14571_basics of matlab 1

7/28/2019 14571_Basics of MATLAB 1

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MATLAB R2010aIntroduction, practice and Applications

Nikesh BajajDept. of Electronics Engineering

Lovely Professional University

Phagwara-144402


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MATLAB Desktop

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Command Window >> prompt when ready for a

command

Busy in lower Can use arrow keys for

command history andmodify commands

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Current Folder Current Folder Window

Displays contents of the

current working directory for script and function files

Can modify path throughMATLAB function or going

under File>Set Path

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Workspace and Command

History Workspace Window

Shows all currently defined variables

Array dimensions Min, max values

Command History

Shows all past commands

Can copy and past commands intocommand window

Double click will execute command

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HELP Window

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Basic Math/Calculator Basic Math operations

>> 4+3+5

ans =9 >> 4*2+5*3+99*2

Inbuilt Functions

sin, cos, tan, exp, log, log10, log2

sqrt, e10, ^

sin(30), sqrt(4), log(10)

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Variable Naming ruleVariable names are Case Sensitive

Xyz, xyz, XYZ, XyZ all are different

Variable name should start with character only Can be followed by digit _

Punctuation and space are not allowed

Max length of name is 63 characters

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Variable Naming rule Reserve word list (Keyword)

for, end if else, elseif, function, case switch break

isvarname( ) True(1), False(0) Can not be used as variable

Special Variables

ans beep pi inf NaN

i and j

Can be used as varible

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General Purpose Commands

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Comments, Punctuations %, comments

; not displaying the result

, multiple commands

continue to next line

a=1, c=2; b=3 X=(a+b)*3

+5

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Mathematical Functions Trigonometric

sin, sinh, asin, asind --sin(30)

cos, tan, csc, cot, sec Powers

^ power, exp, log, log10, log2, sqrt,

Rounding Functions

round nearest int. fix 0

floor -inf ceil +inf

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Complex number c1= 2-3i or2-3j or2 -3*sqrt(-1) 0rcomplex(2,-3)

c2= sqrt(-2)=?

c3=7+sin(0.5)j Execute it

c4=(c1+c2)/c3

c5=real(c4)

=imag(c4)

=abs(c4)

=angle(c4)15

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Floating Points

format short

format long

precision; eps(x), eps(1), eps(10)

PROBLEM: Execute the following

0.08 - 0.5 + 0.42

0.42-0.5+0.08

0.08 +0.42 -0.5

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Number Theory

factor

isprime

prime

gcd

lcm

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DATA Types

double, single

uint8, uint16, uint32, uint64

int8, int16, int32 int64

class(x) %data type of x

isinteger, isnumeric, isfloat

char cell

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Array (1D)

Construction

x=[ 1 2 3 4 5 6 7 8 9 10 ];

x=1:10 or 1:1:10 x=linspace(1,10,10);

y=(0:0.1:1)*pi = ?

y=linspace(0,pi,11);

y=linspace(2,17,24);

z=logspace(0,2,10)=?

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Array (1D)

Indexing

x(0) error

x(1), x(4) y=x(2:7)

y=x(4:end)

y=x(1:2:end)

y=x(10:-1:1) y=x([ 3 2 1 9 10 ])

y=x([1 1 2 2 3 3 1 1 ])

x(3.4)=?

x(100)=?20 By Nikesh Bajaj


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Array (1D)

Creating an array from others

z = [x y] % appending

z =[y x] z= [x(1:2:10) 1 0 1 0]

Transpose

z=x z=x.

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Array (2D) Matrix

Construction

x=[ 1 2 ;4 5];

x=[1 2 3; 2 3]=? Indexing

x(1,1), x(1,2)

y=x(1,:)

y=x(:,1)

y=x(2:3,1:5)

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Array Operations

y=x-2

y=2*x-1

2*x/5+1

x and y of same size

x+y; %element wise

x-y; x.*y x./y

Q: 1./x, x./y and x.\y

x.^223 By Nikesh Bajaj


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Array Operations

1./x =?

x.^y

Matrix ones(r,c) zeros(r,c)

x*y

inv(x), rank(x), eig(x)

Matrix Manipulation

x(2,3)=1 x(3:6, 5:8)=0

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Multidimensional Array

x(1,1,1)

y(1,1,1,1,1, . . . .)

Almost every operation of 2D Arrayscan be extended to 3D 4D..nD

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Problems

Do arithmetic operations with different datatypes and conclude it

Check isinteger, isnumeric, isfloat withdifferent values

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Cell Array

Cell Array?

Construction

variable should not exist before.A(1,1)={[ 2 3 ; 3 4]} A(2,2)={HI}

A{1,1}=[2 3;3 4] A{2,2} =HI

celldisp(A), cell(2,3)

indexing

manipulation

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Indexing: Array, matrix andCell

x=[2 3; 3 4]

x(:), x(1), x(4)

x(:) y=reshape(x,n,m)

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Character Strings

Construction

txt=Hi my name is Bajaj

txt =[ hi hello how are you?] txt =[ hi

How are you? ]

txt= char(hi, how are you?)

Indexing and Manipulation size(txt) txt(1), txt (2,10), txt(2:5)

txt(3)=N

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Character Strings

Operations

double(txt)

char(x) txt

t=int2str(524); num2str(34.3)

str2int(32) str2num(32432.3);

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Logical Operation

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Loops/if-else

for i=1:10

end

while i>10

i=i+1

end

if x==y

elseif x==z

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find command

x=randint(1,10,3)

i=find(x), find(x>0), find(x==1)

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Plots (2D)

y=rand(1,10);

x=1:10

plot(x,y) plot(y)

title(sin wave)

xlabel(time) ylabel(Amplitude)

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plot(X1,Y1,LineSpec, )

plot(x,y,'-.or')

plot(x,y,'d')

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Plots (2D)

plot(x,y)

stem(x,y)

stairs(x,y)

area

bar, bar3, barh

feather

errorbar, rose

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Plots (2D)

Multiple functions on same plot

plot(x1,y1,x2,y2,)

hold on hold off --grid on/off box off

axis([xmin xmax ymin ymax])

axis auto tight

legend(x1 x2 )

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Plots (2D)

Multiplots

subplot(2,2,2)

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Plots 3D

plot3(x,y,z)

t=linspace(0,10*pi)

plot3(sin(t), cos(t),t) Meshgrid

x=sin(2*pi*t), y=x*x;

[X Y]=meashgrid(1:101,1:101);

plot3(X,Y,y)

surf(y)

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M file/script/function

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General Purpose Commands

clc, clear , clear all

date, clock

quit, exit size, length

max, min

who, whos

disp

14571_basics of matlab 1

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