Chapter 1.pdf

INTRODUCTION TO MATLAB
NED University of Engineering & Technology

• Credit Hours: 2 + 1
• Course Learning Outcomes (CLOs):
Course Details
S.
No.
CLOs Taxonomy PLOs
Assessment
Tools
1
Understand and identify the fundamental
concepts of computer programming
C1 1
Test /Mid/
Final
2
Apply the acquired knowledge to
mechanical engineering problems
C3 2
Test /Mid/
Final
3
Practice the numerical analysis and
optimization on programming language
P3 5
Sessional
+Final
Practicals
4
For given Mechanical engineering
problems, execute the regression models
and make comparison of the predicted
and measured data
P4 3
Sessional
Practical

• Different windows in MATLAB
• Arithmetic operations with scalars using MATLAB.
• Scalar variables and their use in arithmetic
calculations
• Elementary Math built-in functions
• Script files → how to write, save, and execute
simple MATLAB programs
Outline
Textbook: A. Gilat, Matlab: An Introduction with Applications 4th Edition. John Wiley
& Sons, Incorporated, 2017. (Chapter 1: Introduction)

4 of 38
Prerequisites for solving a problem using MATLAB
• Mathematics
• An algorithm
• The exact rules for writing MATLAB statements
• Correct usage of MATLAB utilities
• Converting algorithm into MATLAB statements
and/or program

5 of 38
Default view of MATLAB desktop
COMMAND WINDOW
WORKSPACE
WINDOW
COMMAND HISTORY
WINDOW
CURRENT
FOLDER
WINDOW

6 of 38
Default view: Home → Layout → Default

7 of 38
• Main window: For executing commands
• Command line: The line with command prompt >>
Command Window: Executing commands one at a time
Command 1:A=5
press enter
Command 2: B=10
press enter
Command 3: C=A+B
press enter
To execute
each
command:
Press Enter
The cursor next to the command
prompt is prompting the user to enter
the next Command

8 of 38
Command Window: Executing several commands
3 commands in the same
line separated by a
comma
Order of
execution:
Left to Right

9 of 38
Command Window: Editing
• Editing:
The already executed command can not be corrected
and re-executed

10 of 38
Command Window: Editing
Command-line editing:
• Left-arrow, Right-arrow
• Up-arrow and Down-arrow for accessing history
• Smart recall: type some character and press
Up-arrow and Down-arrow

11 of 38
Command Window: Use of percent symbol (%)
Comment
Comment line is not executed when ENTER is
pressed
Comments are added to aid the programmer for his/her reference

12 of 38
Command Window: Use of Semi-colon (;)
Output of the command is displayed
Output of the command
is not displayed

13 of 38
Command Window: Use of Semi-colon (;)

14 of 38
Command Window: Use of the command clc
clc → clears the command window only
CAUTION: The commands are CASE-SENSITIVE!

15 of 38
Drawbacks of a command window
• The commands in the Command window
cannot be saved and executed again.
• It is not interactive.
• Already executed command can not be
modified
• Better option: script file

16 of 38
Command Window: Font size: Home → Preferences → Fonts

17 of 38
Useful commands you should know
CAUTION: The commands are CASE-SENSITIVE!
• help → lists all the primary help topics.
• help <command> → displays information about the command.
• doc On-line help → accesses the hypertext reference manual.
for this
• doc <command> → displays information about the command.
• type <command> → Displays the actual MATLAB code
command.
• lookfor <keyword> → Searches all MATLAB commands for this
keyword.

18 of 38
ATTENTION: The commands are CASE-SENSITIVE!
• who → Lists all the current variables.
• whos → Lists all the current variables in more detail than who.
• save → Saves all of your variables.
• ^C → Abort the command which is currently executing (i.e., hold down
the control key and type c).

19 of 38
ATTENTION: The commands are CASE-SENSITIVE!
• clc → clears the command window (but does not clear the saved
variables in the workspace)
• clear all → deletes all the saved variables from the workspace (but
does not clear the command window) and brings the cursor at top
• clear variable → deletes only that particular variable from the
workspace
• date → gives current date
• calendar→ shows up the calendar of the ongoing month

20 of 38
Busy…

21 of 38
Command History
• The Command History Window → includes commands from previous
sessions.
• A command in the Command History Window can be used again in the
Command Window.
• By double-clicking on the command, the command is reentered in the
Command Window and executed.
• It is also possible to drag the command to the Command Window, make
changes if needed, and then execute it.
• Clearing Command history:
• Whole history
• A selection

22 of 38
Simple Arithmetic Operations With Scalars
Addition: 3+2
Subtraction: 3-2
Multiplication: 3*2
Division: 3/2 or 23
Exponent: 3^2

