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} =} hot ()
21 ## @deftypefnx {Function File} {@var{map} =} hot (@var{n})
22 ## Create color colormap. This colormap ranges from black through dark red,
23 ## red, orange, yellow, to white.
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 = hot (n)
37 error ("hot: argument must be a scalar");
46 x = linspace (0, 1, n)';
47 r = (x < 2/5) .* (5/2 * x) + (x >= 2/5);
48 g = (x >= 2/5 & x < 4/5) .* (5/2 * x - 1) + (x >= 4/5);
49 b = (x >= 4/5) .* (5*x - 4);
58 %! ## Show the 'hot' colormap as an image
59 %! image (1:64, linspace (0, 1, 64), repmat (1:64, 64, 1)')
60 %! axis ([1, 64, 0, 1], "ticy", "xy")
61 %! colormap (hot (64))