function wathen_spy_test ( )

%*****************************************************************************80
%
%% wathen_spy_test() uses spy() to display the sparsity of the Wathen matrix.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    27 September 2022
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'wathen_spy_test\n' );
  fprintf ( 1, '  Use spy() to display the sparsity of the Wathen matrix.\n' );

  clf ( );

  for k = 1 : 6
    subplot ( 2, 3, k );
    nx = k;
    ny = k;
    n = wathen_order ( nx, ny );
    a = wathen_davis ( nx, ny, n );
    spy ( a );
  end
%
%  "suptitle" not available in Octave!
%  Hell, it's not even available in MATLAB!
%
  if ( false )
% if ( ~ is_octave ( ) )
    suptitle ( 'WATHEN Matrix Sparsity Pattern' );
  end

  filename = 'wathen_spy.png';
  print ( '-dpng', filename );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Graphics file saved as "%s"\n', filename );

  return
end

