From octave-sources-request at bevo dot che dot wisc dot edu Thu Nov 15 11:01:41 2001
Subject: cool and hot colormaps
From: Felipe Bertrand <fbertrand at ieee dot org>
To: octave-sources at bevo dot che dot wisc dot edu
Date: Thu, 15 Nov 2001 12:01:38 -0500


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Here are 2 functions to build the equivalent
to matlabs "cool" and "hot" colormaps.

Felipe

-- 

Felipe Bertrand
fbertrand at ieee dot org


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## Copyright (C) 1996, 1997 John W. Eaton
##
## 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 2, 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, write to the Free
## Software Foundation, 59 Temple Place - Suite 330, Boston, MA
## 02111-1307, USA.

## -*- texinfo -*-
##  at deftypefn {Function File} {} cool (@var{n})
## Create color (cyan and magenta) colormap.  
## The argument  at var{n} should be a scalar.  If it
## is omitted, 64 is assumed.
##  at end deftypefn

## Author: Tony Richardson <arichard at stark dot cc dot oh dot us>
## Created: July 1994
## Adapted-By: jwe
## Adapted-By: Felipe Bertrand

function map = cool (number)

if (nargin == 0)
  number = 64;
elseif (nargin == 1)
  if (! is_scalar (number))
    error ("cool: argument must be a scalar");
  end
else
  usage ("cool (number)");
end

dr = 1 / (number-1);
r = postpad([0:dr:1],number,1)';

g = r(number:-1:1);

b = ones(number,1);

map = [ r, g, b ];

endfunction

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## Copyright (C) 1996, 1997 John W. Eaton
##
## 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 2, 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, write to the Free
## Software Foundation, 59 Temple Place - Suite 330, Boston, MA
## 02111-1307, USA.

## -*- texinfo -*-
##  at deftypefn {Function File} {} hot (@var{n})
## Create color (black->red->yellow->white) colormap.  
## The argument  at var{n} should be a scalar.  If it
## is omitted, 64 is assumed.
##  at end deftypefn

## Author: Tony Richardson <arichard at stark dot cc dot oh dot us>
## Created: July 1994
## Adapted-By: jwe
## Adapted-By: Felipe Bertrand

function map = hot (number)

if (nargin == 0)
  number = 64;
elseif (nargin == 1)
  if (! is_scalar (number))
    error ("hot: argument must be a scalar");
  end
else
  usage ("hot (number)");
end

onethird = ceil(number/3);
twothirds = ceil(2*number/3);

dr = 1 / (onethird-1);
r = postpad([0:dr:1],number,1)';

dg = 1 / (twothirds-onethird);
g= postpad(prepad([0:dg:1],twothirds,0),number,1)';

db = 1 / (number-twothirds);
b = prepad([0:db:1],number,0)';

map = [ r, g, b ];

endfunction

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