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##
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##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
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########################################################################

## -*- texinfo -*-
## @deftypefn  {} {@var{map} =} gray ()
## @deftypefnx {} {@var{map} =} gray (@var{n})
## Create gray colormap.  This colormap varies from black to white with shades
## of gray.
##
## 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: Tony Richardson <arichard@stark.cc.oh.us>
## Adapted-By: jwe

function map = gray (n)

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

endfunction


%!demo
%! ## Show the 'gray' colormap profile and as an image
%! cmap = gray (16);
%! subplot (2, 1, 1);
%!  rgbplot (cmap, "composite");
%! subplot (2, 1, 2);
%!  rgbplot (cmap);