Base Class PPT

7/25/2019 Base Class PPT

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BASICS OF


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Introduction

MatLab : MatrixLaboratoryDr.CleveMolder

MATLABis

an

interpreted

language

no

compilation

nee

possible)

NumericalComputationswithmatrices

WhyMatLab? UserFriendly(GUI)

Easytoworkwith

Powerfultoolsforcomplexmathematics

MatLab hasextensivedemoandtutorialstolearnbyyou

Usehelp

command


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Features Donthavetodeclaretype Dont

even

have

to

initialise

Dynamicmemoryallocation

Basiccomputation

unit

is

amatri

Indexingstartsfrom1insteadof

Great

visualisation

capabilities Loadsofbuiltinfunctions Easytolearnandsimpletouse


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TheMATLABInterfaces

Workspace

Command History


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CreatingVariables

Itcan

be

any

string

of

upper

and

lower

cas

ongwithnumbersandunderscoresbutitnwithaletter

Reservednames

are

IF,

WHILE,

ELSE,

ENDtc.

Namesarecasesensitive

Thevariables

are

1x1

matrices

with

double

[Datatypes..]

>>a=12;

%variable

ais

assigned

12

N


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SingleValues

Singletons Toassignavaluetoavariableusetheequals

ymbol=

>>A=32

Tofind

out

the

value

of

avariable

simply

type

thenamein

Thevalueoftwovariablescanbeaddedtogether,andtheresultdisplayed

>>

A

=

10

>>

A

+

A

ortheresultcanbestoredinanother

variable>>A=10

>>

B

=

A

+

A


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NumericTypes

Numeric classes includes signed and unsigned integers, and

ion and double-precision floating-point numbers

By default MATLAB stores all numeric values as double-prec

point


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Vectors

Avector

is

alist

of

numbers

Usesquarebrackets[]tocontainthenumbers

Tocreatearowvectoruse,toseparatethecontent

Tocreateacolumnvectoruse;toseparatethecontent


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Arowvectorcanbeconvertedintoacolumnvectorbyusingt

transposeoperator

o Max(),min();

max/mi

o Std(),var();standarddeviatio

o Sum(),prod(); sum/pr

o

Sort();

sort

in

ao Mean(),median();

o linspace(a,b,n);

Try this ??

Vectors


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The:operator

VERY

important

operator

in

Matlab Meansto

>>1:10

ans=

1

2

3

4

5

6

7

8

9

10>>1:2:10

ans=

1 3 5 7 9

10

Try

>>

>>


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Matrices

Dontneedtoinitialisetype,ordimensions>>A=[321;510;217]

A=

3 2 1

5 1 0

2

1

7>>

Listthenumbersusing,toseparateeachcolumnand

then;todefineanewrow

11

square brackets to define matrices

semicolon for next row in matrix


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MatrixIndex

Thematrixindicesbeginfrom1(not0 (asinC))

The

matrix

indices

must

be

positive

integerGiven:

A(-2), A(0)

Error: ??? Subscript indices must either be real positive integers or logicals.

A(4,2)Error: ??? Index exceeds matrix dimensions.

>> A

ans =

3

6

2

5

87

3

2

3


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ChangingMatrix

Rows

or

Colum

To change all of the values in a row or column to use

>> results :, 3) = 0 >> results :, 5) = results :, 3

>> results 3, :) = [10, 1

>> results :, 3) = [1; 1;

Try this ??


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ManipulatingMatrices

>>A' %transpose

>>B*A

%

matrix

multiplication>>B.*A%elementbyelementmultiplication

>>B/A %matrixdivision

>>B./A %

element

by

element

divisio>>[BA] %Joinmatrices(horizontally

>>[B;A] %Joinmatrices(vertically)

14

Create matrices A and B and try out the thein this slide

Enter maB into thMatlabworkspac


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MatricesOperationsGiven A and B:

Addition Subtraction Product Transpose

>>>>>


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Theuseof. ElementOperatio

K= x^2Erorr:??? Error using ==> mpower Matrix must be square.

B=x*y

Erorr:??? Error using ==> mtimes Inner matrix dimensions must agree.

A = [1 2 3; 5 1 4; 3 2 1]A =1 2 35 1 4

3 2 -1

y = A(3 ,:)

y=3 4 -1

b = x .* y

b=3 8 -

3

c = x . / y

c=0.33 0.5 -

3

x = A(1,:)

x=1 2 3


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ConcatenationofMatrices

x=[12],y=[45],z=[00]

A=[xy] %HorizontalConcatenation

1 2 4 5

B

=

[x

;

y]

%

Vertical

concatenation

12

45

C = [x y ;z]Error:??? Error using ==> vertcat CAT arguments dimensions are notconsistent.


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BasicMatrixFunctions

zeros(m, n) : matrix w

ones(m, n) : matrix w

eye(m, n) : the iden

rand(m, n) : uniform

randn(m, n) : norma

magic(m) : square

have therow, colu

pascal(m) : Pascal

18

Inv (A); % inverse of A

sum(A); %summation.

Rank(A); % rank of matrix A

A %transpose of A

Det (A) %determinant

dot(a,b) %dot product of two vectors

Cross(a,b) %cross product of two vectors

V= eig (A) % eigenvalue vector of A

Size(A): % return [m n]

Length(A): % length of a vector

max(size(A));

B = A(2:4,3:5); % B is the subset of A

A(:, 2)=[]; % Delete second column

Creating Ma


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Operators(relational,logica

==Equalto

~=Not

equal

to

Strictly

greater

=Greater

than

equal

to

&Andoperator

|Or

operator


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ScriptsandFunctions

There are two kinds of Mfiles:

Scripts, which do not accept input argumenttput arguments. They operate on data in the

Functions, which can accept input argumen

output arguments. Internal variables are locion.


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FlowControl

if

for

while

break

C l S


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ControlStructures

If

Statement

Syntax

if

(Condition_1)Matlab Commandselseif (Condition_2)

Matlab Commandselseif (Condition_3)Matlab Commands

else Matlab Commandsend

Some Dummy E

if ((a>3) & (b==5))

Some Matlab Comend

if (a


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Control Structures

Forloopsyntax

fori=Index_Array

Matlab Commandsend

Some Dummy

for i=1:100

Some Matlab Cend

for j=1:3:200

Some Matlab C

end

for m=13:-0.2:-21

Some Matlab C

end

for k=[0.1 0.3 -13

Some Matlab C

end


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ControlStructures

While

Loop

Syntax

while(condition)

Matlab Commands

end

Dummy Exam

while ((a>3) & (

Some Matlab

end


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VisualizationandGraphics

plot(x,y),plot(x,sin(x)) plot1Dfunction

figure,figure(k)

open

anew

figure

holdon,holdoffrefreshing

mesh(x_ax,y_ax,z_mat)

viewsurface

contour(z_mat) viewzastop.map

subplot(3,1,2)

locateseveral

plots

in

figu

axis([xmin xmax ymin ymax])changeaxe

title(figuretitle)

add

title

to

figure

Documents

Base Class PPT