1 ## Copyright (C) 1999-2012 Kai Habel
3 ## This file is part of Octave.
5 ## Octave is free software; you can redistribute it and/or modify it
6 ## under the terms of the GNU General Public License as published by
7 ## the Free Software Foundation; either version 3 of the License, or (at
8 ## your option) any later version.
10 ## Octave is distributed in the hope that it will be useful, but
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 ## General Public License for more details.
15 ## You should have received a copy of the GNU General Public License
16 ## along with Octave; see the file COPYING. If not, see
17 ## <http://www.gnu.org/licenses/>.
20 ## @deftypefn {Function File} {@var{map} =} prism ()
21 ## @deftypefnx {Function File} {@var{map} =} prism (@var{n})
22 ## Create color colormap. This colormap cycles through red, orange, yellow,
23 ## green, blue and violet with each index change.
24 ## The argument @var{n} must be a scalar.
25 ## If unspecified, the length of the current colormap, or 64, is used.
29 ## Author: Kai Habel <kai.habel@gmx.de>
31 function map = prism (n)
37 error ("prism: argument must be a scalar");
43 p = [1, 0, 0; 1, 1/2, 0; 1, 1, 0; 0, 1, 0; 0, 0, 1; 2/3, 0, 1];
46 map = kron(ones (fix (n / 6), 1), p);
48 map = [kron(ones (fix (n / 6), 1), p); p(1:rem (n, 6), :)];
54 %! ## Show the 'prism' colormap as an image
55 %! image (1:64, linspace (0, 1, 64), repmat (1:64, 64, 1)')
56 %! axis ([1, 64, 0, 1], "ticy", "xy")
57 %! colormap (prism (64))