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} =} jet ()
21 ## @deftypefnx {Function File} {@var{map} =} jet (@var{n})
22 ## Create color colormap. This colormap ranges from dark blue through blue,
23 ## cyan, green, yellow, red, to dark red.
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 = jet (n)
37 error ("jet: argument must be a scalar");
46 x = linspace(0, 1, n)';
47 r = (x >= 3/8 & x < 5/8) .* (4 * x - 3/2)\
48 + (x >= 5/8 & x < 7/8) + (x >= 7/8) .* (-4 * x + 9/2);
49 g = (x >= 1/8 & x < 3/8) .* (4 * x - 1/2)\
50 + (x >= 3/8 & x < 5/8) + (x >= 5/8 & x < 7/8) .* (-4 * x + 7/2);
51 b = (x < 1/8) .* (4 * x + 1/2) + (x >= 1/8 & x < 3/8)\
52 + (x >= 3/8 & x < 5/8) .* (-4 * x + 5/2);
61 %! ## Show the 'jet' colormap as an image
62 %! image (1:64, linspace (0, 1, 64), repmat (1:64, 64, 1)')
63 %! axis ([1, 64, 0, 1], "ticy", "xy")
64 %! colormap (jet (64))