1. MATLAB DENC 2533 ECADD
LAB 9

2. OUTLINE INTRO MATLAB SYSTEM MATLAB WINDOW
MATLAB IN MATHEMATICAL OPERATION
GRAPHIC ON MATLAB
MATLAB EDITOR FILE (M-file)
PROGRAMMING IN MATLAB

3. Introduction MATLAB stand for MATrix LABoratory.
High performance language for technical computing.
It integrates computation, visualization and programming.
Typical uses in:
Math and computation
Algorithm development
Modeling, simulation and prototyping
Data analysis, exploration and visualization
Scientific and engineering graphics
Application development

4. MATLAB System
Development environment – command window, command history, editor, debugger, browsers for help, workspace file.
MATLAB mathematical function library – function like sum, sine, cosine and complex arithmetic, matrix.
MATLAB language – high level matrix/array language with control flow statements, functions, data structure, I/O.
Graphics – presentation graphics, image processing, data visualization.
MATLAB application program interface (API) – a library that allows to write C and FORTRAN programs that interact with MATLAB.

5. Starting MATLAB When you start MATLAB, 4 windows appear by default:
MATLAB Command Window
Current Directory Window
Workspace Window
Command History Window

6. 1) MATLAB Command Window
To communicate with MATLAB program, use MATLAB command window.
MATLAB display the prompt (>> ) to indicate that it is ready to receive instructions.

7. ii) Current Directory Window
It is much like a file manager window.
Used to access files
For example: file.m – it will open file in Matlab editor.

8. iii) Workspace Window
Display the variables created in the command window
Workspace refers to the names and values of any variable in use in the current work session.

9. Command History Window
All the previous instruction/programming entered in MATLAB command window showed here
You can double click and drag the command into the MATLAB command window or Matlab editor.

10. Entering Command and Expressions
Example of command s in Matlab Command Window:
>> x=[0:002:8];
>> y=5*sin(x);
>> plot(x,y):
When you put semicolon (;) at the end of your command line, Matlab will not shows the answer of your commands/expressions.
Example of mathematical expressions in Matlab prompt without semicolon(;) :
>> 8/10
ans =
>> 5*anw
ans = 4

11. Variables A variable in Matlab is a symbol used to contain a value.
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.
Scalar variable:
>> r=8/10
r =
>> s=5*r
s = 4
>> 3 + 9
ans = 12

12. Variables (cont.)
Variable names must begin with a letter and must contain less than 32 characters; contain letter, digits, and underscore.
Matlab is case-sensitive, the following names represent different variables: speed, Speed, SPEED.
Special variables and built-in constants in matlab:
ans, i , j, inf, NaN, pi

13. Scalar Arithmetic Operations:
SYMBOL
OPERATION
MATLAB FORM +
Addition: a + b
a + b -
Subtraction: a – b
a – b *
Multiplication: a b
a*b /
Right division: a/b
a/b \
Left division: b\a
b\a ^
Exponentiation: ab
a^b

14. Commands for managing the MATLAB
Operation
clc
Clear the command window
clear
Removes all variables from memory
clear var1
Remove the var1
quit
Stop matlab
who
List the variables currently in memory
whos
List current variable and its size in memory
; (semicolon)
Indicate the ends of the rows of a matrix or use after statement to suppress printing
: (colon)
used to pick out selected rows, columns
and elements of vectors, matrices, and arrays ,
separator %
comment

15. Computing with MATLAB
Matlab able to handle collection of numbers, called array.
Example of array variable:
>> x= [ ]; % 4-sequence of array
>> u= [0 1; 2 1]; % 2x2 matrix
>> y= [0:0.01:2];
>> length (y); % check total number of sequence-y
>> y(7); % check the value of y in array-7
Define polynomial x2 + 2x + 1, to find roots of the polynomial:
>> a= [1, 2, 1];
>> roots (a)
Answer: roots of a: x= -1 , x= -1
 So, the polynomial a is (x+1)(x+1)

16. Computing with MATLAB (cont.)
Built-in and User Defined Functions
Function
MATLAB Syntax ex
exp (x) √x
sqrt (x)
ln x
log (x)
log10 x
log10 (x)
cos x
cos (x)
sin x
sin (x)
tan x
Tan (x)
cos-1 x
acos (x)
sin-1 x
asin (x)
tan-1 x
atan (x)

17. Matlab Scripting files & the Editor/Debugger
Matlab can perform operations in 2 ways:
Using Matlab Command Window
Using Editor/Debugger (.m file)

18. MATLAB Editor M-file (.m)
All program and function files are saved using Matlab editor.
Writing M-files will enhance your problem solving productivity since many MATLAB commands can be run from one file without having to enter each command one-by-one at the MATLAB prompt. This way, corrections and changes can be made in the M-file and re-run easily.
 Using the MATLAB Script Editor (click FileNewM-file)

19. Plotting with Matlab/Graphics
Matlab contains many powerful functions for easily creating plots of several different types.
Try this session:
>> x=[0:0.001:10];
>> y=sin(2*x);
>> figure(1);
>> plot(x,y);
>> xlabel(‘paksi-x’), ylabel(‘paksi-y’);
>> title(‘plot y=sin 2x’);

20. Plotting with Matlab/Graphics (cont.)
Command MATLAB
Operation
figure
Create a new graph/figure
plot( x, y)
Draw the graph
title('text')
Define a title for a graph
xlabel('text')
Define a x-axis for a graph
ylabel('text')
Define a y-axis for a graph
grid
Setting grid lines at graph
stem (x,y)
plot a graph in a discrete sequence format
mesh (x,y,z)
Plot graph in three dimensional plots

21. PROGRAMMING IN MATLAB Flow control: if statement
if statements evaluates a logical expression and executes a group of statements when the expression is true.
Eg:
If A > B
‘greater’
elseif A < B
‘less’
elseif A == B
‘equal’
else
‘unknown error’
end

22. PROGRAMMING IN MATLAB (cont.)
for statement
- for loop repeats a group of statements a fixed, predetermined number of times.
Eg:
m = 0
for n = 3:32
m = m + n
end m

23. PROGRAMMING IN MATLAB (cont.)
while statement
while loop repeats a group of statements an indefinite number of times under control of a logical condition.
Eg:
a = 0
b = 10
while b > a
b = b – 1;
end a b