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<h3 class="section">2.1 If I write code using Octave do I have to release it under the GPL?</h3>
<p>The answer depends on precisely how the code is written and how it works.
<p>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.
<p>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.
<p>Code written using Octave's implementation of the <span class="sc">Matlab</span> MEX
interface may be released under the terms of whatever license you
choose, provided that the following conditions are met:
<ol type=1 start=1>
<li>The 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., <span class="sc">Matlab</span>).
<li>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.
</ol>
<p>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.
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