## Copyright (C) 2012 Carnë Draug
##
## 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
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn {Function File} {} iscolormap (@var{cm})
## Return true if @var{cm} is a colormap.
##
## A colormap is an @var{n} row by 3 column matrix.  The columns contain red,
## green, and blue intensities respectively.  All entries should be between 0
## and 1 inclusive.
##
## @seealso{colormap, rgbplot}
## @end deftypefn

## Author: Carnë Draug <carandraug+dev@gmail.com>

function retval = iscolormap (cm)

  if (nargin != 1)
    print_usage;
  endif

  retval = (ismatrix (cm) && isreal (cm) && isnumeric (cm) &&
            columns(cm) == 3 && ndims (cm) == 2 && isa (cm, "double") &&
            min (cm(:)) >= 0 && max (cm(:)) <= 1);

endfunction

%!assert (iscolormap (jet (64)))
%!assert (iscolormap (magic (4)), false)