function A = digraph_adj_example_sixty ( )

%*****************************************************************************80
%
%% digraph_adj_example_sixty() sets the adjacency matrix for the sixty digraph.
%
%  Discussion:
%
%    The nodes of the digraph are divisors of 60.  There is a link from I to
%    J if divisor I can be divided by divisor J.
%
%  Licensing:
%
%    This code is distributed under the MIT license. 
%
%  Modified:
%
%    15 April 2026
%
%  Author:
%
%    John Burkardt
%
%  Output:
%
%    integer A(node_num,node_num), the adjacency information.
%    A(I,J) is 1 if there is a direct link from node I to node J.
%
  node_num = 12;
  A = zeros ( node_num, node_num );

  d = [ 60, 30, 20, 15, 12, 10, 6, 5, 4, 3, 2, 1 ];

  for i = 1 : node_num
    for j = 1 : node_num
      if ( i == j )
        A(i,j) = 0;
      elseif ( mod ( d(i), d(j) ) == 0 )
        A(i,j) = 1;
      else
        A(i,j) = 0;
      end
    end
  end

  return
end

