GNU Octave
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GNU Octave 

Developed by  John W. Eaton 

Initial release  1988 
Stable release  3.0.3 (October 10, 2008) _{[+/−]} 
Preview release  3.0.1 (April 21, 2008) _{[+/−]} 
Written in  C++ 
Platform  Crossplatform 
Available in  ? 
Type  Scientific computing 
License  GNU General Public License 
Website  http://www.gnu.org/software/octave/ 
This article includes a list of references or external links, but its sources remain unclear because it lacks inline citations. Please improve this article by introducing more precise citations where appropriate. (October 2008) 
Octave is a computer program for performing numerical computations which is mostly compatible with MATLAB. It is part of the GNU Project. It is free software under the terms of the GNU General Public License.
Contents 
[edit] History
The project was conceived around 1988. At first it was intended to be a companion to a chemical reactor design course. Real development was started by John W. Eaton in 1992. The first alpha release dates back to January 4, 1993 and on February 17, 1994 version 1.0 was released. Version 3.0 was released on December 21, 2007.
It should be noted that the name has nothing to do with musical octaves. Octave is named after a former professor of the principal author, who was known for his ability to perform quick back of an envelope calculations. ^{[1]}
[edit] Technical details
 Octave is written in C++ using STL libraries.
 Octave uses an interpreter to execute the Octave language.
 Octave is extensible using dynamically loadable modules.
 Octave interpreter works in tandem with gnuplot and Grace software to create plots, graphs, and charts, and to save or print them.
[edit] 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.^{[2]} However, it does not support passing arguments by reference.^{[3]}
Octave programs consist of a list of function calls or a script. The syntax is matrixbased and provides various functions for matrix operations. It is not objectoriented, but it does support various data structures.
Its syntax is very similar to MATLAB, and carefully programming a script will allow it to run on both Octave and MATLAB.^{[4]}
Because Octave is made available under the GNU General Public License, it may be freely copied and used.^{[5]} The program runs under most Unix and Unixlike operating systems, as well as Microsoft Windows.^{[6]}
[edit] 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. For instance:
octave:1> x.a = 1; x.b = [1, 2; 3, 4]; x.c = "string"; octave:2> x.a x.a = 1 octave:3> x.b x.b = 1 2 3 4 octave:4> x.c x.c = string
 Shortcircuit boolean operators
Octave's `&&' and `' logical operators are evaluated in a shortcircuit fashion (like the corresponding operators in the C language), in contrast to the elementbyelement operators `&' and `'.
 Increment and decrement operators
Octave includes the Clike increment and decrement operators `++' and `' in both their prefix and postfix forms.
 Unwindprotect
Octave supports a limited form of exception handling modeled after the unwindprotect form of Lisp. The general form of an unwind_protect block looks like this:
unwind_protect body unwind_protect_cleanup cleanup end_unwind_protect
 Variablelength argument lists
Octave has a real 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}); endif endfunction
 Variablelength 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); endfor endfunction
 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([9000,1]):
#include <octave/oct.h> ... ColumnVector NumRands(2); NumRands(0) = 9000; 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());
[edit] MATLAB compatibility
Octave has been built with MATLAB compatibility in mind. It therefore shares many features with MATLAB:
 Matrices as fundamental data type.
 Builtin support for complex numbers.
 Powerful builtin math functions and extensive function libraries.
 Extensibility in the form of userdefined functions.
[edit] See also
[edit] External links
Wikimedia Commons has media related to: GNU Octave diagrams 
Wikibooks has a book on the topic of 
 Octave.org Home Page
[edit] Documentation
 Online documentation
 Octave wiki (click twice—page redirects cause some browsers to time out)
 Octave FAQ Wiki with new plotting commands
 Mailing List Archives on Nabble  Search all Octave mailing lists.
 Mailing List Archives on Gmane  Search all Octave mailing lists.
[edit] Graphical User Interfaces
 QtOctave Graphical User Interface  Matlab counterpart. Under heavy Development.
 Octave Workshop: an Octave IDE  Development stopped in 2006
 kOctave: Graphical User Interface  for the KDE Desktop (base for Octave Workshop) Development stopped in 2003
[edit] Web Interfaces
 Web Interface to Octave  Computing using GNU Octave in webbrowser
 Online access to Octave  Allows you to perform simple Octave calculation online.
[edit] Addons
 Octaveforge community development page  Toolboxes for various problems from independent developers.
 OctPlot  High quality 2D graphics.
 Octave graphics addon  3D visualization system for Octave.
 Octaviz  3D visualization system for Octave.
 MPI Toolbox for Octave (MPITB)  Parallel Computing for Octave using MPI.
[edit] References
 ^ Eaton, John. "About Octave". http://www.gnu.org/software/octave/about.html. Retrieved on 20081014.
 ^ "GNU Octave  Controlling subprocesses". Nov 14, 2008. http://www.networktheory.co.uk/docs/octave3/octave_269.html. Retrieved on Jan 28, 2009.
 ^ "GNU Octave". http://www.delorie.com/gnu/docs/octave/octave_105.html. Retrieved on Jan 28, 2009.
 ^ "Frequently asked questions about Octave (with answers)". http://www.gnu.org/software/octave/FAQ.html#MATLABcompatibility. Retrieved on Jan 28, 2009.
 ^ "About Octave". http://www.gnu.org/software/octave/about.html. Retrieved on Jan 28, 2009.
 ^ "Frequently asked questions about Octave (with answers)". http://www.gnu.org/software/octave/FAQ.html#GettingOctave. Retrieved on Jan 28, 2009.

