Getting Started with MATLAB and OCTAVE for engineers

© 2019 Dr.Rathishchandra.R.Gatti .
Getting Started with
MATLAB/Octave for Engineers
OCTAVE
Dr. Rathishchandra. R. Gatti
Professor- Mech. Engg
gattirathish@gmail.com
MATLAB is the registered trademark of Mathworks Inc.
GNU Octave is an Open source software.
1
Level 0

AGENDA
1. Introduction to MATLAB
2. Introduction to Octave
3. Some Hands-on Using Octave
2

OBJECTIVES OF THIS WORKSHOP
• To make you familiar with computational tools
that every engineer MUST know.
• To push you to learn these tools during your
holidays and use them next year for FY projects.
“NO MATH, NO ENGINEERING.
KNOW MATH, KNOW ENGINEERING.”
3

1. Introduction to MATLAB
• High level Programming language = Easy to
prototype language of your logic /algorithm.
• Extensive repository of Toolboxes and in-built
functions
• It is a commercial package with student and
commercial licenses.
• MATLAB = MATRIX + LAB . It is based on
Matrices and Vectors.
4

2. Introduction to OCTAVE
• High level Programming language = Easy to
prototype language of your logic /algorithm.
• Extensive repository of packages and in-built
functions. Downloadable .pkg files.
• It is completely OPEN SOURCE – FREE and
Source code can be edited .
• Used prominently in Scholarly institutes who
donot like someone else to build code for
them.
7

3. Opinion
• Both MATLAB and GNU Octave are good in
their own merits.
• Do not waste time by being a fanatic of either
commercial or open source. Be a fanatic of
“GETTING THINGS DONE” .
• Use what is available – SURVIVAL
INSTINCT.
9

GNU Octave
10

1. Downloading & Installing GNU Octave
11
Web clipped from https://www.gnu.org/software/octave/

12

13

2. Running GNU Octave
Command Line Interface
Graphical User Interface
14

a = [1 2 3….10]
b = a3+3a2+4a
Plot a v.s bCommand Line Interface
15

Graphical User Interface
16

Programming approaches
• Script level programming (.m files) – creating
M files for small programs.
• Functional programming- creating modules or
packages with several interdependent M
function files.
17

Two Script programming approaches :
Option 1 : First script and then run
commands
Option 2 : First evaluate commands
and then script
18

Option 1 : First script and then run commands
19

Option 2 : First evaluate commands and then script
20

Simple program #1
##OK let us write a program
a=[20,15,30;40 75,-40;30,23,67];
b=exp(4.*a);
21

x = -10:0.1:10; # Create an evenly-
spaced vector from -10..10
y = sin (x); # y is also a vector
plot (x, y);
title ("Simple 2-D Plot");
xlabel ("x");
ylabel ("sin (x)");
Simple program #2
Source : https://www.gnu.org/software/octave/#install
22

Simple program #3
x = -10:0.1:10; # Create an evenly-spaced
vector from -10..10
y = sin (x); # y is also a vector
z = cos(x);
plot3 (x, y, z);
title ("Simple 2-D Plot");
xlabel ("x");
ylabel ("sin (x)");
zlabel ("cos (x)");
24

Simple program #4
tx = ty = linspace (-8, 8, 41)';
[xx, yy] = meshgrid (tx, ty);
r = sqrt (xx .^ 2 + yy .^ 2) + eps;
tz = sin (r) ./ r;
mesh (tx, ty, tz);
xlabel ("tx");
ylabel ("ty");
zlabel ("tz");
title ("3-D Sombrero plot");
Source : https://www.gnu.org/software/octave/#install
27

Octave Use in Typical Theoretical Analysis
Theoretical equation
Numerical equation
Numerical solving
Numerical solution
Data visualisation and analysis
Convert to numerical equation using Laplace or
Statespace or any other methods
Convert to numerical equation using Laplace or
Statespace or any other methods
[x, istate, msg] = lsode (fcn, x_0, t)
[x, istate, msg] = lsode (fcn, x_0, t, t_crit)

Experiment
Setup
t = xlsread (‘Test.xls', ‘sheet1', 'C4:AB38');
XLS or CSV
format data
Data
Logger
Octave Use in Typical Experimentation
Sensors
q = t* Pi*C*d2;
XLS Data Visualisation

Octave Forge
This is like the
the play store of Octave apps
https://octave.sourceforge.io/packages.php
31

https://octave.sourceforge.io/packages.php
32

First to know if you already have packages
Type “ pkg list” and Hit enter
33

pkg install -forge package_name
pkg load package_name
pkg install -forge linear-algebra
pkg load linear-algebra
Format :
Example :
34

Source: https://octave.sourceforge.io/packages.php
35

Source: https://octave.sourceforge.io/packages.php
36

Not Enough time to explain …
Encourage you to contact any of us (faculty) and
learn as much as possible these tools before you
graduate.
Most importantly, USE THESE TOOLS before you
graduate.
Thank you 

Getting Started with MATLAB and OCTAVE for engineers

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