After this discussion, in
http://en.wikibooks.org/wiki/MATLAB_Programming, as the second
paragraph, I put:
GNU Octave is a system for numerical computations with a language that
is mostly compatible with Matlab, but is available as a free software
under the GNU GPL. While a good deal of the content of this book will
also apply to Octave, it is not guaranteed to work in exactly the same
manner. Differences and comparison between MATLAB and Octave are
presented in Comparing Octave and MATLAB.
Do you agree with that formulation ?