A Brief Introduction to MATLAB Evans Library Research Support Workshops

Transcription

1 A Brief Introduction to MATLAB Evans Library Research Support Workshops G.C. Anagnostopoulos 1 1 ICE Laboratory, Florida Institute of Technology November 4 th, 2015

2 The Roadmap 1 Introduction 2 Programming in MATLAB 3 Graphing in MATLAB 4 MATLAB Toolboxes 5 Short MATLAB Demonstration 6 Alternatives to MATLAB 7 References 8 Epilogue Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

3 Introduction Introduction Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

4 Introduction What is MATLAB MAtrix LABoratory MATLAB, not MATHLAB Platform/environment combining computational & graphing capabilities Uses its own interpreted, scripting language Published by MathWorks [MathWorks(2015a)] Over a million of engineering and science users Commercial product; costs $$$ Good news #1: Florida Tech has many licenses Good news #2: affordable student version Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

5 Introduction Origins Cleve Moler author of LINPACK and EISPACK invented MATLAB in the 70 s at University of New Mexico Co-founded MathWorks in 1984 with John Little and Steve Bangert. Figure: Cleve Moler Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

6 Introduction Advantages Excellent rapid prototyping tool Allows interfacing with other languages Ability to build standalone applications Extended via numerous toolboxes Supports GPU and cluster computing Extensive online support via Mathworks website MATLAB Central File Exchange [MathWorks(2015b)]: a user community Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

7 Programming in MATLAB Programming in MATLAB Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

8 Programming in MATLAB MATLAB GUI Figure: MATLAB GUI screenshot Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

9 Programming in MATLAB MATLAB Editor Figure: MATLAB Editor screenshot Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

10 Programming in MATLAB Data Types MATLAB supports a variety of data types. Numeric Integers, Floating Points, Complex Numbers, Infinity, NaN, etc. Strings Categorical Function handles etc. Most of them can be thought of as matrices (even scalars!) Arrays Cell Arrays Matrices Structures & Classes etc. Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

11 Programming in MATLAB Main Programming Features Control Flow if, elseif, else, switch, case while, for try, catch Operators Arithmetic: +,,, /,, etc. Relational: <, >, <=, >=, ==, = Logical: &,,, xor, etc. Set Bit-wise Functions I/O operations (Data Import/Export) GUI construction Debugging & Profiling Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

12 MATLAB Functions Programming in MATLAB Functions are stored in their own *.m files Can have multiple input & output arguments Example function: 1 % MYFACTORIAL 2 % Returns the factorial of a positive integer. 3 % Stored in myfactorial.m 4 function value = myfactorial(n) 5 6 if n == 0 7 value = 1; 8 else 9 value = n * myfactorial(n-1); 10 end return Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

13 Programming in MATLAB GUI Example Figure: GUI example Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

14 Programming in MATLAB Object-Oriented Programming Supported to some extend e.g., Inheritance, but not polymorphism Has its own idiosyncrasies Ever-evolving Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

15 Graphing in MATLAB Graphing in MATLAB Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

16 Graphing in MATLAB Visualization in MATLAB 2D and 3D plots Images Formatting & Annotation Exporting graphics Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

17 Examples of Plots I Graphing in MATLAB Figure: Combined Line & Stem Plot Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

18 Examples of Plots II Graphing in MATLAB Figure: Overlay 2D Bar Graphs Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

19 Examples of Plots III Graphing in MATLAB Figure: Combine Contour Plot and Quiver Plot Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

20 Examples of Plots IV Graphing in MATLAB Figure: Color 3D Bar Graph Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

21 Examples of Plots V Graphing in MATLAB Figure: Polar Plot Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

22 Examples of Plots VI Graphing in MATLAB Figure: Stream Line Plot of Vector Data Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

23 Examples of Plots VII Graphing in MATLAB Figure: Surface Plot Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

24 Examples of Plots VIII Graphing in MATLAB Figure: Image Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

25 Examples of Plots IX Graphing in MATLAB Figure: 3-D Contour Slice Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

26 Examples of Plots X Graphing in MATLAB Figure: Isocaps Plot Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

27 Examples of Plots XI Graphing in MATLAB Note: All previous images were sourced from MathWorks website. Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

28 MATLAB Toolboxes MATLAB Toolboxes Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

29 MATLAB Toolboxes Toolboxes I MATLAB s core functionality is extended via toolboxes in the following areas: Math, Statistics, and Optimization Symbolic Math, PDEs, Statistics, Optimization, etc. Control Systems System Identification, Robust Control, Aerospace, Robotics Systems, etc. Signal Processing and Communications Signal Processing, Communications, Wavelet, Antenna, etc. Image Processing and Computer Vision Image Processing, Image Acquisition, Computer Vision, Mapping, etc. Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

30 MATLAB Toolboxes Toolboxes II Test and Measurement Data Acquisition, Instrument Control, etc. Computational Finance Financial, Econometrics, Datafeed, Trading, etc. Computational Biology Event-Based Modeling Physical Modeling Real-Time Simulation and Testing Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

31 Short MATLAB Demonstration Short MATLAB Demonstration Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

32 Demo transcript Short MATLAB Demonstration Let us fire-up MATLAB now... Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

33 Demo transcript I Short MATLAB Demonstration MATLAB code 1 %% Getting started 2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 3 4 % Lines starting with a "%" character signify comments and MATLAB 5 % ignores them 6 7 % Prints out MATLAB version number 8 ver 9 10 % See how fast your computer is 11 bench % Clear command window 14 clc % Help! 17 help 18 Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

