Chapter 1 _ Introduction to Matlab.pptx

Chapter 1
Introduction to Matlab

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

Starting Matlab
Menu names
Toolbar
Directory
Desktop

Desktop Layout

Default

Starting Matlab
In Command window

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)

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

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.

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)

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.

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

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.

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

Symbol Operation Matlab form
^
*
/

+
-
Exponentiation: ab
Multiplication: ab
Right division: a/b
Left division: ab
Addition: a+b
Subtraction: a-b
a^b
a*b
a/b
ab
a+b
a-b
Order of Precedence
A scalar is a single number.
A scalar variable is a variable that contains a
single number.
Scalar arithmetic operations

Precedenc
e
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.
Order of Precedence
Order of precedence
Parentheses can be used to alter this order.

Order of Precedence

  
 
  3
5
/
4
2
2
4
2
5
2
14
60
5
319
4
27
.
14
53
9
55
2
.
48
.
145
7
4
7
6
4
3
.







c
b
a
Order of Precedence
Practice:
Use Matlab to calculate
a. 209.8333
b. -15.7028
c. 202.4120

The Assignment Operator

The Assignment Operator
Example:
The volume of a sphere is given by V=4r3
/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.

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,...

Defining variables

Rules for variables

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

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

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

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

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;

Complex Number Operations
addition
multiplication
subtraction
division
complex conjugate

Formatting command

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

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

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

Example:
Overview on Arrays

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: 4x3
– 8x2
+ 7x -5 can be represented by

Built –in Functions

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.

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 10th
element.
2. Create a new array taking the values from the
4th
to 8th
element.
3. Calculate sum of the first three elements of the
new array.

Chapter 1 _ Introduction to Matlab.pptx

Chapter 1 _ Introduction to Matlab.pptx

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Chapter 1 _ Introduction to Matlab.pptx