Getting Started with MATLAB: Slides

Getting Started with MATLAB

PsiPhiETC

www.psiphi.in

January 1, 2012

PsiPhiETC (www.psiphi.in) Getting Started with MATLAB January 1, 2012 1 / 74

Motivation

Why are you interested in MATLAB?

Driven byPresent AssignmentCuriosityUrge for Value Addition

Reason

Belief

Action Reward

Motivation

What is MATLAB?

MATrix LABoratoryHigh-performance scientific computationMATLAB System Integrates

1 Computation2 Visualization3 Programming

in an easy-to-use environmentMATLAB System Consists of

1 Desktop Tools and Dev Environment2 Mathematical Functions Library3 Programming4 Graphics5 External Interface

Motivation

Features of MATLAB!

Library of Mathematical FunctionsInteractive Computations throughCommand WindowProgramming for Complex ProblemsGraphics for Data Analysis andVisualizationGraphical User Interface (GUIDE)Specialized Toolboxes (Simulink)

Motivation

Course Contents

# Topic Reference1 Introduction RP Ch1&22 Getting Started RP Ch23 Interactive Computation RP Ch34 Programming and Scripts RP Ch45 Programming and Functions RP Ch46 Graphics-1 RP Ch67 Graphics-2 Notes8 GUIDE & Simulink Notes

No Promise, only Opportunity! No Teaching, only Learning!

Motivation

Installation

Available for all major computingplatforms (Windows, Unix, Mac)World Wide Web:http://www.mathworks.com

Student and Professional VersionsRead the installation instructionscarefullyCheck Installation

Motivation

Desktop Tools & Development Environment

Menu [Desktop Tools (Layout), Help Browser], Editor, Current Directory [pwd,ls, window, M-Lint], Command Window [x=1, Workspace, x+1, ans], CommandHistory [Selection, Execution], Docking, Start, Ref:GSG-Ch7

Motivation

Ways to Get Help!

Extensive and excellentdocumentationHelp Browser

DemosSearch

Commands:lookfor ’string’help topicwhich topic

edit, H1 Line, Help, Code

1 >> lookfor mean2 >> help mean3 >> which mean4 >> edit mean

Motivation

Some General Commands

clc clears command windowclf clears figureclear: multiple variable, all variablescd change directorydir show directory contentspath [pwd, directories in path]copyfile copies filesmkdir make directorydate display datequit quit matlabdiary records the sessionsmart recall

1 >> diary2 >> pwd3 >> clc4 >> x=2;y=3;5 >> clear x6 >> clear all

Motivation

Vectors and Scalars

Variable Namesrow vec ( [], col sep), col vec(row sep)’, . . . , ;a : ∆ : blinspace(a,b,n)+, -, cross, dot, .* , ./, .^sin, cos, log, sqrtformat

1 >> rv=[1,2,3]2 >> cv=[1;2;3]3 >> v1=1:1:34 >> v2=linspace(1,3,3)5 >> v3=v1'6 >> v4=v1+v27 >> v5=v1.*v28 >> v6=sqrt(v1)9 >> format long e

Motivation

Simple Plots

plot (x,y)axis tight | equalxlabel (’string’)ylabel (’string’)title (’string’)grid on | off

1 x=linspace(0,2*pi,100);2 y=sin(x);3 plot(x,y);4 xlabel('x');5 ylabel('sin(x)');6 title('x vs sin(x)');7 axis tight;grid on;

Motivation

MATLAB Editor

Menu BarTool BarEditing SpaceLine NumberCode AnalysisMessageDocument BarStatus BarExecution andDebugging

Motivation

MATLAB Script

% for commentsH1 Line, HelpValid MATLABcommands andexpressionsComment %, KeywordsSavingExecution

1 % Script to find triangle area2 % The help for ScriptExample.m3

4 base=2; %triangle base5 height=1; %triangle height6 Area=(1/2)*base*height;

1 >> lookfor triangle2 >> help ScriptExample3 >> ScriptExample4 >> base5 >> height6 >> Area7 >> clear all

Motivation

MATLAB Functions

function[argout]=FN(argin)H1 Line% for commentsSavingexist (FN)argin pass by valuevariable are local

1 function [A]=FunctionExample(b,h)2 % FunctionExample for triangle area3 % The help for FunctionExample.m4 % Syntax A=FunctionExample(b,h)5

6 A=(1/2)*b*h;

1 >> base=2;height=1;2 >> Area=FunctionExample(base,height);3 >> b4 >> h5 >> A6 >> Area

Interactive Computations

Matrix Creation?

