function solution_write ( node_num, node_u, output_filename )

%% SOLUTION_WRITE writes the solution to a file.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    05 June 2004
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, integer NODE_NUM, the number of nodes.
%
%    Input, real NODE_U(NODE_NUM), the coefficients of
%    the solution.
%
%    Input, character ( len = * ) OUTPUT_FILENAME, the name of the file
%    in which the data should be stored.
%
  output_unit = fopen ( output_filename, 'wt');

  if ( output_unit < 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'SOLUTION_WRITE - Warning!\n' );
    fprintf ( 1, '  Could not write the solution file.\n' );
    return;
  end

  for node = 1 : node_num

    fprintf ( output_unit, '%14f\n', node_u(node) );

  end

  fclose ( output_unit );

  return
end