Octave is also free software; you can redistribute it and/or modify it under the terms of the GNU General Public License, version 3, as published by the Free Software Foundation, or at your option any later version.
==Why are the developers planning to replace Gnuplot with an OpenGL backend?==
The development of Octave is committed to being both compatible with Matlab and adding additional features. Toward those ends, the development community has chosen to introduce a native OpenGL backend that supports Matlab handle graphics and its uicontrols. Starting with the 3.8 release, Octave now uses OpenGL graphics by default with FLTK widgets. A Qt OpenGL toolkit is also [https://github.com/goffioul/QtHandles under development].
There are no plans to remove the gnuplot backend. While a better backend may some day become the new default plotter, the gnuplot backend will still be available as long as our users find it useful.
== How can I cite Octave? ==
made it free software so we could reuse large chunks of it which were
incorporated in what is now the Octave GUI.