23 of 38
Order of Precedence

24 of 38
Order of Precedence: Practice

25 of 38
Display formats
Command Description Example
format short
(default)
upto 4 decimal digits
>> 290/7
ans =
41.4286
format long upto 15 decimal digits
>> 290/7
ans =
41.4285714285
71431
format short e scientific notation with 4 decimal digits
>> 290/7
ans =
4.1429e+001
format long e scientific notation with 15 decimal digits
>> 290/7
ans =
4.14285714285
7143e+001

26 of 38
Example
Display formats
Command Description
format short g 5 s.g.f of floating digits
>> 290/7
ans =
41.429
format long g 15 s.g.f of floating digits
>> 290/7
ans =
41.4285714285
714
format bank upto 2 decimal digits
>> 290/7
ans =
41.43
format loose
(default)
Adds empty lines (opposite of compact).
format compact
Eliminates empty lines to allow more lines with information
displayed on the screen.

27 of 38
Display formats: compact vs loose

28 of 38
Inf & NaN
1/0
Infinity:
inf + 3
Not-a-Number (NaN):
0/0

29 of 38
Variables: Storing data
Save value in a variable:
x = 3
x = 4 (over-ridden)
Variables are case-sensitive:
T = 2
t = 3
Z = t+T;
Assignment
operator
=

30 of 38
Variables: Naming rules
1. May consist of:
✓ letters A-Z, a-z
✓ digits 0-9
✓ underscore ( _ )
2. Must start with a letter.
3. Variable names are case-sensitive
4. Can be up to 63 characters long
5. Avoid using the built-in functions as the variable
name e.g. cos, sin, sqrt etc.

31 of 38
Variables: Predefined keywords that can not be used as
variable name
for
function
global
if
otherwise
parfor
persistent
break
case
catch
classdef
continue
else
elseif
end
return
spmd
switch
try
while

32 of 38
Variables: Predefined variables
ans
pi
…

33 of 38
a = sqrt(4)
Elementary math built-in functions
A function has a name and an argument in parentheses.
a = 4

34 of 38
Elementary functions in MATLAB: Trigonometry
Function Description Example
sin(x)
sind(x)
Sine of angle x (x in radians).
Sine of angle x (x in degrees).
>> sin(pi/6)
ans =
0.5
cos(x)
cosd(x)
Cosine of angle x (x in radians).
Cosine of angle x (x in degrees).
>> cosd(30)
ans =
0.86603
tan(x)
tand(x)
Tangent of angle x (x in radians).
Tangent of angle x (x in degrees).
>> tan(pi/6)
ans =
0.57735
cot(x)
cotd(x)
Cotangent of angle x (x in radians).
Cotangent of angle x (x in degrees).
>> cotd(30)
ans =
1.7321

35 of 38
Elementary functions in MATLAB: Trigonometry
• Inverse trigonometric functions are:
asin(x), acos(x), atan(x), acot(x) for the angle in
radians.
asind(x), acosd(x), atand(x),acotd(x) for the angle
in degrees.
•Hyperbolic trigonometric functions are
sinh(x), cosh(x), tanh(x), and coth(x).

36 of 38
Elementary functions in MATLAB: Exponential
sqrt(x) square root
>> sqrt(81)
ans =
9
nthroot(x,n) Real nth root of a real number x.
>> nthroot(80,5)
ans =
2.4022
exp(x) Exponential ex
>> exp(5)
ans =
148.41
3
log(x) Natural logarithm.
>> log(1000)
ans =
Base e logarithm (ln). 6.9078
log10(x) Base 10 logarithm.
>> log10(1000)
ans =

37 of 38
Elementary functions in MATLAB: Rounding & Remainder
round(x) Rounds to the nearest integer.
>>
round(3/2)
ans =
2
fix(x) Rounds towards zero.
>> fix(3/2)
ans =
1
ceil(x) Rounds towards +ve infinity.
>>
ceil(3/2)
ans =
2
floor(x) Rounds towards -ve infinity.
>>
floor(3/2)
ans =
1
rem(x,y) Returns the remainder after x is divided by y.
>>
rem(35,3)
ans =
2
sign(x) Signum function. Returns 1 if x > 0, -1 if x < -1 & 0 if x =0
>> sign(5)
ans =
1

38 of 38
Practice …..
fix and rem
Converting 40 inches to feet-inch.
feet = fix(40/12)
inches = rem(40, 12)

Chapter 1.pdf

Recommended

Recommended

More Related Content

Similar to Chapter 1.pdf

Similar to Chapter 1.pdf (20)

Recently uploaded

Recently uploaded (20)

Chapter 1.pdf