Introduction To MATLAB

Introduction to MATLABArturo Donate

IntroductionWhat is MATLAB?ToolboxesEnvironmentComparisonMATLAB BasicsConclusionProgramming

What is MATLAB?Matrix laboratoryprogramming environmenthigh-performance languageWindows, OSX, Linux/UNIXMatrix/Vector computationslinear equations, eigenvectors, etc.LINPACK, EISPACK, LAPACK, BLAS, etc.

What is MATLAB?Uses:math & computationalgorithm developmentmodeling and simulationdata analysis and visualizationapplication development

What is MATLAB?Toolboxesimage processingfiltering, transforms, analysis, enhancementstatisticslinear models, probability dist., HMMsoptimizationmax/minimization, least squares, line fitting

What is MATLAB?Toolboxesfixed-pointfixed-point data type & arithmeticothers:symbolic mathsignal processingvirtual reality

Environment

Environment

Basic Console Commandshelpevallsdispwho, whoswhat, typeclear, packlookfor, whichload, saveexit, quit

Basic Math CommandsOperationsConstantsmean, median, modepi 3.14159.sum, absi, j sqrt(-1)sin, sinh, asin, etc.realmin, realmaxsqrt, log, expInf, NaNfloor, ceil, roundhist, plot

Vectors and MatricesCreatingM ones(10,10)zeros, rand, randn,eye, magic)M [1 2 3; 4 5 6; 7 89]M(1,1) 23M [eye(6) rand(6)]AccessingM(x, y)M(x, :), M(x, i:j)DeletingM []

Vectors and MatricesOperations -*/ ‘eigany, allsvddiagtracerankprod

Vectors and MatricesSample expressions:A B*Cdeterm det(C)num abs(3 4i)index find(C 0)vector sin(1:50)x isprime(y)B [A’ C’]num numel(x)B(:,2) [][x y] size(C)

Vectors and MatricesColon notation1 : 50A(1:3, 2)1 : 2 : 50A(2:4, :)A(:, 2)sin(0 : pi/20 : 2*pi)

Graphics2D Example: plot( sin( 0 : pi/20 : 2*pi ) )

Graphics3D example - plot 3D point cloud

Graphics

ProgrammingFunctionsfunction [X Y] func name(arg1,arg2)func name.mprimary vs subfunctionsnested functiondeclaration/definitionprivate functionsfunction overloading(int vs double)global variablespre-allocationvectorization

Programmingscript vs functionif, elseif, elsefor, whileswitch, casecontinue, breakreturn

ProgrammingRelations aa ba ba aa ba ba&b

ProgrammingData StructuresMatrixbasic data typeCellmulti-dimensionalmatricesStringcharacter arrayStructuretype with variousfields

Simple Example: SVDCreate a function that:takes a matrix as inputmake sure the matrix is squarecomputes the SVD decompositionreturns the first singular value“answer my func(matrix)”

Simple Example: SortCreate a function that:takes a list as inputsorts the listreturns a list with sorted values“answer my func(matrix)”

Image ProcessingToolbox used for image processing, computervision, and signal processing tasksimage transformationregistrationfilteringimage analysis/enhancement/de-blurringsegmentationetc.

Image ProcessingNoise reduction examplesalt & pepper noisemean, median filterfilter2( fspecial(‘average’, 3), image) / 255medfilt2(image, [3 3])

Image ProcessingColor segmentation examplecform makecform(‘srgb2lab’)lab img applycform(image, cform)ab double(lab img(:,:,2:3))nrows size(ab, 1)ncols size(ab, 2)ab reshape(ab, nrows*ncols, 2)

Image Processing[cluster idx, cluster center] kmeans(ab, 3,‘distance’, ‘sqEuclidean’, ‘Replicates’, 3);label reshape(cluster idx, nrows, ncols, 1);

Image ProcessingTexture segmentation exampleE entropyfilt(I);Eim mat2gray(E);BW1 im2bw(Eim, 0.8);BWao bwareaopen(BW1, 2000);nhood true(9);

Image ProcessingcloseBWao imclose(BWao, nhood);roughmask imfill(closeBWao, ‘holes’);I2 I; I3 I;I2(roughmask) 0;I3( roughmask) 0;

MATLAB ClonesPackages: Scilab, Octave, RlabSimilar:matrix is basic data typecomplex number supportbuilt-in mathematical functionspowerful libraryuser-defined functions

MATLAB ClonesScilabwww.scilab.orgbest support & docsgood -likemost compatibleRlabrlab.sourceforge.netattempts to improvesyntax/semanticsleast compatible

Conclusionsinteractive programming environmenthigh performance languagealgorithm designmodeling & simulationanalysis & visualizationlinear algebratoolboxes

ReferencesMATLAB:www.mathworks.comMATLAB LAB Comparison:www.dspguru.com/sw/opendsp/mathclo2.htm

What is MATLAB? Uses: math & computation algorithm development modeling and simulation data analysis and visualization application development