GNU Octave

GNU Octave is a high-level programming language primarily intended for scientific computing and numerical computation. Octave helps in solving linear and nonlinear problems numerically, and for performing other numerical experiments using a language that is mostly compatible with MATLAB. It may also be used as a batch-oriented language. As part of the GNU Project, it is free software under the terms of the GNU General Public License.

GNU Octave
Developer(s)John W. Eaton and many others[1]
Initial release4 January 1993 (4 January 1993) (first alpha release)
17 February, 1994 (17 February, 1994) (version 1.0)[2]
Stable release
7.2.0[3][4]  / 28 July 2022
Repository
Written inC++ (main), Octave itself (scripts), C (wrapper code), Fortran (linear algebra wrapper code)[5]
Operating systemWindows, macOS, Linux, BSD
Available in18 languages[6]
TypeScientific computing
License2007: GPL-3.0-or-later[lower-alpha 1]
1992: GPL-2.0-or-later[lower-alpha 2]
Websitegnu.org/software/octave/

History

The project was conceived around 1988.[7] 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 7.1.0 was released on Apr 6, 2022.[8]

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.[9]

Development history
TimeAction
1988/19891st discussions (Book and Software)
February 1992Start of Development
January 1993News in Web (Version 0.60)
February 19941st Publication (Version 1.0.0 to 1.1.1)[10]
December 19962nd Publication (Version 2.0.x) with Windows Port (Cygwin)[11]
March 1998Version 2.1
November 2004Version 2.9 (DEV Version of 3.0)[12]
December 2007Publication of Version 3.0 (Milestone)[13]
June 2009Publication of Version 3.2 (Milestone)[14]
8 February 2011Version 3.4.0 (Milestone)[15]
22 February 2012Publication of Octave 3.6.1 (Milestone)[16][17]
31 December 2013Publication of Octave 3.8.0 (experimental GUI)[18][19][20]
29 May 2015Version 4.0.0 (stable GUI and new Syntax for OOP)[21][22][23][24]
14 November 2016Version 4.2.0 (gnuplot 4.4+)[25][26][27][28]
30 April 2018Version 4.4.0 (new Goal for GUI QT Toolkit, the FLTK toolkit is not deprecated and there is no schedule for its removal - while no longer prioritized)[29][30][31]
1 March 2019Publication of Octave 5.1.0 (QT5 preferred, Qt 4.8 minimum), hiDpi support[32]
31 January 2020Publication of Octave 5.2.0 (QT5 preferred)[33]
26 November 2020Publication of Octave 6.1.0 (QT5 preferred, Qt 4.x deprecated for remove in 7)[34]
20 February 2021Publication of Octave 6.2.0 (QT5 preferred), Bugfix, improved matlab syntax support[35]
6 April 2022Publication of Octave 7.1.0 (QT5 preferred), improved graphics backend and matlab function compatibility[36]

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.[37]

Acceleration with OpenCL or CUDA is also possible with use of GPUs.[38]

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.[39] However, it does not support passing arguments by reference[40] 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.[41]

Its syntax is very similar to MATLAB, and careful programming of a script will allow it to run on both Octave and MATLAB.[42]

Because Octave is made available under the GNU General Public License, it may be freely changed, copied and used.[9] The program runs on Microsoft Windows and most Unix and Unix-like operating systems, including Linux, Android, and macOS.[43][44][45]

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.[46]

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 with elements a, b, and c, (an integer, an array, and a string, respectively):

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 =
{
  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

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

As a general rule, GNU Octave recognizes as termination of a given block either the keyword end (which is compatible with the MATLAB language) or a more specific keyword end_block. As a consequence, an unwind_protect block can be terminated either with the keyword end_unwind_protect as in the example, or with the more portable keyword end.

The cleanup part of the block is always executed. In case an exception is raised by the body part, cleanup is executed immediately before propagating the exception outside the block unwind_protect.

GNU Octave also supports another form of exception handling (compatible with the MATLAB language):

try
   body
catch
   exception_handling
end

This latter form differs from an unwind_protect block in two ways. First, exception_handling is only executed when an exception is raised by body. Second, after the execution of exception_handling the exception is not propagated outside the block (unless a rethrow( lasterror ) statement is explicitly inserted within the exception_handling code).

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.

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());

C and C++ code can be integrated into GNU Octave by creating oct files, or using the MATLAB compatible MEX files.

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.

Octave treats incompatibility with MATLAB as a bug; therefore, it could be considered a software clone, which does not infringe software copyright as per Lotus v. Borland court case.

MATLAB scripts from the MathWorks' FileExchange repository in principle are compatible with Octave. However, while they are often provided and uploaded by users under an Octave compatible and proper open source BSD license, the FileExchange Terms of use prohibit any usage beside MathWorks' proprietary MATLAB.[47][48][49]

Syntax compatibility

There are a few purposeful, albeit minor, syntax additions:

  1. Comment lines can be prefixed with the # character as well as the % character;
  2. Various C-based operators ++, --, +=, *=, /= 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.

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,[18] and has become the default interface (over the command line interface) with the release of Octave 4.0.[21] It was well-received by EDN contributor, who said "[Octave] now has a very workable GUI."[50]

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]);

Textbox

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);

Listbox with message boxes.

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

Radiobuttons

# 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

Other free alternatives to MATLAB include Scilab and FreeMat.[51][52][53][54] Octave is more compatible with MATLAB than Scilab is,[51][55][56] and FreeMat has not been updated since June 2013.[57]

See also
  • List of numerical-analysis software
  • Comparison of numerical-analysis software
  • List of statistical packages
  • List of numerical libraries
  • MATLAB

Notes
  1. GPL-3.0-or-later since 2007-10-12.
  2. GPL-2.0-or-later from 1992-02-19 until 2007-10-11.

