Chapter 1 _ Introduction to Matlab.pptx

Chapter 1 of Introduction to Computing course

1. Chapter 1 Introduction to Matlab

2. To start Matlab on a MS Windows system: Double-click on the Matlab icon. Matlab Desktop Matlab Interactive sessions Starting Matlab

3. Matlab Interactive sessions Starting Matlab Menu names Toolbar Directory Desktop  Desktop Layout  Default

4. Matlab Interactive sessions Starting Matlab In Command window

5. Matlab Interactive sessions Starting Matlab The Current Directory: a file manager window  used to access files. open a file by double-clicking on the file name with the extension .m ( Matlab Editor )

6. Matlab Interactive sessions Starting Matlab Workspace window: Displays the variables created in the Command window. Open Array Editor by double-clicking on a variable name.

7. Matlab Interactive sessions Starting Matlab Command History window: Show all the previous keystrokes entered in the Command window. Used for keeping track what are typed. Can click on a keystroke and drag it to the Command Window or the Editor. Double-click on a keystroke execute it in the Command Window.

8. Matlab Interactive sessions Entering commands and Expressions Enter : Executes the command, retype if there is a mistake. Backspace key, Delete key, the left- / right arrow keys ( ← →) : edit the commands. up- /down-arrow (↑↓) : scroll back/forward through the commands (once to see the previous entry, twice to see the entry before that, and so on)

9. Matlab Interactive sessions Entering commands and Expressions Session (interactive session) The interaction between the user and Matlab Ex: By default, four decimal places are used in the result entry response Can use the command “format” to change the default In Matlab, e represents exponentiation to a power of 10.

10. Matlab Interactive sessions Entering commands and Expressions Variable : a symbol used to contain a value and is assigned the answer by “ans”. “ans” can be used for further calculations. Use variables to write mathematical expression → assign the result to a variable of your own choosing Matlab ignores spaces

11. Matlab Interactive sessions Entering commands and Expressions When we do not specify a variable name for a result, Matlab uses the symbol “ans” as a temporary variable containing the most recent answer.

12. Matlab Interactive sessions Entering commands and Expressions Argument : is the value operated on by the function which is enclosed by the parentheses after the function’s name. There are hundreds of functions available. function’s name argument

13. Symbol Operation Matlab form ^ * / \ + - Exponentiation: a b Multiplication: ab Right division: a/b Left division: a\b Addition: a+b Subtraction: a-b a^b a*b a/b a\b a+b a-b Matlab Interactive sessions Order of Precedence A scalar is a single number. A scalar variable is a variable that contains a single number. Scalar arithmetic operations

14. Precedence Operation First Second Third Fourth Parentheses, evaluated starting with the innermost pair. Exponentiation, evaluated from left to right. Multiplication and division with equal precedence, Evaluated from left to right. Addition and subtraction with equal precedence, evaluated from left to right. Matlab Interactive sessions Order of Precedence Order of precedence Parentheses can be used to alter this order.

15. Matlab Interactive sessions Order of Precedence

16. Matlab Interactive sessions Order of Precedence

17. Matlab Interactive sessions Order of Precedence Practice: Use Matlab to calculate 209.8333 -15.7028 202.4120

18. Matlab Interactive sessions The Assignment Operator

19. Matlab Interactive sessions The Assignment Operator

20. Matlab Interactive sessions The Assignment Operator Example: The volume of a sphere is given by V=4 r 3 /3, where r is the radius. Use Matlab to compute the radius of a sphere having a volume 30 percent greater than that of a sphere of radius 0.3m.

21. Matlab Interactive sessions Variable Names Workspace → names and values of any variables in use in the current work session. Variable names : Begin with a letter. Contain less than 63 characters. Can contain letters, digits, and underscore characters in the rest of the name. Ex: practice, practice_1,...

22. Matlab Interactive sessions Defining variables

23. Matlab Interactive sessions Defining variables

24. Matlab Interactive sessions Rules for variables

25. Matlab Interactive sessions Rules for variables

26. Matlab Interactive sessions Managing the Work Session Command Description clc clear clear var1, var 2 exist (‘name’) quit who whos Clears the Command Window. Removes all variables from memory. Removes the variables var1 and var2 from memory Determines if a file or variable exists having the name “name”. Stop Matlab. Lists the variables currently in memory. Lists the current variables and sizes, and indicates if they have imaginary parts. Commands for managing the work session

27. Matlab Interactive sessions Managing the Work Session Command Description : , ; … Colon; generates an array having regularly spaced elements. Comma; separates elements of an array. Semicolon; suppress screen printing; also denotes a new row in an array. Ellipsis, continues a line. Commands for managing the work session

28. Matlab Interactive sessions Managing the Work Session Use the arrow, tab, and control keys to recall, edit, and reuse functions and variables you typed earlier. ↑ : smart recall, Tab : reduce the amount of typing, Enter : display the value of the variable, or continue editing to create a new executable line. Esc : clear the entire line Ctrl+k : simultaneously to delete (kill) to the end of the line

29. Matlab Interactive sessions Managing the Work Session Command Description ans eps i,j inf NaN pi Temporary variable containing the most recent answer. Specifies the accuracy of floating point precision. The imaginary unit Infinity Indicates an undefined numerical result The number  Special variables and constants

30. Matlab Interactive sessions Managing the Work Session Function: with arguments enclosed in the parentheses. Command/statement: argument is not needed/ or not enclosed in the parentheses. Ex: plot (x); clear; clear x;

31. Matlab Interactive sessions Complex Number Operations addition multiplication subtraction division complex conjugate

32. Matlab Interactive sessions Formatting command

33. Menus and the Toolbar The Desktop Menus In the Command window, some menus are often displayed: File Edit Debug Parallel (new version) Desktop Window Help

34. Menus and the Toolbar The Toolbar The toolbar is below the Menu bar, provides button as shortcut to some of the feature on the menus. New M-file Open File Cut Copy Paste Undo Redo

35. Computing with Matlab Computational capabilities of Matlab Some features used to solve engineering problems Introduction to Matlab

36. Computing with Matlab Overview on Arrays Handling collections of numbers (arrays) is one of computational capabilities of Matlab. A numerical array is an ordered collection of number. The elements of the array must be separated By commas or spaces. Use “length” function to determine how many values are in the array.

37. Example: Computing with Matlab Overview on Arrays

38. Computing with Matlab Polynomial Roots A polynomial in Matlab can be described by an array whose elements are the polynomial’s coefficients, starting with the coefficient of highest power of x. Ex: 4x 3 – 8x 2 + 7x -5 can be represented by

39. Computing with Matlab Built –in Functions

40. Practice Problem 1 Suppose x takes on the values x=1, 1.2, 1.4, ..., 5. Use MATLAB to compute the array y that Results from the function y=7Sin(4x). Use Matlab to determine how many elements are in the array y, and the value of the third element in the array.

41. Practice Problem 2 Use Matlab to determine how many elements are in the array [sin(-pi/2):0.05:Cos(0)]. Use Matlab to: 1. Determine the 10 th element. 2. Create a new array taking the values from the 4 th to 8 th element. 3. Calculate sum of the first three elements of the new array.