1. Lecture 20: Choosing the Right Tool for the Job

2. What is MATLAB? MATLAB is one of a number of commercially available, sophisticated mathematical computation tools. Others include Maple Mathematica MathCad

3. MATLAB Excels at Numerical calculations Especially involving matrices Graphics MATLAB stands for Matrix Laboratory

4. Why MATLAB Easy to use Versatile Built in programming language Not a general purpose language like C/C++ or Java MATLAB was written in C Electrical EngineeringBiomedical Engineering Fluid Dynamics

5. Getting Started Type in matlab& at the shell prompt in your terminal. MATLAB opens to a default window configuration

6. MATLAB uses a standard windows menu bar To exit MATLAB use the close icon or from the menu: File->Exit MATLAB

7. Command Window Enter commands at the prompt Current Directory MATLAB Windows Command History Workspace Window

8. You can use the command window much like you’d use a calculator The standard order of operation rules apply Command Window

9. Workspace Window

10. Scalar Vector 2-D Matrix

11. Document Window If you double click on any variable in the workspace window MATLAB launches a document window containing the array editor You can edit variables in the array editor

12. Document Window

13. Figure Window When Figures are created a new window opens It’s extremely easy to create graphs in MATLAB The semicolon suppresses the output from each command

14. Editing Window This window allows you to type and save a series of commands without executing them There are several ways to open an editing window –From the file menu –With the new file icon

15. Open an editing window from the file menu or with the new file icon

16. Save and Run Write your code in the editing window, then run it using the Save and Run icon

17. Solving Problems with MATLAB

18. Naming Variables All names must start with a letter They may contain letters, numbers and the underscore ( _ ) Names are case sensitive There are certain keywords you can’t use (iskeyword)

19. The Basic Data Type in MATLAB: Matrices Group of numbers arranged into rows and columns Single Value (Scalar) Matrix with one row and one column Vector (One dimensional matrix) One row or one column Matrix (Two dimensional)

20. Array Operations Using MATLAB as a glorified calculator is OK, but its real strength is in matrix manipulations

21. To create a row vector, enclose a list of values in brackets

22. You may use either a space or a comma as a “delimiter” in a row vector

23. Use a semicolon as a delimiter to create a new row

25. Shortcuts While a complicated matrix might have to be entered by hand, evenly spaced matrices can be entered much more readily. The command b= 1:5 or the command b = [1:5] both return a row matrix

26. The default increment is 1, but if you want to use a different increment put it between the first and final values

27. To calculate spacing between elements use linspace initial value in the array final value in the array number of elements in the array

28. Calculations between scalars and arrays

29. Calculations between arrays: addition and subtraction Addition between arrays is performed on corresponding elements Subtraction between arrays is performed on corresponding elements

30. MATLAB interprets * to mean matrix multiplication. The arrays a and b are not the correct size for matrix multiplication in this example Multiplication between arrays is performed on corresponding elements if the.* operator is used

31. Array Operations Array multiplication.* Array division./ Array exponentiation.^ In each case the size of the arrays must match

32. Transpose The transpose operator changes rows to columns or vice versa.

33. The transpose operator makes it easy to create tables

34. table =[degrees;radians]’ would have given the same result

35. The transpose operator works on both one dimensional and two dimensional arrays

36. Saving Your Work If you save a MATLAB session, all that is saved are the values of the variables you have named

37. Save either by using the file menu or... Save with a command in the command window MATLAB automatically saves to a.mat file

38. Script M-files If you want to save your work, you need to create an M-file File->New->M-file Type your commands in the edit window that opens The file is saved into the current directory It runs in the command window

39. Comments The % sign identifies comments You need one on each line