Basics Of Matlab 1 36g1b

MATLAB R2010a

Introduction, practice and Applications

Nikesh Bajaj Dept. of Electronics Engineering Lovely Professional University Phagwara-144402

Basics of MATLAB  

Basic Mathematic: Calculator Array and Array Operation 

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Indexing, Matrix Operations, Manipulations

Multidimensional Array Cell Array Character Strings Logical Operations Loops/switch-case/if else: PLOTS Script/M file- function and code 2

By Nikesh Bajaj

MATLAB Desktop

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Command Window 

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>> prompt when ready for a command “Busy” in lower Can use arrow keys for command history and modify commands

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Current Folder 

Current Folder Window 

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Displays contents of the current working directory for script and function files Can modify path through MATLAB function or going under File>Set Path

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Workspace and Command History 

Workspace Window   

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Shows all currently defined variables Array dimensions Min, max values

Command History  

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Shows all past commands Can copy and past commands into command window Double click will execute command 6

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HELP Window

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Basic Math/Calculator 

Basic Math operations   

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Inbuilt Functions  

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>> 4+3+5 ans =9 >> 4*2+5*3+99*2 sin, cos, tan, exp, log, log10, log2 sqrt, e10, ^

sin(30), sqrt(4), log(10) 8

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Math Functions

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Variable Naming rule 

Variable names are Case Sensitive 

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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)   

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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    

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%, ; , …

comments not displaying the result multiple commands continue to next line

a=1, c=2; b=3 X=(a+b)*3… +5 By Nikesh Bajaj

Mathematical Functions 

Trigonometric  

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--sin(30)

Powers 

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sin, sinh, asin, asind cos, tan, csc, cot, sec

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

Rounding Functions 

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round nearest int. floor -inf 14

fix 0 ceil +inf

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Complex number        

c1= 2-3i or 2-3j or 2 -3*sqrt(-1) 0r complex(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   

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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 16

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Number Theory   

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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 18

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Array (1D) 

Construction   

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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)=? 20  x(100)=? 

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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.‟ 21

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Array (2D) Matrix 

Construction  

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x=[ 1 2 ;4 5]; x=[1 2 3; 2 3]=?

Indexing    

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

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Array Operations   

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y=x-2 y=2*x-1 2*x/5+1

x and y of same size     23

x+y; %element wise x-y; x.*y x./y Q: 1./x, x./y and x.\y x.^2

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Array Operations  

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Matrix   

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1./x =? x.^y ones(r,c) zeros(r,c) x*y inv(x), rank(x), eig(x)

Matrix Manipulation  24

x(2,3)=1

x(3:6, 5:8)=0 By Nikesh Bajaj

Multidimensional Array   

x(1,1,1) y(1,1,1,1,1, . . . .) Almost every operation of 2D Arrays can be extended to 3D 4D…..nD

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Problems 

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Do arithmetic operations with different data types and conclude it Check isinteger, isnumeric, isfloat with different values

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Cell Array  

Cell Array? Construction   

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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 27

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Indexing: Array, matrix and Cell    

x=[2 3; 3 4] x(:), x(1), x(4) x(:)‟ y=reshape(x,n,m)

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Character Strings 

Construction   

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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   

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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 

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for i=1:10 end while i>10 i=i+1 end

if x==y elseif x==z end

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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) 

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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)       

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plot(x,y) stem(x,y) stairs(x,y) area bar, bar3, barh feather errorbar, rose

By Nikesh Bajaj

Plots (2D) 

Multiple functions on same plot  

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--grid on/off box off   

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plot(x1,y1,x2,y2,……) hold on hold off

axis([xmin xmax ymin ymax]) axis auto tight legend(„x1‟ „x2‟ )

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Plots (2D) 

Multiplots 

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subplot(2,2,2)

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Plots 3D 

plot3(x,y,z)  

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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 

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clc, clear , clear all date, clock quit, exit size, length max, min who, whos disp

By Nikesh Bajaj