Introduction to MATLAB. Todd Atkins

Transcription

1 Introduction to MATLAB Todd Atkins 1

2 MATLAB The Language for Technical Computing Key Features High-level language of technical computing Development environment for engineers, scientists Interactive tools for design, problem solving Mathematical function libraries Graphics and data visualization tools Custom GUIs External Interfaces: C, C++, Fortran, Java, COM, Excel,.NET 2

3 Technical Computing Workflow Access Explore and Discover Share Automate 3

4 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB 7

5 MATLAB Desktop 8

6 Workspace Browser 9

7 Getting Help doc Start -> Help -> Support -> Product Documentation help Search the web 11

8 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB 12

9 Basics: Data and Variables Class Size Value 14

10 Basics: Data and Variables Class Size Value m*n m*n* *z 15

11 Basics: Data and Variables Class Size Value 16

12 Basics: Data and Variables Class Size Value Name ( variable ) foo 17

13 Basics: Manipulating Data Creation Extraction (subset) Union (merge) Deletion 19

14 Basics: Manipulating Data Creation Extraction (subset) Union (merge) Deletion : rand zeros ones diag magic ; end linspace logspace 20

15 Basics: Manipulating Data Creation Extraction (subset) Union (merge) Deletion Subscript Linear Logical () sub2ind ind2sub 21

16 Basics: Manipulating Data Creation Extraction (subset) Union (merge) Deletion Subscript <name>(row, col) <name>(row, col,, z) Indices may themselves be arrays. 22

17 Basics: Manipulating Data Creation Extraction (subset) Union (merge) Deletion Linear <name>(location) Where <location> is: row+(col-1)*num_rows Location may be an array. 23

18 Basics: Manipulating Data Creation Extraction (subset) Union (merge) Deletion Logical <name>(<logical_array>) Where the dimensions of <name> and <logical_array> are the same and <logical_array> is of type logical. 24

19 Basics: Manipulating Data Creation Extraction (subset) Union (merge) Deletion [] repmat strvcat Expansion cat horzcat vertcat 25

20 Basics: Manipulating Data Creation Extraction (subset) Union (merge) Deletion clear clearvars Assign to empty 26

21 Basics: Manipulating Data () versus [] Indexing Order of operations Argument list Matrix/Vector creation Concatenation Multiple outputs 27

22 Basics: Manipulating Data : 1:5 0:5:25 25:-3:2 25:5:0 0:.5:4 28

23 Basics: Manipulating Data end a(1:end) b(end, end) 29

24 Basics: Math Matrix operations >> a = [1 2; 3 4] >> b = [5 6; 7 8] >> c = a*b Element operations (dot) >> a = [1 2; 3 4] >> b = [5 6; 7 8] >> c = a.*b >> d = a.^3 + b^2 Others ^ - Power \ - Left divide ' - Transpose 31

25 Basics: Math Scalar expansion >> a = [1 2; 3 4] >> a+[1 2] >> a+1 What happens? 32

26 Demo Compute y = sin(2t) + cos(t) where t is from 1 to 10 seconds. MATLAB Functions sin cos plot 33

27 MATLAB Functions 34

28 Calling Functions Function calling syntax: [out1, out2,..., outn] = functionname(in1, in2,..., inn) Aside - Command syntax: functionname string1 string2 string3 stringn Revisit the Help. 35

29 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB 36

30 Consider one Global Warming! 38

31 Is the temperature rising? Climatic Research Unit School of Environmental Sciences at University of East Anglia, Norwich, UK Importing data Data set for land/sea combined temperature anomalies on a 5 by 5 grid-box basis (HadCRUT3.mat) Visualizing data Different methods to plot and observe data Analyzing data Computational analysis to check if temperature is rising? 39

32 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB 40

33 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB Import/Extract/Export Visualize Analyze 41