Enclosed within square bracket []Entered row wiseColumn Separator: space or ,Row Separator: ;. . . (ellipsis) is used for continuation

1 >> A=[1, 2, 3; 4, ...5, 6]

2 A =3 1 2 34 4 5 6

Matrix Indexing

A(i,j)=aij

size(A)=[m,n]

A(m1 : m2,n1 : n2) =

am1n1 . . . am1n2...

......

am2n1 . . . am2n2

A(:,k:end)

1 >> A=[1,2,3;...2 4,5,6]3 >> size(A)4 >> A(2,3)5 >> A(1:2,2:3)6 >> A(2,2:end)7 >> A(:,2:end)

Matrix Manipulation

Element: A(i,j)=aij

Row: A(m,:)=v1×n

Column: A(:,n)=vm×1

Submatrix: A(m1 : m2,n1 : n2) =B(m2−m1)×(n2−n1)

Appending: A=[A, vm×1], A=[A; v1×n]Deleting: A(m,:)=[], A(:,n)=[]eye(m,n), zeros(m,n), ones(m,n),magic(n)

1 >>A=[1,2,3;4,5,6];2 >>A(1,2)=9;3 >>A(2,:)=[9,9,9]4 >>A(:,3)=[9;9]5 >>A(1:2,2:3)=[9,9;9,9]6 >>A(3,:)=[9,9,9];7 >>A(:,4)=[9;9;9];8 >>A(3,:)=[]9 >>A(:,4)=[]

10 >>eye(3)11 >>zeros(3)12 >>ones(3)13 >>magic(3)

Matrix Operations

Arithmetic: +, -, *, /, ^Relational: <, >, <=, >=, ==, ∼=

Logical Operations: &, |, NOT ∼Logical Functions: all, any, exists,isempty, isinf, isnan

1 >> A=eye(2,2)2 >> B=ones(2,2)3 >> C=A*B4 >> R1=A<B5 >> R2=A==B6 >> R3=A 6=B7 >> L1=A&B8 >> L2=A|B9 >> F1=all(A)

10 >> F2=any(A)11 >> F3=isempty(A)

Elementary Maths Functions

Trigonometric: sin , asin, . . .Exponential: exp , log, . . .Algebraic: sqrt, nthroot, . . .Complex: abs, angle, conj, img, realRound-off: floor, ceil, fix, mod, remMatrix: expm, sqrtm

1 >> sin(pi/6)2 >> exp(1)3 >> sqrt(2)4 >> z=1+i5 >> abs(z)6 >> angle(z)7 >> floor(1.9)8 >> ceil(1.1)9 >> A=ones(2,2)

10 >> expm(A)

Character Strings

Single Quote: ’string’Manipulating stringevalnum2str, str2numlower, upperstrcmp, strncmpstrcat, findstr

1 >> s='Hello World'2 >> s(2)='E'3 >> eval('x=2*3')4 >> y='2.3'5 >> zn=str2num(y)6 >> zs=num2str(x)7 >> s1=lower(s)8 >> s2=strcat(s,s1)9 >> strcmpi('Hello','hello')

10 >> findstr(s,'W')

Saving and Loading Data

matlab.matsavesave (’fn’,’vn’)loadload datafile.txtd=load (’datafile.txt’)

1 >> x=linspace(0,2*pi,10)2 >> y=sin(x)3 >> save4 >> clear all5 >> load6 >> save('myfile','x')7 >> clear all8 >> load myfile9 >> load datafile.txt

10 >> d=load('datafile.txt')

Programming in MATLAB

Script Files

.m file containing validcommandsName shall starts with a letterand can have letters, digitsand _Avoid clash with names ofbuilt-in function (exist(’fn’))Variable Name 6= File NameWorks on global workspacevariablesUse of clear all

1 % solvex.m (Ref: RP)2 % 5 x1+2r x2+r x3=23 % 3 x1+6 x2+(2r-1) x3=34 % 2 x1+(r-1) x2+3r x3=55 A=[5, 2*r,r;3, 6, 2*r-1; ...

