1 / 27

Getting started with Matlab

Getting started with Matlab. Numerical Methods Appendix B http://www.mathworks.com/access/helpdesk/help/techdoc/learn_matlab/learn_matlab.html. What Is MATLAB?. Math and computation Algorithm development Data acquisition Modeling, simulation, and prototyping

kiger
Download Presentation

Getting started with Matlab

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Getting started with Matlab Numerical Methods Appendix B http://www.mathworks.com/access/helpdesk/help/techdoc/learn_matlab/learn_matlab.html

  2. What Is MATLAB? • Math and computation • Algorithm development • Data acquisition • Modeling, simulation, and prototyping • Data analysis, exploration, and visualization • Scientific and engineering graphics • Application development, including graphical user interface building

  3. The MATLAB System • Development Environment. • The MATLAB Mathematical Function Library. • The MATLAB Language. • a high-level matrix/array language • Graphics. • The MATLAB External Interfaces (API).

  4. MATLAB Online Help • Desktop Tools and Development Environment • Mathematics • Programming • Graphics • 3-D Visualization • Creating Graphical User Interfaces • External Interfaces/API

  5. Matrices and Arrays • To enter Dürer's matrix, simply type in the Command Window • >>A = [16 3 2 13; 5 10 11 8; 9 6 7 12; 4 15 14 1] • A = • 16 3 2 13 • 5 10 11 8 • 9 6 7 12 • 4 15 14 1

  6. sum, transpose, and diag • sums of the columns of A • >>sum(A) • ans = 34 34 34 34 • >>sum(A')' • ans = • 34 • 34 • 34 • 34 • sum(diag(A)) • ans = 34 The transpose operation is denoted by an apostrophe or single quote, '.

  7. Subscripts • >>A(1,4) + A(2,4) + A(3,4) + A(4,4) • ans = 34 • >>X = A; • >>X(4,5) = 17 • X = • 16 3 2 13 0 • 5 10 11 8 0 • 9 6 7 12 0 • 4 15 14 1 17

  8. The Colon Operator • >> 1:10 • ans = 1 2 3 4 5 6 7 8 9 10 • >> 100:-7:50 • ans = 100 93 86 79 72 65 58 51 • >> 0:pi/4:pi • ans = 0 0.7854 1.5708 2.3562 3.1416 • In subscript • >> A(1,1:4) • ans = 16 3 2 13

  9. The magic Function • >> B = magic(4) • B = • 16 2 3 13 • 5 11 10 8 • 9 7 6 12 • 4 14 15 1 • To make this B into Dürer's A, swap the two middle columns: • A = B(:,[1 3 2 4])

  10. Expressions • Variables • num_students = 25 • Numbers • 3 -99 0.0001 9.6397238 1.60210e-20 6.02252e23 1i -3.14159j 3e5i • Operators • +-*/^ • \ Left division • Functions • help elfun • help specfun • help elmat

  11. Working with Matrices

  12. Generating Matrices • zeros All zeros • ones All ones • rand Uniformly distributed random elements • randn Normally distributed random elements

  13. ones(n,m) • >> ones(3,4) • ans = • 1 1 1 1 • 1 1 1 1 • 1 1 1 1

  14. zeros(n,m) • >> zeros(3,4) • ans = • 0 0 0 0 • 0 0 0 0 • 0 0 0 0

  15. rand(n,m) • >> rand(3,4) • ans = • 0.9501 0.4860 0.4565 0.4447 • 0.2311 0.8913 0.0185 0.6154 • 0.6068 0.7621 0.8214 0.7919

  16. randn(3,4) • >> randn(3,4) • ans = • -0.4326 0.2877 1.1892 0.1746 • -1.6656 -1.1465 -0.0376 -0.1867 • 0.1253 1.1909 0.3273 0.7258

  17. Load and Save .mat • >> A = [1 2 3] • >> B = [4 5 6] • >> save mydata.mat • >> clear • >> load mydata.mat

  18. >> eye(3) ans = 1 0 0 0 1 0 0 0 1 >> eye(size(A)) ans = 1 0 0 0 0 1 0 0 0 0 1 0 eye(n), eye(size(A))

  19. Load and save ASCII file • >> a = magic(4); b = ones(2, 4) * -5.7; c = [8 6 4 2]; • >> save -ascii mydata.dat • >> clear • >> load mydata.dat • >> mydata • mydata = • 16.0000 2.0000 3.0000 13.0000 • 5.0000 11.0000 10.0000 8.0000 • 9.0000 7.0000 6.0000 12.0000 • 4.0000 14.0000 15.0000 1.0000 • -5.7000 -5.7000 -5.7000 -5.7000 • -5.7000 -5.7000 -5.7000 -5.7000 • 8.0000 6.0000 4.0000 2.0000

  20. Building Tables • >> n = (0:9)'; • pows = [n n.^2 2.^n] • pows = • 0 0 1 • 1 1 2 • 2 4 4 • 3 9 8 • 4 16 16 • 5 25 32 • 6 36 64 • 7 49 128 • 8 64 256 • 9 81 512 MATLAB uses a dot, or decimal point, as part of the notation for multiplicative array operations.

  21. Multivariate Data • >>D = [ • 72 134 3.2 • 81 201 3.5 • 69 156 7.1 • 82 148 2.4 • 75 170 1.2 ] • to obtain the mean and standard deviation of each column, use • >>mu = mean(D), sigma = std(D) • mu = 75.8 161.8 3.48 • sigma = 5.6303 25.499 2.2107 • >>help datafun • >>help stats

  22. Matlab Graphics

  23. plot(x,y) • t=[0:5:100] • y=t.^0.34-log10(t)+1./t • plot(t,y) • title(‘Plot of y versus t’) • grid

  24. 3D graphics • [x,y]=meshgrid(-4.0:0.2:4.0,-4.0:0.2:4.0); • z=(-20*x.^2+x)+(-15*y.^2+5.*y); • surfl(x,y,z); • axis([-4 4 -4 4 -800 0]) • xlabel('x-axis'); • ylabel('y-axis'); • zlabel('z-axis');

  25. Try yourself, and have fun!

More Related