########################################################################
##
## Copyright (C) 2013-2026 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## This file is part of Octave.
##
## Octave is free software: you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## Octave is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING.  If not, see
## <https://www.gnu.org/licenses/>.
##
########################################################################

## -*- texinfo -*-
## @deftypefn  {} {} citation
## @deftypefnx {} {} citation @var{package}
## Display instructions for citing GNU Octave or its packages in publications.
##
## When called without an argument, display information on how to cite the core
## GNU Octave system.
##
## When given a package name @var{package}, display information on citing the
## specific named package.  Note that some packages may not yet have
## instructions on how to cite them.
##
## The GNU Octave developers and its active community of package authors have
## invested a lot of time and effort in creating GNU Octave as it is today.
## Please give credit where credit is due and cite GNU Octave and its packages
## when you use them.
##
## @end deftypefn

## Author: Carnë Draug <carandraug+dev@gmail.com>
## Idea and documentation from R's citation() (also under GPL)

function citation (package = "octave")

  ## function takes care of validating PACKAGE input
  display_info_file ("citation", package, "CITATION");

endfunction


## Test input validation
%!error <citation: PACKAGE must be a string> citation (1)
%!error <citation: package .* is not installed>
%! citation ("__NOT_A_VALID_PKG_NAME__");
