Mercurial > octave
view scripts/image/hot.m @ 31215:5573b1d511c9
maint: Merge stable to default.
author | Markus Mützel <markus.muetzel@gmx.de> |
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date | Tue, 30 Aug 2022 11:16:55 +0200 |
parents | 796f54d4ddbf |
children | 597f3ee61a48 |
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######################################################################## ## ## Copyright (C) 1999-2022 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 {} {@var{map} =} hot () ## @deftypefnx {} {@var{map} =} hot (@var{n}) ## Create color colormap. This colormap ranges from black through dark red, ## red, orange, yellow, to white. ## ## The argument @var{n} must be a scalar. ## If unspecified, the length of the current colormap, or 64, is used. ## @seealso{colormap} ## @end deftypefn function map = hot (n) if (nargin == 1) if (! isscalar (n)) error ("hot: N must be a scalar"); endif n = double (n); else hf = get (0, "currentfigure"); if (! isempty (hf)) n = rows (get (hf, "colormap")); else n = 64; endif endif if (n == 1) map = [1, 1, 1]; elseif (n == 2) map = [1, 1, 1/2 1, 1, 1 ]; elseif (n > 2) idx = floor (3/8 * n); nel = idx; r = ones (n, 1); r(1:idx, 1) = [1:nel]' / nel; g = zeros (n, 1); g(idx+1:2*idx, 1) = r(1:idx); g(2*idx+1:end, 1) = 1; idx = 2*idx + 1; # approximately 3/4 *n nel = n - idx + 1; b = zeros (n, 1); b(idx:end, 1) = [1:nel]' / nel; map = [r, g, b]; else map = zeros (0, 3); endif endfunction %!demo %! ## Show the 'hot' colormap profile and as an image %! cmap = hot (256); %! subplot (2, 1, 1); %! rgbplot (cmap, "composite"); %! subplot (2, 1, 2); %! rgbplot (cmap);