To cite GNU Octave in publications use:

  John W. Eaton, David Bateman, Søren Hauberg, Rik Wehbring (2015).
  GNU Octave version 4.0.0 manual: a high-level interactive language for
  numerical computations.
  URL http://www.gnu.org/software/octave/doc/interpreter/

A BibTeX entry for LaTeX users is:

  @book{,
    author    = {John W. Eaton, David Bateman, S\oren Hauberg, and Rik Wehbring},
    title     = {{GNU Octave} version 4.0.0 manual: a high-level interactive language for numerical computations},
    year      = {2015},
    url       = {http://www.gnu.org/software/octave/doc/interpreter},
  }

We have invested a lot of time and effort in creating GNU Octave, please cite it
when using it.  See also `citation pkgname' for citing Octave packages.