function L = digraph_arc_sauer ( )

%*****************************************************************************80
%
%% digraph_arc_sauer() returns the arc list for the Sauer example.
%
%  Discussion:
%
%    This matrix appears on page 564 of the reference.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    25 April 2026
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Timothy Sauer,
%    Numerical Analysis,
%    Pearson, 2006,
%    ISBN: 0-321-26898-9,
%    LC: QA297.S348
%
%  Output:
%
%    integer L(34,2), the arc list.
%
  arc_num = 34;

  L = [ ...
    5,  1; ...
    1,  2; ...
    3,  2; ...
    2,  3; ...
    4,  3; ...
    8,  4; ...
    2,  5; ...
    9,  5; ...
    3,  6; ...
    9,  6; ...
    2,  7; ...
   12,  7; ...
    3,  8; ...
   12,  8; ...
    1,  9; ...
   13,  9; ...
    5, 10; ...
    6, 10; ...
    7, 10; ...
    9, 10; ...
   14, 10; ...
    6, 11; ...
    7, 11; ...
    8, 11; ...
   12, 11; ...
   14, 11; ...
    4, 12; ...
   15, 12; ...
   10, 13; ...
   14, 13; ...
   13, 14; ...
   15, 14; ...
   11, 15; ...
   14, 15 ];                     ...

  return
end

