## Copyright (C) 1999,2000  Kai Habel
##
## This program 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 of the License, or
## (at your option) any later version.
##
## This program 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 this program; if not, write to the Free Software
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

## -*- texinfo -*-
## @deftypefn {Function File} {} bone (@var{n})
## Create color colormap. 
## (a gray colormap with a light blue tone)
## The argument @var{n} should be a scalar.  If it
## is omitted, the length of the current colormap or 64 is assumed.
## @end deftypefn
## @seealso{colormap}

## Author:  Kai Habel <kai.habel@gmx.de>

function map = bone (number)

  global __current_color_map__

  if (nargin == 0)
    if exist ("__current_color_map__")
      number = rows (__current_color_map__);
    else
      number = 64;
    endif
  elseif (nargin == 1)
    if (! is_scalar (number))
      error ("bone: argument must be a scalar");
    endif
  else
    usage ("bone (number)");
  endif
  # for matlab compatibility
  map = [];
  if (number == 1)
    map = [0, 0, 0];  
  elseif (number > 1)
    x = linspace (0, 1, number)';

    r = (x < 3/4) .* (7/8 * x) + (x >= 3/4) .* (11/8 * x - 3/8);
    g = (x < 3/8) .* (7/8 * x)\
      + (x >= 3/8 & x < 3/4) .* (29/24 * x - 1/8)\
      + (x >= 3/4) .* (7/8 * x + 1/8);
    b = (x < 3/8) .* (29/24 * x) + (x >= 3/8) .* (7/8 * x + 1/8);
    map=[r, g, b];
  endif
endfunction