References
  1. Rik (10 June 2015). "contributors.in". Retrieved 14 June 2015.
  2. ""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."".
  3. "GNU Octave 7.2.0 Released". 28 July 2022. Retrieved 3 August 2022.
  4. John W. Eaton (28 July 2022). "Version 7.2.0 released". Retrieved 3 August 2022.
  5. "Building - Octave". wiki.octave.org. GNU. Retrieved 1 May 2018.
  6. "Basque, Belarusian, Catalan, Chinese, Dutch, English, French, German, Hungarian, Italian, Japanese, Latvian, Portuguese (Brazil), Portuguese (Portugal), Russian, Spanish, Turkish, Ukrainian". hg.savannah.gnu.org.
  7. "About GNU Octave". www.gnu.org. GNU. Retrieved 1 May 2018.
  8. ""Version 7.1.0 released. Date: Wed, 06 Apr 2022 10:05:12 -0400"".
  9. Eaton, John W. "About Octave". Retrieved 2009-06-28.
  10. "GNU Octave Version 1". www.gnu.org.
  11. "GNU Octave Version 2". www.gnu.org.
  12. "News Archive". www.gnu.org.
  13. "GNU Octave Version 3". www.gnu.org.
  14. "GNU Octave Version 3.2". www.gnu.org.
  15. "GNU Octave Version 3.4". www.gnu.org.
  16. "GNU Octave Version 3.6". www.gnu.org.
  17. "GNU Octave 3.6.4 Released". www.gnu.org.
  18. "GNU Octave Version 3.8". www.gnu.org.
  19. "GNU Octave 3.8.0 Released". www.gnu.org.
  20. "GNU Octave 3.8.1 Released". www.gnu.org.
  21. "GNU Octave Version 4.0". www.gnu.org.
  22. "GNU Octave 4.0.0 Released". www.gnu.org.
  23. "GNU Octave 4.0.1 Released". www.gnu.org.
  24. "GNU Octave 4.0.3 Released". www.gnu.org.
  25. "GNU Octave 4.2.0 Released". Nov 14, 2016.{{cite web}}: CS1 maint: url-status (link)
  26. "GNU Octave Version 4.2". www.gnu.org.
  27. "GNU Octave 4.2.1 Released". www.gnu.org.
  28. "GNU Octave 4.2.2 Released". www.gnu.org.
  29. "GNU Octave Version 4.4". www.gnu.org.
  30. "GNU Octave 4.4.0 Released". www.gnu.org.
  31. "GNU Octave 4.4.1 Released". www.gnu.org.
  32. "GNU Octave Version 5". www.gnu.org.
  33. "GNU Octave 5.2.0 Released". www.gnu.org.
  34. "GNU Octave 6.1.0 Released". www.gnu.org.
  35. "GNU Octave 6.2.0 Released". www.gnu.org.
  36. "GNU Octave 7.1.0 Released". www.gnu.org.
  37. "Social Security Number Vulnerability Findings Relied on Supercomputing". 8 July 2009. Archived from the original on 29 February 2012.
  38. "Drop-in Acceleration of GNU Octave". NVIDIA Developer Blog. June 5, 2014.
  39. "GNU Octave - Controlling subprocesses". 14 November 2008. Archived from the original on 7 January 2009. Retrieved 2009-01-28.
  40. "GNU Octave". Retrieved 2009-01-28.
  41. "Summary of important user-visible changes for version 3.2". Retrieved 2012-01-05.
  42. "FAQ: MATLAB compatibility". Retrieved 2009-04-04.
  43. "FAQ: Getting Octave". Retrieved 2009-04-04.
  44. "Top (GNU Octave (version 6.3.0))". octave.org.
  45. "Octave for Android - Octave". wiki.octave.org. Retrieved 2021-08-23.
  46. Eaton, John W. "Letting Readline Type For You". GNU Octave Reference Manual.
  47. Why can't I use code from File Exchange in Octave? It's released under a BSD license! on octave.org
  48. terms of use on mathworks.com "Content that you submit must not directly compete with products offered by MathWorks. Content submitted to File Exchange may only be used with MathWorks products."
  49. File Exchange Licensing Transition FAQ on mathworks.com
  50. "GNU Octave hits a high note – Steve Hageman, 7 February 2014".
  51. Trappenberg, Thomas (2010). Fundamentals of Computational Neuroscience. Oxford University Press. p. 361. ISBN 978-0-19-956841-3.
  52. Muhammad, A; Zalizniak, V (2011). Practical Scientific Computing. Woodhead Publishing. p. 3. ISBN 978-0-85709-226-7.
  53. Megrey, Bernard A.; Moksness, Erlend (2008). Computers in Fisheries Research. Springer Science & Business Media. p. 345. ISBN 978-1-4020-8636-6.
  54. Kapuno, Raul Raymond (2008). Programming for Chemical Engineers Using C, C++, and MATLAB. Jones & Bartlett Publishers. p. 365. ISBN 978-1-934015-09-4.
  55. Herman, Russell L. (2013). A Course in Mathematical Methods for Physicists. CRC Press. p. 42. ISBN 978-1-4665-8467-9.
  56. Wouwer, Alain Vande; Saucez, Philippe; Vilas, Carlos (2014). Simulation of ODE/PDE Models with MATLAB, Octave and Scilab: Scientific and Engineering Applications. Springer. pp. 114–115. ISBN 978-3-319-06790-2.
  57. "FreeMat". freemat.sourceforge.net. Retrieved 22 February 2020.

Further reading
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