2, r-1, 3*r];6 b=[2;3;5];7 x=A\b

1 r=1;2 solvex

Function Files

function[argout] =FunctionName (argin)Local VariablesPass-by valueReadability: H1, helpModularity: subfunctionRobustness: nargin,error(‘message’)Expandability: varargin

1 function [det_A, x]=solvexf(r)2 % SOLVEXF solves eqn with par r3 % Function file solvexf.m4 % To call this function, type:5 % [det_A,x]=solvexf(r)6 % r is i/p and det_A & x are o/p7

8 A=[5, 2*r, r; 3,6, 2*r-1; 2, ...r-1, 3*r];

9 b=[2;3;5];10 det_A=det(A);11 x=A\b;

Control Flow: if-elseif-else

1 if expression2 statements3 elseif expression4 statements5 else6 statements7 end

1 if I == J2 A(I,J) = 2;3 elseif abs(I-J) == 14 A(I,J) = -1;5 else6 A(I,J) = 0;7 end

Control Flow: for loops

1 for variable = expression2 statement(s)3 end

1 sum=0;2 for i=1:1003 sum=sum+i;4 end

Control Flow: while loops

1 while expression2 statements3 end

Example of while loop,

1 v=1; num=1; i=1;2 while (num≤4096)3 v=[v;num];4 i=i+1;5 num=2^i;6 end7 v

Control Flow: switch-case-otherwise

1 switch flag2 case val1 block 1 computation3 case val2 block 2 computation4 otherwise last block computation5 end

1 color= input('color= ','s');2 switch color3 case 'red' c=[1, 0, 0];4 case 'green' c=[0, 1, 0];5 case 'blue' c=[0, 0, 1];6 otherwise error('invalid')7 end

break, continue and return

break terminates for or while loopcontinue pass control to the nextiteration of for or while loopreturn return to invoking function

Interactive Input: input, keyboard and pause

Age=input(‘Age plz?’)Name=input(‘Name plz?’, ’s’)script/function keyboard k �statements returnpause, pause(n)

1 Age=input('Age Plz?');2 Name=input('Name Plz?','s');3 keyboard;4 >> Age5 >> Name6 k>> Age=217 k>> Name='ABC'8 k>> return9 pause(10)

10 disp(Age)11 disp(Name)

Input/Output

fid = fopen (fn, r|w|a)fclose (fid)fprintf (fid, format, x)x=fscanf (fid, format)sscanf, sprintffgets, fgetl

1 fid=fopen('a.txt','w');2 fprintf(fid,'pi=%10.8f \n',pi);3 s=sprintf('e=%10.8f\n',exp(1));4 fprintf(fid,s);5 fclose(fid);6 fid=fopen('a.txt','r');7 s1=fgets(fid);8 s2=fgetl(fid);9 PI=sscanf(s1,'pi=%f');

10 E=sscanf(s2,'e=%f');

Creating Graphics Programmatically

Figure

h=figureh=gcffigure(h)Edit > Figure PropertiesProperty Editor > Figure

Name: ’string’Color: [r,g,b], (r ,g,b) ∈ [0,1]NumberTitle: {on}|off

More PropertiesMenubar: {figure}|nonePosition: [x,y,w,h]

Setting Figure Properties

h=figure or h=gcfget (h) -> ‘PropertyName’,PropertyValueget (h) -> ‘PropertyName’{PropertyValueActive} |PropertyValueOptionalset (h, ’PropertyName’,PropertyValue)

1 set (h,'Name','myName')2 set (h,'NumberTitle','off')3 set (h,'Menubar','none')4 set (h,'Color',[1,0,0])5 set (h, 'Position', ...

