1. Matlab Programming for Engineers
Introduction to Matlab Matlab Basics Branching Statements Loops User Defined Functions Additional Data Types Input/Output Functions Simulink Toolbox Important Toolboxes (if time is available)
Dr. Nidal Farhat

2. Relational Operators (==, ~=, >, < , >=, <=)
OBJECTIVES
The Logical Data Type
Relational Operators (==, ~=, >, < , >=, <=)
Logic Operators (&, &&, |, ||, xor, ~)
Logical Functions (ischar, isempty, ….)
Branches
(if-else) Statement
switch Statement
try-catch Statement
Additional Plotting Features

3. THE LOGICAL DATA TYPE (true, false)

4. RELATIONAL OPERATORS (==, ~=, >, < , >=, <=)
Some relational operations and their results

5. RELATIONAL OPERATORS (==, ~=, >, < , >=, <=)
Be careful because of roundoff errors
Compare array by a value
Compare array by another one (of the same size)

6. LOGIC OPERATORS Operator Operation &
Logical AND (scalar/array, both sides evaluation)
&&
Logical AND (scalar, left then right side evaluation) |
Logical inclusive OR (scalar/array both sides evaluation) ||
Logical inclusive OR (scalar, left then right side evaluation)
xor
Logical exclusive OR ~
Logical NOT

7. LOGIC OPERATORS
EXAMPLE

8. LOGICAL FUNCTIONS

9. QUIZ!

10. Branches:
a) if Statement

11. BRANCHES (if-STATEMENT)
Optional

12. BRANCHES (if-STATEMENT)
Example:
Write a program that determine whether a quadratic equation:
has real (identical/different) or complex roots. (Use input command for entering the coefficients (a,b,c) and disp commands to display the output).
Write a program that calculates the roots in each case. (Use input command for entering the coefficients of the equation and disp commands to display the output).
Test the program on the following equations:

13. BRANCHES (if-STATEMENT)
Example: evaluating a Function of Two Variables
Test it using the following (x,y) values:

14. BRANCHES (if-STATEMENT)
Nested if-Statements
It is preferable to use if-else-end statement whenever is possible

15. Branches:
b) switch Statement

16. BRANCHES (switch-STATEMENT)
The switch statement syntax is a means of conditionally executing code. In particular, switch executes one set of statements selected from an arbitrary number of alternatives.
The switch_expr and case_expr may be a scalar or a string
Optional

17. BRANCHES (switch-STATEMENT)
Remarks:
The case expression could be more than one enclosed by {}
At most one code block can be executed. If the switch_exp matches more than case_exp the first one is executed.

18. BRANCHES (switch-STATEMENT)
Example:

19. BRANCHES (switch-STATEMENT)
Example:
Example

20. BRANCHES (switch-STATEMENT)
Example

21. b) try/catch Statement
Branches:
b) try/catch Statement

22. BRANCHES (try/catch)
The try/catch statement is designed to trap errors.
In MATLAB when an error is encountered while running the program the program execution is aborted.
Use try/catch statement to run a part of the program susceptible to produce error when executed. MATLAB will try to execute this part. If an error is produced, then instead of aborting, it executes the part of the program found in the catch statement.
If no error is produced in the try block, the catch block will not be executed.
 The programmer can handle errors in the program without causing the program to stop.

23. BRANCHES (try/catch)

24. BRANCHES (try/catch)
Example

25. fprintf command
fprintf(format,data)

26. Additional plotting features
Example f(x) = sin(x), from -2π to 2π
Then restrict the axes to the region 0 ≤ x ≤ π, and 0 ≤ y ≤ 1

27. Additional plotting features
Plotting Multiple Plots on the Same Axes OR

28. Additional plotting features
Creating Multiple Figures

29. Additional plotting features
Subplots
Subplot(m,n,p) ≡ creates mxn subplots in the current figure (array of subplots), m rows and n columns. p is the current subplot.
p=1
p=2
p=3
p=4
p=[5 6]

30. Additional plotting features
Enhanced Control of Plotted Lines
plot(x,y,'PropertyName',value,…)

31. Additional plotting features
Enhanced Control of Plotted Lines
Example,

32. Additional plotting features
Enhanced Control of Text Strings

33. Additional plotting features
Enhanced Control of Text Strings

34. Additional plotting features
Enhanced Control of Text Strings
Examples:

35. Additional plotting features
Polar Plots
polar(theta,r)
Example,

36. Additional plotting features
Polar Plots
polar(theta,r)
Solution: