GNU Octave

Name	GNU Octave
Logo
Screenshot
Caption	GNU Octave 4.3.0+ running on Linux
Developer	John W. Eaton and many others
Released	(first alpha release) (version 1.0)
Programming Language	C++ (main), Octave itself (scripts), C (wrapper code), Fortran (linear algebra wrapper code)
Operating System	Windows, macOS, Linux, BSD
Language Count	18
Genre	Scientific computing
License	2007: GPL-3.0-or-later 1992: GPL-2.0-or-later
Website	https://octave.org/

History

The project was conceived around 1988. At first it was intended to be a companion to a chemical reactor design course. Full development was started by John W. Eaton in 1992. The first alpha release dates back to 4 January 1993 and on 17 February 1994 version 1.0 was released. Version 9.2.0 was released on 7 June 2024.

The program is named after Octave Levenspiel, a former professor of the principal author. Levenspiel was known for his ability to perform quick back-of-the-envelope calculations.

Development history

Developments

In addition to use on desktops for personal scientific computing, Octave is used in academia and industry. For example, Octave was used on a massive parallel computer at Pittsburgh Supercomputing Center to find vulnerabilities related to guessing social security numbers.

Acceleration with OpenCL or CUDA is also possible with use of GPUs.

Technical details

• Octave is written in C++ using the C++ standard library.
• Octave uses an interpreter to execute the Octave scripting language.
• Octave is extensible using dynamically loadable modules.
• Octave interpreter has an OpenGL-based graphics engine to create plots, graphs and charts and to save or print them. Alternatively, gnuplot can be used for the same purpose.
• Octave includes a graphical user interface (GUI) in addition to the traditional command-line interface (CLI); see #User interfaces for details.

Octave, the language

The Octave language is an interpreted programming language. It is a structured programming language (similar to C) and supports many common C standard library functions, and also certain UNIX system calls and functions. However, it does not support passing arguments by reference although function arguments are copy-on-write to avoid unnecessary duplication.

Octave programs consist of a list of function calls or a script. The syntax is matrix-based and provides various functions for matrix operations. It supports various data structures and allows object-oriented programming.

Its syntax is very similar to MATLAB, and careful programming of a script will allow it to run on both Octave and MATLAB.

Because Octave is made available under the GNU General Public License, it may be freely changed, copied and used. The program runs on Microsoft Windows and most Unix and Unix-like operating systems, including Linux, Android, and macOS.

Notable features

Command and variable name completion

Typing a TAB character on the command line causes Octave to attempt to complete variable, function, and file names (similar to Bash's tab completion). Octave uses the text before the cursor as the initial portion of the name to complete.

Command history

When running interactively, Octave saves the commands typed in an internal buffer so that they can be recalled and edited.

Data structures

Octave includes a limited amount of support for organizing data in structures. In this example, we see a structure

x

a

b

c

octave:1> x.a = 1; x.b = [1, 2; 3, 4]; x.c = "string";
octave:2> x.a
ans =  1
octave:3> x.b
ans =

   1   2
   3   4

octave:4> x.c
ans = string
octave:5> x
x =

  scalar structure containing the fields:

    a = 1
    b =

       1   2
       3   4

    c = string

Short-circuit Boolean operators

Octave's && and || logical operators are evaluated in a short-circuit fashion (like the corresponding operators in the C language), in contrast to the element-by-element operators & and |.

Increment and decrement operators

Increment and decrement operators
Octave includes the C-like increment and decrement operators ++ and -- in both their prefix and postfix forms.

Octave also does augmented assignment, e.g. x += 5.

Unwind-protect

Octave supports a limited form of exception handling modelled after the unwind_protect of Lisp. The general form of an unwind_protect block looks like this:

unwind_protect
   body
unwind_protect_cleanup
   cleanup
end_unwind_protect

try
   body
catch
   exception_handling
end

Variable-length argument lists

Octave has a mechanism for handling functions that take an unspecified number of arguments without explicit upper limit. To specify a list of zero or more arguments, use the special argument varargin as the last (or only) argument in the list. varargin is a cell array containing all the input arguments.

function s = plus (varargin)
   if (nargin==0)
      s = 0;
   else
      s = varargin{1} + plus (varargin{2:nargin});
   end
end

Variable-length return lists

A function can be set up to return any number of values by using the special return value varargout. For example:

function varargout = multiassign (data)
   for k=1:nargout
      varargout{k} = data(:,k);
   end
end

C++ integration

It is also possible to execute Octave code directly in a C++ program. For example, here is a code snippet for calling rand([10,1]):

#include <octave/oct.h>
...
ColumnVector NumRands(2);
NumRands(0) = 10;
NumRands(1) = 1;
octave_value_list f_arg, f_ret;
f_arg(0) = octave_value(NumRands);
f_ret = feval("rand", f_arg, 1);
Matrix unis(f_ret(0).matrix_value());

{{anchor|MATLAB}} MATLAB compatibility

Octave has been built with MATLAB compatibility in mind, and shares many features with MATLAB:

1. Matrices as fundamental data type.
2. Built-in support for complex numbers.
3. Powerful built-in math functions and extensive function libraries.
4. Extensibility in the form of user-defined functions.

Syntax compatibility

There are a few purposeful, albeit minor, syntax additions Archived 2012-04-26, at web.archive.org:

1. Comment lines can be prefixed with the # character as well as the % character;
2. Various C-based operators Increment operator|++, Decrement operator|--, Augmented assignment|+=, *=, /= are supported;
3. Elements can be referenced without creating a new variable by cascaded indexing, e.g. 1:10(3);
4. Strings can be defined with the double-quote " character as well as the single-quote ' character;
5. When the variable type is single (a single-precision floating-point number), Octave calculates the "mean" in the single-domain (MATLAB in double-domain) which is faster but gives less accurate results;
6. Blocks can also be terminated with more specific Control structure keywords, i.e., endif, endfor, endwhile, etc.;
7. Functions can be defined within scripts and at the Octave prompt;
8. Presence of a do-until loop (similar to do-while in C).

Function compatibility

Many, but not all, of the numerous MATLAB functions are available in GNU Octave, some of them accessible through packages in Octave Forge. The functions available as part of either core Octave or Forge packages are listed online Archived 2024-03-14, at web.archive.org.

A list of unavailable functions is included in the Octave function __unimplemented.m__. Unimplemented functions are also listed under many Octave Forge packages in the Octave Wiki.

When an unimplemented function is called the following error message is shown:

octave:1> guide
  warning: the 'guide' function is not yet implemented in Octave

  Please read <http://www.octave.org/missing.html> to learn how you can contribute missing functionality.
  error: 'guide' undefined near line 1 column 1

User interfaces

Octave comes with an official graphical user interface (GUI) and an integrated development environment (IDE) based on Qt. It has been available since Octave 3.8, and has become the default interface (over the command-line interface) with the release of Octave 4.0.

It was well-received by an EDN contributor, who wrote "Octave now has a very workable GUI" in reviewing the then-new GUI in 2014.

Several 3rd-party graphical front-ends have also been developed, like ToolboX for coding education.

GUI applications

With Octave code, the user can create GUI applications. See GUI Development (GNU Octave (version 7.1.0)). Below are some examples:
Button, edit control, checkbox

# create figure and panel on it
f = figure;
# create a button (default style)
b1 = uicontrol (f, "string", "A Button", "position",[10 10 150 40]);
# create an edit control
e1 = uicontrol (f, "style", "edit", "string", "editable text", "position",[10 60 300 40]);
# create a checkbox
c1 = uicontrol (f, "style", "checkbox", "string", "a checkbox", "position",[10 120 150 40]);

prompt = {"Width", "Height", "Depth"};
defaults = {"1.10", "2.20", "3.30"};
rowscols = [1,10; 2,20; 3,30];
dims = inputdlg (prompt, "Enter Box Dimensions", rowscols, defaults);

my_options = {"An item", "another", "yet another"};
[sel, ok] = listdlg ("ListString", my_options, "SelectionMode", "Multiple");
if (ok == 1)
  msgbox ("You selected:");
  for i = 1:numel (sel)
    msgbox (sprintf ("\t%s", my_options{sel(i)}));
  endfor
else
  msgbox ("You cancelled.");
endif

# create figure and panel on it
f = figure;
# create a button group
gp = uibuttongroup (f, "Position", [ 0 0.5 1 1])
# create a buttons in the group
b1 = uicontrol (gp, "style", "radiobutton", "string", "Choice 1", "Position", [ 10 150 100 50 ]);
b2 = uicontrol (gp, "style", "radiobutton", "string", "Choice 2", "Position", [ 10 50 100 30 ]);
# create a button not in the group
b3 = uicontrol (f, "style", "radiobutton","string", "Not in the group","Position", [ 10 50 100 50 ]);

Packages

Octave also has many packages available. Those packages are located at Octave-Forge Octave Forge - Packages, or GitHub Octave Packages. It is also possible for anyone to create and maintain packages.

Comparison with other similar software

Alternatives to GNU Octave under an open source license, other than the aforementioned MATLAB, include Scilab and FreeMat. Octave is more compatible with MATLAB than Scilab is, and FreeMat has not been updated since June 2013.

Also the Julia programming language and its plotting capabilities has similarities with GNU Octave.

See also

• List of numerical-analysis software
• Comparison of numerical-analysis software
• List of statistical packages
• List of numerical libraries

Notes

References

• contributors.in, Rik, 14 June 2015, 10 June 2015
• "Full-time development began in the Spring of 1992. The first alpha release was January 4, 1993, and version 1.0 was released February 17, 1994."
• Building - Octave, wiki.octave.org, GNU, 1 May 2018, en
• Basque, Belarusian, Catalan, Chinese, Dutch, English, French, German, Hungarian, Italian, Japanese, Latvian, Portuguese (Brazil), Portuguese (Portugal), Russian, Spanish, Turkish, Ukrainian, hg.savannah.gnu.org
• About GNU Octave, www.gnu.org, GNU, 1 May 2018
• 2024-06-07, Octave 9.2.0 Released, 2024-11-05, octave.org, en
• Eaton, John W, About Octave, 2009-06-28
• GNU Octave Version 1, www.gnu.org
• GNU Octave Version 2, www.gnu.org
• GNU Octave Version 3, www.gnu.org
• GNU Octave Version 4.0, www.gnu.org
• GNU Octave 4.0.0 Released, www.gnu.org, 29 May 2015
• GNU Octave 4.0.1 Released, www.gnu.org, 23 March 2016
• GNU Octave 4.0.3 Released, www.gnu.org, 2 July 2016
• GNU Octave Version 5, www.gnu.org
• GNU Octave 6.1.0 Released, www.gnu.org, 26 November 2020
• GNU Octave 7.1.0 Released, www.gnu.org, 6 April 2022
• GNU Octave 8.1.0 Released, octave.org, 7 March 2023
• GNU Octave Version 9, 2024-03-25, octave.org, en
• Octave 9.2.0 released, 2024-11-05, octave.org, 7 June 2024, en
• Social Security Number Vulnerability Findings Relied on Supercomputing, 8 July 2009, 29 February 2012
• Drop-in Acceleration of GNU Octave, June 5, 2014, NVIDIA Developer Blog
• GNU Octave - Controlling subprocesses, 2009-01-28, 14 November 2008, 7 January 2009, dead
• GNU Octave, 2009-01-28
• Summary of important user-visible changes for version 3.2, 2012-01-05
• FAQ: MATLAB compatibility, 2009-04-04, 2011-11-21, dead
• FAQ: Getting Octave, 2009-04-04, 2011-11-21, dead
• Top (GNU Octave (version 6.3.0)), octave.org
• Octave for Android - Octave, 2021-08-23, wiki.octave.org
• Letting Readline Type For You, GNU Octave Reference Manual, Eaton, John W., 2016-07-29, 2018-02-12, dead
• FAQ - Octave, 2022-12-05, wiki.octave.org
• MATLAB Central Terms of Use, 2022-12-05, www.mathworks.com, en
• File Exchange Licensing FAQ, 2022-12-05, www.mathworks.com, en
• GNU Octave Version 3.8, www.gnu.org
• Hageman, Steve, 7 February 2014, GNU Octave hits a high note, EDN
• Trappenberg, Thomas, Fundamentals of Computational Neuroscience, 2010, Oxford University Press
• Muhammad, A, Zalizniak, V, Practical Scientific Computing, limited, 2011, Woodhead Publishing
• Megrey, Bernard A., Moksness, Erlend, Computers in Fisheries Research, limited, 2008, Springer Science & Business Media
• Kapuno, Raul Raymond, Programming for Chemical Engineers Using C, C++, and MATLAB, 2008, Jones & Bartlett Publishers
• Herman, Russell L., A Course in Mathematical Methods for Physicists, 2013, CRC Press
• Wouwer, Alain Vande, Saucez, Philippe, Vilas, Carlos, Simulation of ODE/PDE Models with MATLAB, Octave and Scilab: Scientific and Engineering Applications, 2014, Springer, 114–115
• FreeMat, freemat.sourceforge.net, 22 February 2020

Further reading

External links