[500,200,400,300])

axesa=axes –> Handle aa=axes(’PropertyName’,PropertyValue)Important Properties:

ColorFontSize,FontWeight, . . .LineWidth, . . .XGrid, YGridXLim, YLimXTick, YTickXTickLabel,YTickLabel

1 a=axes;2 get(a);

Setting Axes Properties

p=axes()get (p)set (p)set (p,’PropertyName’,PropertyValue)

1 set (a, 'Color' , [1,1,0])2 set (a, 'LineWidth' , 3)3 set (a, 'XGrid' , 'on')4 set (a, 'YLim' , [-1, 1])5 set (a, 'XTick' , [0.2,0.6,0.9])6 set (a,'XTickLabel',{0.2,'six',0.9} )7 set (a, 'YTick' , [0.3,0.6,0.9])8 set (a,'YTickLabel',{'y1',0.6,'y_2'} )

plot (y)plot (x,y)plot (x,y,’LineSpecs’)

Color: r,g,b,. . .LineStyle: -, –, . . .MarkerStyle: *, + . . .

plot (x,y, ’LineSpecs’,’PropertyName’,PropertyValue)LineStyle, LineWidth, Marker,

MarkerSize

1 x=0:10;2 y=x.^2;3 plot(x,y,'r-*', ...

'Linewidth', 3,...'MarkerSize', 12)

Setting Plot Properties

p=plot (x,y)get (p)set (p)set (p, ’PropertyName’,PropertyValue)

1 x=0:10;y=x.^2;2 p=plot(x,y);3 set(p , 'Color' , [0,1,0]);4 set(p , 'LineWidth' , 3);5 set(p , 'LineStyle' , '-');6 set(p , 'Marker' , 'o');7 set(p , 'MarkerSize' , 12);

Overlay Plot

plot (x1,y1,x2,y2)plot ( x1,y1,’LS1’, x2,y2,’LS2’)plot (x1,y1,’LS’, ’PropName’,PropValue)hold onplot (x2,y2, ’LS’, ’PropName’,PropValue)hold off;line (x, y, ’PropName’,PropValue)

1 x1=-5:5; y1=x1.^2;2 x2=-5:5; y2=x2.^3;3 p1=plot(x1,y1,'r-*');4 set(p1,'Linewidth',3);5 hold on;6 p2=plot(x2,y2,'b:o');7 set(p2,'Linewidth',4);8 hold off; grid on;9 set(gca,'Linewidth',2);

Text on Plot

text(x,y,’string’)text(x,y,’string’,’PropertyName’,PropertyValue)t=text(x,y,’string’)get(t) , set (t)set (t,’PropertyName’,PropertyValue)gtext (’string’)gtext (’string’,’PropertyName’,PropertyValue)To Get Coordinate of a point:[x,y]=ginput (1)

1 x=0:10;y=x.^2;plot(x,y);2 t=text(1,20, 'P(1,20)');3 set(t,'FontSize',14);4 [x1,y1]=ginput(1);5 t1=text(x1,y1,'(x1,y1)')6 gtext('gtext','FontSize',14);

axis ([xmin, xmax, ymin, ymax])axis equalaxis squareaxis tightaxis normal

Semi Control of Axis:axis (xmin,inf,-inf,ymax)

1 x=linspace(0,2*pi,100);2 y=sin(x);3 plot(x,y);4 axis([0,2*pi,-1,1]);

Legend

legend (’string’)legend (’string1’,’string2’,. . . )legend (’string1’,’string2’,. . . ,’PropertyName’,PropertyValue)

1 x1=-5:5; y1=x1.^2;2 x2=-5:5; y2=x1.^3;3 p=plot(x1,y1,'r',x2,y2,'g');4 set(p,'Linewidth',4);5 l=legend('data x1-y1', ...

