==If I write code using Octave do I have to release it under the GPL?==
The answer depends on precisely how the code is written and how it works
Code written entirely in the scripting language of Octave (interpreted code in .m files) may be released under the terms of whatever license you choose.
Code written using Octave's native
plug-in interface (also known as a .oct file) necessarily links with Octave internals and is considered a derivative work of Octave and therefore must be released under terms that are compatible with the GPL.
Code written using Octave's implementation of the Matlab MEX interface may be released under the terms of whatever license you choose, provided that the following conditions are met:
plugin should not use any bindings that are specific to Octave . In other words, the MEX file must use the MEX interface only, and not also call on other Octave internals. It should be possible in principle to use the MEX file with other programs that implement the MEX interface (e.g., Matlab).# The MEX file should not be distributed together with Octave in such a way that they effectively create a single work. For example, you should not distribute the MEX file and Octave together in a single package such that Octave automatically loads and runs the MEX file when it starts up. There are other possible ways that you might effectively create a single work; this is just one example.
A program that embeds the Octave interpreter (e.g., by calling the "octave_main " function), or that calls functions from Octave's libraries (e.g., liboctinterp, liboctave, or libcruft) is considered a derivative work of Octave and therefore must be released under terms that are compatible with the GPL.
Since the MEX interface allows plugins to be distributed under terms that are incompatible with the GPL, does this mean that you are encouraging people to write non-free software for Octave?==
The original reason for implementing the MEX interface for Octave was to allow Octave to run free software that uses MEX files (the particular goal was to run SundialsTB in Octave). The intent was to liberate that software from Matlab and increase the amount of free software available to Octave users, not to enable people to write proprietary code for Octave . For the good of the community, we strongly encourage users of Octave to release the code they write for Octave under terms that are compatible with the GPL.
wrote a program that links with Octave libraries and I don't want to release it under the terms of the GPL . Will you change the license of the Octave libraries for me?==
Instead of asking us to change the licensing terms for Octave, we recommend that you release your program under terms that are compatible with the GPL so that the free software community can benefit from your work the same as you have benefited from the work of all the people who have contributed to Octave.
==Why can't I use code from File Exchange in Octave?
It's released under a BSD license!==
It should suffice
-- although interpretations of this vary -- to contact the author directly and have them send you the code personally, or download the code from the author's own website, if available. If you need that code or think that the code is useful, please write the authors asking them to release under a free license. Some examples of letters/email sent to authors can be found in the page [[Asking_for_package_to_be_released_under_GPL:_examples|Asking for package to be released under GPL: examples]]. Feel free to remix and reuse, just make sure you use your name!
=What's new in Octave=