1. Introduction to MATLAB 7 for Engineers
بسم الله الرحمن الرحيم
King Abdulaziz University
College of Engineering
Dept of Electrical & Computer Engineering
Structured Computer Programming EE 201
Introduction to MATLAB 7
for Engineers

2. Course Syllabus Instructor: Eng. Ghassan R. Alnwaimi
Instructor: Eng. Ghassan R. Alnwaimi
Web Site:
Office Room: 317B, Tel Ext
Office Hours: Saturday to Wednesday : p.m.
Textbook:
William J. Palm III, Introduction to MatLab 7 for Engineers, McGraw-Hill International Edition, 2005
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

3. The Default MATLAB Desktop
Chapter 1
The Default MATLAB Desktop
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

4. Entering Commands & Expressions
MATLAB retains your previous keystrokes.
Use the up-arrow key to scroll back through the commands.
Press the key once to see the previous entry, and so on.
Use the down-arrow key to scroll forward. Edit a line using the left-and right-arrow keys the Back space key, and the Delete key.
Press the Enter key to execute the command.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

5. Example: >> 8/10 ans= 0.8000 >> 5*ans 4 >> r=8/10
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

6. Scalar Arithmetic Operations
Symbol Operation MATLAB form
^ exponentiation: a^b
* multiplication: ab a*b
/ right division: a/b a/b
\ left division: b/a a\b
addition: a + b a + b
subtraction: a –b a -b
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

7. Order of Precedence
First  Parentheses, evaluated starting with the innermost pair.
Second  Exponentiation, evaluated from left to right.
Third  Multiplication and division with equal precedence, evaluated from left to right.
Fourth  Addition and subtraction with equal precedence, evaluated from left to right.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

8. Examples >> 8 + 3*5 ans= 23 >> 8 + (3*5) >>(8 + 3)*555
>>4^ /4*2
>>4^ /(4*2) 3
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

9. Examples >> 3*4^2 + 5 ans= 53 >>(3*4)^2 + 5 149
>>27^(1/3) + 32^(0.2) 5
>>27^(1/3) + 32^0.2
>>27^1/3 + 32^0.2 11
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

10. The Assignment Operator =
Typing x = 3 assigns the value 3 to the variable x.
We can then type x = x + 2 This assigns the value = 5 to x. But in algebra this implies that 0 = 2.
In algebra we can write x + 2 = 20, but in MATLAB but in MATLAB we cannot.
In MATLAB the left side of the = operator must be a single variable.
The right side must be a computable value.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

11. Commands for managing the work session
Command  Description
clc Clears the Command window.
clear Removes all variables from memory.
clear v1 v Removes the variables v1and v2from memory.
exist (‘var’) Determines if a file or variable exists having the name ‘var’.
Quit Stops MATLAB.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

12. Commands for managing the work session
Who Lists the variables currently in memory.
Whos Lists the current variables and sizes, and indicates if they have
imaginary parts.
: Colon; generates an array having regularly spaced elements.
, Comma; separates elements of an array.
; Semicolon; suppresses screen printing; also denotes a new row
in an array.
Ellipsis; continues a line.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

13. Special Variables and Constants
Command Description
Ans Temporary variable containing the most recent answer.
Eps Specifies the accuracy of floating point precision.
i,j The imaginary unit √−1.
Inf Infinity.
NaN Indicates an undefined numerical result.
Pi The number π.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

14. Complex Number Operations
The number c1= 1 –2i is entered as follows:
c1 = 1-2i
An asterisk is not needed between i or j and a number, although it is required with a variable, such as
c2 = 5 - i*c1
Be careful. The expressions y = 7/2*i and x = 7/2i
give two different results:
y = (7/2)i = 3.5i
and
x = 7/(2i) = –3.5i.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

15. Numeric Display Formats
Command Description and Example
format short Four decimal digits
(the default);
format long digits;
format short e Five digits (four decimals)
plus exponent; e+03.
format long e digits (15 decimals)
plus exponent; e–04.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

16. Arrays
The numbers 0, 0.1, 0.2, …, 10 can be assigned to the variable u by typing u = [0:0.1:10].
To compute w= 5 sin u for u= 0, 0.1, 0.2, …, 10, the session is;
>>u = [0:0.1:10];
>>w = 5*sin (u);
The single line, w = 5*sin (u), computed the formula
w= 5 sin u101 times.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

17. Array Index >>u(7) ans= 0.6000 >>w(7) 2.8232
Use the length function to determine how many values are in an array.
>>m = length (w)
m =
101
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

18. Polynomial Roots
To find the roots of x3–7x2+ 40x–34 = 0, the session is
>>a = [1,-7,40,-34];
>>roots(a)
ans= i i
1.0000
The roots are x= 1 and x= 3 ± 5i.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

19. Some Commonly Used Mathematical
Function MATLAB syntax1
e exp(x)
√x sqrt(x)
lnx log(x)
log10x log10(x)
cosx cos(x)
Sin x sin(x)
tan x tan(x)
cos x acos(x)
sin x asin(x)
tan x atan(x) x -1 -1 -1
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

20. When you type problem1
MATLAB first checks to see if problem1 is a variable and if so, displays its value.
If not, MATLAB then checks to see if problem1 is one of its own commands, and executes it if it is.
If not, MATLAB then looks in the current directory for a file named problem1.m and executes problem1if it finds it.
If not, MATLAB then searches the directories in its search path, in order, for problem1.m and then executes it if found.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

21. System, Directory, and File Commands
Command Description
addpath dirname Adds the directory dirnameto the search path.
cd dirname Changes the current directory to dirname.
dir Lists all files in the current directory.
dir dirname Lists all the files in the directory dirname.
Path Displays the MATLAB search path.
Pathtool Starts the Set Path tool.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi

22. System, Directory, and File Commands
Command Description
Pwd Displays the current directory.
Rmpath dirname Removes the directory dirnamefrom
the search path.
What Lists the MATLAB-specificfiles found in
the current working directory. Most
data files and other non-MATLAB files
are not listed. Use dir to get a list of all files.
what dirname Lists the MATLAB-specific files in
directory dirname.
King Abdulaziz University EE Eng. Ghassan R. Alnwaimi