34 Technical Computing Workflow Access Explore and Discover Share Automate 42

35 Technical Computing Workflow: Access Access Explore and Discover Share Files File->Import Data uiimport importdata csvread xlsread aviread wavread fread fscanf load/save doc fileformats Software COM/.NET Java C/C++ SOAP/WSDL Database OPC ftp urlread Hardware Data Acquisition Instrument Control TCP/IP Serial Image Acquisition Automate 43

36 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB Writing MATLAB programs Programming logic control 47

37 Writing MATLAB Programs Using MATLAB Editor Executing MATLAB script Reusing MATLAB programs 48

38 MATLAB Program Files Why? Automating Editing/Debugging Deploying as applications MATLAB Scripts MATLAB Functions 49

39 Basics of a MATLAB Program File function [y1, y2] = functionname(x1,x2, ) >> help fact Compute a factorial value. H1 line FACT(N) returns the factorial of N, Help text usually denoted by N! >> fact(3) ans = 6 50

40 Exercise Write Function definition for istriangle.m Given 3 lengths, Is (sum of 2 sides)> 3 rd side? Is it Scalene, Isosceles or Equilateral? What is the area of triangle, if exists? 51

41 Types of Functions Primary MATLAB-file Functions 52

42 Types of Functions Primary MATLAB-file Functions Subfunctions 53

43 Types of Functions Primary MATLAB-file Functions Subfunctions Nested Functions 54

44 Types of Functions Primary MATLAB-file Functions Subfunctions Nested Functions Anonymous Functions Overloaded Functions Private Functions 55

45 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB Import/Extract/Export Visualize Analyze 56

46 Technical Computing Workflow Access Explore and Discover Share Automate 57

47 Visualization Tools 2-d plots 3-d plots 58

48 Plotting Tools >> x = [0:0.2:20]; >> y = sin(x).sqrt(x+1); >> y(2,:) = sin(x/2).sqrt(x+1); >> y(3,:) = sin(x/3).sqrt(x+1); >> plot(x,y); 59

49 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB Import/Extract/Export Visualize Analyze 61

50 Basic Operations Processing and Analyzing Data Data Analysis functions in MATLAB Statistics cov, max, mean, median, std Filtering and Convolution conv, deconv, filter, filter2 Interpolation and Regression interp1, interpn, mldivide, polyfit, polyval Fourier Transforms fft, fftn, fftshift, ifft, umwrap Derivatives and Integrals del2, diff, gradient, polyint, trapz 62

51 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB Writing MATLAB programs Programming logic control 65

52 Outline MATLAB Desktop Computing in MATLAB Problem Solving with MATLAB Working with data in MATLAB Programming in MATLAB Writing MATLAB programs Programming logic control 66

53 Program Control Statements Conditional Control if/elseif/if, switch/case Loop Control while, for, break Error Control try, catch 67

54 Conditional Control Statements if, elseif and else switch, case and otherwise 68

55 Loop Control Statements while (Conditional Loop) for (Iterative Loop) continue, break 69

56 Technical Computing Workflow Access Explore and Discover Share Automate 72

57 3-D Visualization Features Surface and Mesh plots peaks, surf, mesh, meshgrid colorbar, colormap, shading View Control campos, view, daspect, rotate3d Lighting and Transparency camlight, diffuse, alpha Volume Visualization curl, isosurface, slice 74

58 Object-Oriented Programming 75

59 External Interfaces Shared libraries (.dll,.so,.dylib) C, Fortran interface C, Fortran MEX-files (.mex) Sun Java classes COM/.NET support Web services Serial Port I/O 76

60 More on MATLAB MATLAB Tutorials Demos and Webinars Documentation MATLAB Central (User Community) 77

61 Training Tutorials 78

62 Training Tutorials 79

63 Training Tutorials MATLAB Simulink Control Systems Signal Processing 80

64 Demos 82

65 Demos 83

66 Summary MATLAB is a high level-language for technical computing Interactive tool with mathematical and graphical functions MATLAB provides features to access, compute, analyze and visualize data MATLAB also provides capabilities to interface with external languages 85