function a = adj2 ( )

%*****************************************************************************80
%
%% ADJ2 returns the adjacency matrix for example 2.
%
%  Discussion:
%
%    This matrix appears on page 33 of the reference.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    04 September 2015
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    John MacCormick,
%    Nine Algorithms That Changed the Future: The Ingenious Ideas that 
%    Drive Today's Computers,
%    Princeton University Press,
%    ISBN-13: 978-0691158198.
%
%  Parameters:
%
%    Output, integer A(16,16), the adjacency matrix.
%
  a = zeros ( 16, 16 );

  a(1,2) = 1.0;
  a(1,3) = 1.0;
  a(1,6) = 1.0;
  a(2,4) = 1.0;
  a(3,4) = 1.0;
  a(3,5) = 1.0;
  a(4,5) = 1.0;
  a(5,7) = 1.0;
  a(5,8) = 1.0;
  a(6,5) = 1.0;
  a(6,7) = 1.0;
  a(7,15) = 1.0;
  a(8,7) = 1.0;
  a(8,9) = 1.0;
  a(8,10) = 1.0;
  a(9,10) = 1.0;
  a(10,7) = 1.0;
  a(10,11) = 1.0;
  a(10,12) = 1.0;
  a(10,13) = 1.0;
  a(10,14) = 1.0;
  a(11,15) = 1.0;
  a(12,15) = 1.0;
  a(13,15) = 1.0;
  a(14,15) = 1.0;
  a(15,16) = 1.0;
  a(16,1) = 1.0;

  return
end
