Getting started with octave

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Remarks

This section provides an overview of what octave is, and why a developer might want to use it.

It should also mention any large subjects within octave, and link out to the related topics. Since the Documentation for octave is new, you may need to create initial versions of those related topics.

Hello World

  1. start Octave by running the command octave (the executable should be in your path)

  2. type disp('Hello, World!') at the Octave command prompt

>> disp('Hello, World!')
Hello, World!
 

Installation or Setup

Instructions on getting octave set up or installed.

Installing Octave for debian systems (Debian, Ubuntu):

Simple: sudo apt-get install octave

Advanced: Well, if you want to install other external packages

sudo apt-get install octave-control octave-image octave-io octave-optim octave-signal octave-statistics
 

For furter details like

  • install from PPA.
  • install from sources, etc.

A very good detailed wikis are present in Octave's wiki pages

  • For Debian or Ubuntu look at this - wiki

  • For Windows have a look at this - wiki

  • And for Mac OS X look at this - wiki

Matrices

Create a 2x3 matrix. Each row is a comma-separated list of elements. Rows are separated by a semicolon.

A = [1, 2, 3; 4, 5, 6]

# A =
#
#   1   2   3
#   4   5   6
 

Sum of two matrices

B = [1, 1, 1; 1, 1, 1]

# B =
#
#    1   1   1
#    1   1   1

A+B

# ans =
#
#   2   3   4
#   5   6   7
 

Multiply matrix by a scalar

2*A

# ans =
#
#    2    4    6
#    8   10   12
 

Matrix multiplication

C = [1, 0; 0, 0; 0, 1]

# C =
#
#   1   0
#   0   0
#   0   1

A*C

# ans =
#
#   1   3
#   4   6
 

A matrix can be a column vector

C = [2; 0; 1]

# C =
#
#   2
#   0
#   1

A * C
# ans =
# 
#     5
#    14
 

Concatenating matrices

For horizontal concatenation, that is joining two block matrices column-wise

A= [1,2;3,4]; 
B=[4,3;2,1];
C=horzcat(A,B);
disp(C)
# C=
#
# 1 2 4 3 
# 3 4 2 1 




 

Reading commands from a script file

Octave commands can be saved in a file and evaluated by loading the file using source .

For instance, let hello.m be the text file containing two lines (the first line is a comment)

# my first Octave program
disp('Hello, World!')
 

If you type source hello.m at an Octave command prompt you will get

>> source hello.m
Hello, World!
 

Note that a script file doesn't necessarily have to have the extension .m .

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Saturday, April 22, 2017
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