## Copyright (C) 1999-2020 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this distribution
## or <https://octave.org/COPYRIGHT.html/>.
##
##
## This file is part of Octave.
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## under the terms of the GNU General Public License as published by
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## (at your option) any later version.
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## -*- texinfo -*-
## @deftypefn  {} {@var{map} =} winter ()
## @deftypefnx {} {@var{map} =} winter (@var{n})
## Create color colormap.  This colormap varies from blue to green.
##
## The argument @var{n} must be a scalar.
## If unspecified, the length of the current colormap, or 64, is used.
## @seealso{colormap}
## @end deftypefn

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

function map = winter (n)

  if (nargin > 1)
    print_usage ();
  elseif (nargin == 1)
    if (! isscalar (n))
      error ("winter: 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 = [0, 0, 1];
  elseif (n > 1)
    r = zeros (n, 1);
    g = [0:(n-1)]' / (n - 1);
    b = 1 - g / 2;
    map = [r, g, b];
  else
    map = zeros (0, 3);
  endif

endfunction


%!demo
%! ## Show the 'winter' colormap profile and as an image
%! cmap = winter (256);
%! subplot (2, 1, 1);
%!  rgbplot (cmap, "composite");
%! subplot (2, 1, 2);
%!  rgbplot (cmap);