'data x2-y2');6 set(l,'Location','NorthWest');

Subplot

subplot (m,n,p)m: Number of rowsn: Number of columnsp: plot number

1 x1=-5:5; y1=x1.^2;2 x2=-5:5; y2=x2.^3;3 subplot (1,2,1);4 plot (x1,y1,'g','Linewidth',3);5 subplot (1,2,2);6 plot(x2,y2,'r','Linewidth',3);

Findobj

h=findobjh=findobj (’PropertyName’,’PropertyValue’)h=findobj (ObjectHandles,’PropertyName’,’PropertyValue’)

1 x1=-5:5; y1=x1.^2;2 x2=-5:5; y2=x2.^3;3 plot (x1,y1,'r',x2,y2,'g');4 h1=findobj('Color','r');5 set(h1,'Linewidth',3);6 h2=findobj('Color','g');7 set(h2,'Color','b','Linewidth',3);

Creating Graphics Interactively

Graphics Objects Hierarchy

FigureAxesPlot ObjectsAnnotation Objects

Plotting Process

Creating GraphExploring DataEditing Graph ComponentsAnnotation GraphsPrinting and Exporting GraphsAdding and Removing ContentsSaving Graph for Reuse

Figure Tools

ZoomPanData CursorBasic FittingData Statistics

Plotting Tools

plottoolsFigure PalettefigurepalettePlot BrowserplotbrowserProperty Editorpropertyeditor

Figure Palette: New Subplots

subplot(m,n,p)

Figure Palette: Variables and Plot Catalog

Figure PaletteWorkspace VariablesSelect VariableRight click for plot catalog

Figure Palette: Annotations

LineArrowDouble ArrowText BoxArrow Box. . .

Plot Browser

Displays all plot objectsSelect Plot ObjectChange ObjectPropertiesDeselect Plot ObjectAdd Data

Property Editor

Enable Edit PlotSelect ObjectGo to Property EditorChanging PropertiesMore PropertiesContext Menu

Printing

File > Print PreviewFigure Placement onPage, Paper Size andOrientation etcLine and TextPropertiesColor etc

Exporting

File > Export SetupChange PropertiesExportsaveas

Saving

File > Saveas.fig.m (function)saveas

Publishing Report

Introduction

Formatted report in HTML, PDF, LATEX, MS Word or MS PowerPointSteps Involved

Create a script fileDivide script into ‘code cells’Insert Text Markup for formattingEdit Publish ConfigurationPublish

Publishing Report

Code Cells

Open MATLAB editorEnable Cell modeWrite ScriptDivide Script into Cells by %%Color change and cellseparation lineCan evaluate individual cell

1 %% Create vectors2 theta=linspace(0,10*pi,200);3 r=exp(-theta/10);4 %% Plot using polar plot5 polar(theta,r);

Publishing Report

Document Title and Introduction

Defined in first code cell, starting from1st line%% Document Title% Introduction% IntroductionMust put %% after introductionContents

1 %% This is the Title2 % Introductory text3 % Introductory text4 %%

Publishing Report

Section and Section Titles

New cell in existing section%%New cell that starts newsection %% Section TitleNew section in existing cell%%% Section Title

1 %% New Section2 % introduction3 %%4 % Cell in Existing Section5 %%% New Section in ...

Existing Cell

Publishing Report

Other Text Markup

*bold text *_ italic text_|monospace text|Bulleted List

* Item 1* Item 2

Numbered List# Item 1# Item 2

Hyperlinked Text < www.psiphi.in>

1 %% Other Text Markup2 % *bold text*3 % _italic text_4 % | monospace text |5 %6 % * Item 17 % * Item 28 %9 % # Item 1

10 % # Item 211 %12 % <www.psiphi.in>

Publishing Report

Other Text Markup. . .

Including Image <<IMAGE.JPG>>LATEX Markup% <latex>% LATEX stuff% </latex>TEX Equations $$ eπi + 1 = 0 $$HTML Markup

1 %% More Text Markup2 % <IMAGE.JPG>3 % $$ e^{\pi i}+1=0 $$

Publishing Report

Configuration

Output SettingsOutput File format : HTML, PDF,DOC, PPTOutput File Folder

Figure SettingImage FormatImage Size

Code SettingInclude CodeMax number of lines

publish for changing configurationfrom script

PDFHTMLDoc

FigureCode

Publishing Report

Displaying Results

Command Window o/p:No ;disp display the resultsprintf is useful forformatted o/p

1 %% Displaying Output2 phi=1.618;3 PHI=(1+sqrt(5))/2;4 s=sprintf('phi=%5.3f, ...