34 Demo transcript II Short MATLAB Demonstration 19 % Get "man-page" quality help regarding a specific command... (here, "clc") 20 help clc % Get more information on a command (here, "clc") through the... help browser 23 doc clc % look for information on a topic 26 lookfor 'clear command window' % See what variables are currently available in the workspace 29 who 30 a = 1 % prints out variable value 31 a = 2; % ';' suppresses the printing out of variable value 32 who % Clear all variables from workspace 35 clear 36 who 37 Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

35 Demo transcript III Short MATLAB Demonstration 38 % Have some fun with MATLAB Easter eggs such as this one 39 why %% Some simple code snippets 43 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % About functions 46 help myfactorial % prints out the first comment lines in... myfactorial.m 47 type myfactorial % dumps the contents of myfactorial.m onto the... screen 48 edit myfactorial % bring myfactorial.m into the editor 49 N = randi(5); % call built-in function randi() to get a random... integer 50 myfactorial(n) % N! = 1*2*...*N % For-loops vs. vectorized operations 53 N = ; 54 x = 1 : N; % x == [ N] 55 tstart = tic; % tic is a built in function Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

36 Demo transcript IV Short MATLAB Demonstration 56 for i = 1 : N 57 x(i) = x(i)ˆ2; % call to built-in function randn() 58 end % i-loop 59 telapsed = toc(tstart) % elapsed time since tic call in seconds x = 1 : N; 62 tstart2 = tic; 63 x = x.ˆ 2; % avoiding for-loops via use of vectorized operations 64 telapsed2 = toc(tstart2) % is faster %% Sample computations 68 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Linear algebra computations 71 b = [ 3 3 ]' % transposition of a row vector gives a column vector 72 A = [ 2 1; 1 2] 73 det(a) % determinant 74 inv(a) % inverse matrix 75 x = A\b % solve A * x = b equation 76 Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

37 Demo transcript V Short MATLAB Demonstration 77 % Computing roots of polynomials 78 c = [1-2 1]; 79 roots(c) % roots of the polynomial c(1)*xˆ2 + c(2)*x + c(3) % Numerically integrating a function 82 fun exp(-0.5 * x.ˆ2); % a Gaussian function 83 integral(fun,-inf,inf) % == sqrt(2 * pi) %% Some plots 87 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % 2D plot 90 % Inspired by 91 % 2001-what-matlab-easter-eggs-do-you-know 92 h = figure; % get figure handle 93 set(h, 'color', 'white') % set figure background to white 94 x = -2.0 :.001 : 2.0; 95 y = (real(sqrt(cos(x))).* cos(200*x) + sqrt(abs(x)) -0.7 ) % use... to continue on next line 97.* (4 - x.*x).ˆ 0.01; Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

38 Demo transcript VI Short MATLAB Demonstration 98 plot(x, y, 'red'); % plot curve 99 xlabel('x') % label the x axis as 'x' 100 ylabel('y') % label the y axis as 'y' 101 title('a heart') % add a figure title 102 axis equal % force same scaling to both axes % 2D animation 105 x = 0 : 10 : 360; % angle measured in degrees 106 y = sind(x); % sind: sine function accepting arguments in degrees 107 phi=0; 108 disp('press Ctrl-C to stop animation') % display message on screen 109 while 1 % infinite loop to animate the sine curve 110 phi = phi + 1; 111 ya = y * sind(phi); % change amplitude of sinusoid 112 plot(x, ya); % plot the curve 113 axis([0, 360, -1.1, 1.1]); % set axix limits 114 pause(0.005); % slow down animation 115 end % 3D interpolated surface plot (can be rotated) 118 logo Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

39 Demo transcript VII Short MATLAB Demonstration %% Some pre-built GUIs 122 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Example of a GUI 125 xpbombs % mine sweeper! % Another GUI example 128 lorenz % orbits around the Lorenz chaotic attractor % quit MATLAB 131 quit Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

40 Alternatives to MATLAB Alternatives to MATLAB Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

41 MATLAB Alternatives Alternatives to MATLAB 1 Free, open-source, direct alternatives GNU Octave [Octave(2015)] SciLab [Scilab(2015)] FreeMat [FreeMat(2015)] 2 Free, open-source, somewhat similar alternatives R Project [R(2015)] SciPy [SciPy(2015)] SageMath [Sage(2015)] Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

42 Alternatives to MATLAB Regarding GNU Octave Core syntax and functionalities identical to MATLAB s Used to be command-line-only, now has GUI Major Pros/Cons: free/slower than MATLAB Figure: GNU Octave GUI screenshot Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

43 References References Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

44 References References I FreeMat. Freemat sourceforge website, URL MathWorks. Mathworks official website, 2015a. URL MathWorks. Matlab central file exchange, 2015b. URL GNU Octave. Gnu octave official website, URL R. R project official website, URL Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

45 References References II Sage. Sagemath official website, URL Scilab. Scilab official website, URL SciPy. Scipy official website, URL Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

46 Epilogue Epilogue Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

47 Epilogue Q&A I will be happy to entertain a few quick questions... Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48

48 Epilogue Thanks! Thank you for having me in this workshop series! Anagnostopoulos A Brief Introduction to MATLAB November 4 th, / 48