Editing GNU Octave (section)

=={{anchor|MATLAB}} MATLAB compatibility==
Octave has been built with MATLAB compatibility in mind, and shares many features with MATLAB:

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

Octave treats incompatibility with MATLAB as a [[Bug (software)|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 [[License compatibility|compatible]] and proper [[open-source license|open source]] [[BSD license]], the FileExchange [[EULA|Terms of use]] prohibit any usage beside MathWorks' [[proprietary software|proprietary]] MATLAB.<ref>{{Cite web |title=FAQ - Octave |url=https://wiki.octave.org/FAQ |access-date=2022-12-05 |website=wiki.octave.org}}</ref><ref>{{Cite web |title=MATLAB Central Terms of Use |url=https://www.mathworks.com/matlabcentral/content/terms-of-use.html |access-date=2022-12-05 |website=www.mathworks.com |language=en}}</ref><ref>{{Cite web |title=File Exchange Licensing FAQ |url=https://www.mathworks.com/matlabcentral/content/fx/fx-transition-faq.html |access-date=2022-12-05 |website=www.mathworks.com |language=en}}</ref>

===Syntax compatibility===
There are a few purposeful, albeit minor, [http://octave.org/wiki/index.php?title=FAQ#Porting_programs_from_Matlab_to_Octave syntax additions] {{Webarchive|url=https://web.archive.org/web/20120426060857/http://octave.org/wiki/index.php?title=FAQ#Porting_programs_from_Matlab_to_Octave |date=2012-04-26 }}:

# [[Comment (computer programming)|Comment]] lines can be prefixed with the # character as well as the % character;
# Various [[C (programming language)|C-based]] operators [[Increment operator|++]], [[Decrement operator|--]], [[Augmented assignment|+=]], *=, /= are supported;
# Elements can be referenced without creating a new variable by cascaded indexing, e.g. [1:10](3);
# [[String (computer science)|String]]s can be defined with the double-quote " character as well as the single-quote ' character;
# When the variable type is [[Single-precision floating-point format|single]] (a single-precision floating-point number), Octave calculates the "[[mean]]" in the single-domain (MATLAB in [[Double-precision floating-point format|double-domain]]) which is faster but gives less accurate results;
# Blocks can also be terminated with more specific [[Control structure]] keywords, i.e., endif, endfor, endwhile, etc.;
# Functions can be defined within scripts and at the Octave prompt;
# Presence of a do-until loop (similar to [[Do while loop|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 [https://octave.sourceforge.io Octave Forge]. The functions available as part of either core Octave or Forge packages are listed [https://octave.sourceforge.io/list_functions.php?q=&sort=alphabetic online] {{Webarchive|url=https://web.archive.org/web/20240314051049/https://octave.sourceforge.io/list_functions.php?q=&sort=alphabetic |date=2024-03-14 }}.

A list of unavailable functions is included in the Octave function  [http://hg.savannah.gnu.org/hgweb/octave/file/tip/scripts/help/__unimplemented__.m <code>__unimplemented.m__</code>]. Unimplemented functions are also listed under many Octave Forge packages in the [https://wiki.octave.org/Category:Octave_Forge Octave Wiki].

When an unimplemented function is called the following error message is shown:
<syntaxhighlight lang="octave">
  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
</syntaxhighlight>