PHI=%10.8f',phi,PHI);5 disp(s);6 disp(PHI);7 phi

Publishing Report

Example File

1 %% Document Title2 % Introductory text3 %% Section4 % Section introduction5 %% Other Text Markup6 % *bold text* , _italic text_ , |monospace text|7 % <www.psiphi.in>8 %% More Text Markup9 % The TeX equations can be inserted like:

10 % $$\phi=\frac{1+\sqrt{5}}{2}$$11 %% Displaying Output12 phi=1.618; PHI=(1+sqrt(5))/2;13 s=sprintf('phi=%5.3f, PHI=%10.8f',phi,PHI);14 disp(s); disp(PHI); phi15 %% Plot16 theta=linspace(0,10*pi,200);17 r=exp(-theta/10); polar(theta,r);

Building GUI

Graphical Display forPerforming Tasks InteractivelyEvents→ callback (function,string)Interactive GUI Construction(GUIDE)Programmatic GUIConstruction

Building GUI

guideGetting HelpGUIDE Layout EditorFile > Preference > GUIDE >Show Names in Componentpalette > OKGUI Figure Size > Click andDrag CornerCreating Components

AxesPush ButtonStatic TextPop-up Menu

Building GUI

Creating Simple GUI

simple_ guiAdding Components

AxesThree Push ButtonStatic TextPop-up Menu

Align Pushbuttons > Tools >Align Objects

Building GUI

Creating Simple GUI. . .

Adding Text To ComponentsView > Property Inspector >Push Button: Select PushButton > String > Change itPopup Menu : Select PopupMenu > String >Components in differentlinesStatic Text: Select > String> Change it

Save SimpleGui

Building GUI

Programming Simple GUI

Generating Data to PlotProgramming The PopupMenu: Context Menu, ViewCallbackProgramming The PushButton: Context Menu, ViewCallbackSave and Run GUI

Simulink

Dynamic SystemModeling : Comprehensive block library of sources,sink, linear and nonlinear components, connectorsetcSimulation : Wide choice of Integration MethodAnalysis: Linearization, MATLAB

User Interface

simulink orSimulink Library Browser

- Commonly Used Blocks- Continuous (Derivative,

Integrator, Transfer Function)- Math Operations (Gain, Sum)- Sources (sine wave, step)- Sinks (Scope, To Workspace)- Routing (Mux)

Simulink Model Window- Simulation (Start,

Configuration)- save, printPsiPhiETC (www.psiphi.in) Getting Started with MATLAB January 1, 2012 70 / 74

Example 1: Sine wave and its Integration

Display: sin(t) ,∫ t

t0sin τ dτ

Simulink >File > New > Model >SaveDrag from Library to Model Window

- Source > Sine Wave- Sink > Scope- Continuous > Integrator

- Signal Routing > Mux

Connect blocks- Select 1st > hold Ctrl > Select 2nd- Similar way for branching

Simulation: Configuration, StartScope: Zoom, Export Data

Example: Spring Mass System (Direct Approach)

(f (t)− cx − kx)

Drag Components to model windowTo Rotate: Ctrl+R, To Flip: Ctrl+FGain Parameters by double clickMore input to Sum BlockConnect ComponentsSimout for variables to WorkspaceUnder damped, overdampedSee variables in workspacesim command

Example: Spring Mass System (Transfer Function)

(f (t)− cx − kx)

Drag components to Model WindowConnect ThemDouble click transfer function block forparameter settingDouble click save output to file blockand set file path/nameRun simulationLoad mat file and plot data

Example: Capacitor Charging

V (s) =1s

RCU(s)− 1

RCV (s)

Drag components to Model WindowConnect ComponentsSet parameters for variouscomponentsPlay with Configuration (Solver etc.)SimulationSee results in scope

Getting Started with MATLAB: Slides

spring mass system

model window

desktop tools

interactive computations

context menu

push button

direct approach

sine wave

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