function node_boundary = node_boundary_set ( nx, ny, node_num )

%% NODE_BOUNDARY_SET stores the boundary status of each node in BOUNDARY_NODE.
%
%  Discussion:
%
%    Every finite element node will is assigned an index which
%    indicates the finite element basis function and its coefficient
%    which are associated with that node.
%
%  Example:
%
%    On a simple 5 by 5 grid, where the nodes are numbered starting 
%    at the lower left, and increasing in X first, we would have the 
%    following values of NODE_BOUNDARY:
%
%       1  1  1  1  1
%       1  0  0  0  1
%       1  0  0  0  1
%       1  0  0  0  1
%       1  1  1  1  1
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    10 April 2006
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, integer NX, NY, the number of elements in the X and Y directions.
%
%    Input, integer NODE_NUM, the number of nodes.
%
%    Output, integer NODE_BOUNDARY(NODE_NUM), is
%    0, if a node is an interior node;
%    1, if a node is a Dirichlet boundary node.
%
  node = 0;

  for j = 1 : 2 * ny - 1

    for i = 1 : 2 * nx - 1

      node = node + 1;

      if ( j == 1 | ...
           j == 2 * ny - 1 | ...
           i == 1 | ...
           i == 2 * nx - 1 )
        node_boundary(node) = 1;
      else
        node_boundary(node) = 0;
      end

    end
  end

  return
end