statement or group of

statements a predetermined number of times.

for index = start:increment:end

statements

end

Loop Control while


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The while loop executes a statement or group of

statements repeatedly as long as the controllingexpression is true.

Loop Control continue


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The continue statement passes control to the next

iteration of the for or while loop in which it appears,skipping any remaining statements in the body of theloop.

Loop Control break


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The break statement terminates the execution of a for

loop or while loop.

Error Control- try and catch


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Error control statements provide a way for you to take

certain actions in the event of an error.

Program Termination return


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Program termination control enables you to exit from

your program at some point prior to its normaltermination point.


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Part 7

Symbol Reference

Symbol Reference


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At @ for fhandle = @myfun

Colon :

Comma ,

Curly Braces { }

Dot .

Dot-Dot-Dot (Ellipsis) ... on page 3-103

Exclamation Point ! for Shell Escape (e.g. !dir) Parentheses ( ) for array indexing and function input arguments

Percent % and Percent-Brace %{ %}

Semicolon ;

Single Quotes for character and string

Space Character

Square Brackets [ ]

Colon :


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Numeric Sequence Range and Step

Indexing Range Specifier

Conversion to Column Vector

Preserving Array Shape on Assignment

Comma ,


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Row Element Separator

Array Index Separator

Function Input and Output Separator

Command or Statement Separator

Curly Braces { }


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Cell Array Constructor

Cell Array Indexing

Dot .


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Structure Field Definition

Object Method Specifier

Dot-Dot-Dot (Ellipsis) ...


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Line Continuation

Entering Long Strings

You cannot use an ellipsis within single quotes to continue a

string to the next line:

Percent % and Percent-Brace %{ %}


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Single Line Comments

Conversion Specifiers

Block Comments

Semicolon ;


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Array Row Separator

Output Suppression

Command or Statement Separator

Space Character


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Row Element Separator

Function Output Separator

Square Brackets [ ]


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Array Constructor

Concatenation

Function Declarations and Calls


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Part 8

M-File Programming

Scripts and Functions


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There are two kinds of M-files.

Scripts, which do not accept input arguments or returnarguments. They operates on data in the workspace

Functions are M-files that can accept input arguments

and return output arguments. Functions operate on variables within their own workspace,

separate from the base workspace.

The names of the M-file and of the function should be the same.

Scripts: small exercise


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Create a file called magicrank.m

Functions


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Create a file called fmagicrank.m

help fmagicrank

type mr = fmagicrank(10);

Basic Parts of an M-File


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Creating a Simple M-File


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1. Create an M-file using a text

editor.function c = myfunc(a,b)

c = sqrt((a.^2)+b.^2))

x = 7.5;

y = 3.342;

z = mufunc(x,y)

z =

8.2109

2. Call the M-file from the

command line or from within

another M-file

Types of Functions


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Primary M-File Functions - the first function in an M-file andtypically contains the main program.

Subfunctions - subroutines to the main function or to definemultiple functions within a single M-file.

Nested Functions - functions defined within another

function. They can help to improve the readability of the programand to give more flexible access to variables in the M-file.

Anonymous Functions - provide a quick way of making a

function from any MATLAB expression. We can compose anonymousfunctions either from within another function or at the MATLABcommand prompt.

Overloaded Functions - useful when you need to create a

function that responds to different types of inputs accordingly.

Private Functions - a way to restrict access to a

function. You can call them only from an M-file function in theparent directory.

Constructing an Anonymous Function


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Subfunctions


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Exercise Function


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function [Y] = filterdata(data,thres)

[NRow,NCol]=size(data);j=1;

Y=[];

for i=1:NRow

if data(i)>=thres

Y(j)=data(i);

j=j+1;

end;end;

Function Handles


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A function handle is a MATLAB value that provides a

means of calling a function indirectly Construct a function handle in MATLAB using the at sign,

@, before the function name.

fhandle = @sin;

You can call a function by means of its handle in thesame way that you would call the function using itsname.

The syntax is fhandle(arg1, arg2, ...);

fhandle(0.50)

Function Functions


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One function works on another functions

Zero finding Optimization

Quadrature

Ordinary differential equations

Humps function


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hold on; plot(p,humps(p),'r*');


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Q = quadl(@humps,0,1)

Q =29.8583

Z = fzero(@humps,0.5)

Z =-0.1315

Z = fzero(@humps,1)

Z =1.2955

f = humps(Z)

f =0


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Part 9: GUIDE

Simple Graphical User Interface

GUIDE


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GUIDE, the MATLAB graphical user interfacedevelopment environment, provides a set of tools for

creating graphical user interfaces (GUIs).

Simple gui example


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Simple gui example


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Simple gui example


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Simple gui example


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