function [ w, p ] = t_tile_word ( k )

%*****************************************************************************80
%
%% t_tile_word() returns the boundary word for a T-puzzle tile.
%
%  Discussion:
%
%    The boundary word describes how to trace the boundary by starting
%    at a base point (i,j), and taking a sequence of steps of 
%    in one of 8 directions, as suggested by this diagram:
%
%      D--C--B
%   ^  |\ | /|
%   |  | \|/ |
%   J  E--P--A
%      | /|\ |
%      |/ | \|
%      F--G--H
%
%         I-->
%
%    If the current position P has coordinates (I,J), then
%    the step of given index moves to
%
%      A  (I+1,J  )
%      B  (I+1,J+1)
%      C  (I,  J+1)
%      D  (I-1,J+1)
%      E  (I-1,J  )
%      F  (I-1,J-1)
%      G  (I,  J-1)
%      H  (I+1,J-1)
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    10 December 2021
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    integer K, a tile index.  1 <= K <= 4.
%
%  Output:
%
%    character W(WN), the boundary word.
%
%    integer P(1,2): the coordinates of the base point.
%
  p = [ 0, 0 ];

  if ( k == 1 )
    w = 'AAACCCCCCCCCFFFGGGGGG';
  elseif ( k == 2 )
    w = 'BBBBBBEEEEFFFAGGG';
  elseif ( k == 3 )
    w = 'AABBBEEEEEGGG';
  elseif ( k == 4 )
    w = 'AAACCCFFF';
  else
    fprintf ( 1, '\n' );
    fprintf ( 1, 't_tile_word(): Fatal error!\n' );
    fprintf ( 1, '  Illegal tile index %d\n', k );
    error ( 't_tile_word(): Fatal error!\n' );
  end

  return
end

