function fem_write ( node_coord_file_name, element_file_name, ...
  node_data_file_name, dim_num, node_num, element_num, element_order, ...
  node_data_num, node_coord, element_node, node_data )

%% FEM_WRITE writes data files associated with a finite element solution.
%
%  Discussion:
%
%    This program writes the node, element and data files that define
%    a finite element geometry and data based on that geometry:
%    * a set of nodes, 
%    * a set of elements based on those nodes, 
%    * a set of data values associated with each node.
%
%  Modified:
%
%    26 January 2006
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, character NODE_COORD_FILE_NAME(*), the name of the node coordinate
%    file.  If this argument is empty, no node coordinate file will be written.
%
%    Input, character ELEMENT_FILE_NAME(*), the name of the element file.  If
%    this argument is empty, no element file will be written.
%
%    Input, character NODE_DATA_FILE_NAME(*), the name of the node data file.  If
%    this argument is empty, no node data file will be written.
%
%    Input, integer DIM_NUM, the spatial dimension.
%
%    Input, integer NODE_NUM, the number of nodes.
%
%    Input, integer ELEMENT_NUM, the number of elements.
%
%    Input, integer ELEMENT_ORDER, the order of the elements.
%
%    Input, integer NODE_DATA_NUM, the number of data items per node.
%
%    Input, real NODE_COORD(DIM_NUM,NODE_NUM), the coordinates of nodes.
%
%    Input, integer ELEMENT_NODE(ELEMENT_ORDER,ELEMENT_NUM); 
%    the global index of local node I in element J.
%
%    Input, real NODE_DATA(NODE_DATA_NUM,NODE_NUM), the data values associated
%    with each node.
%

%
%  Write the node coordinate file.
%
  if ( ~isempty ( node_coord_file_name ) & ...
    0 < s_len_trim ( node_coord_file_name ) )

    node_coord_file_unit = fopen ( node_coord_file_name, 'wt' );

    if ( node_coord_file_unit < 0 ) 
      fprintf ( 1, '\n' );
      fprintf ( 1, 'FEM_WRITE - Error!\n' );
      fprintf ( 1, '  Could not open the node coordinate file.\n' );
      error ( 'FEM_WRITE - Error!' );
      return;
    end

    r8table_header_write ( node_coord_file_name, node_coord_file_unit, ...
      dim_num, node_num );

    r8table_data_write ( node_coord_file_unit, ...
      dim_num, node_num, node_coord );

    fclose ( node_coord_file_unit );

    fprintf ( 1, '\n' );
    fprintf ( 1, 'FEM_WRITE wrote node coordinates to "%s".\n', ...
      node_coord_file_name );

  end
%
%  Write the element file.
%
  if ( ~isempty ( element_file_name ) & ...
    0 < s_len_trim ( element_file_name )  )

    element_file_unit = fopen ( element_file_name, 'wt' );

    if ( element_file_unit < 0 ) 
      fprintf ( 1, '\n' );
      fprintf ( 1, 'FEM_WRITE - Error!\n' );
      fprintf ( 1, '  Could not open the element file.\n' );
      error ( 'FEM_WRITE - Error!' );
      return;
    end

    itable_header_write ( element_file_name, element_file_unit, ...
      element_order, element_num );

    itable_data_write ( element_file_unit, ...
      element_order, element_num, element_node );

    fclose ( element_file_unit );

    fprintf ( 1, '\n' );
    fprintf ( 1, 'FEM_WRITE wrote element data to "%s".\n', ...
      element_file_name );

  end
%
%  Write the node data file.
%
  if ( ~isempty ( node_data_file_name ) & ...
    0 < s_len_trim ( node_data_file_name ) )

    node_data_file_unit = fopen ( node_data_file_name, 'wt' );

    if ( node_data_file_unit < 0 ) 
      fprintf ( 1, '\n' );
      fprintf ( 1, 'FEM_WRITE - Error!\n' );
      fprintf ( 1, '  Could not open the node data file.\n' );
      error ( 'FEM_WRITE - Error!' );
      return;
    end

    r8table_header_write ( node_data_file_name, node_data_file_unit, ...
      node_data_num, node_num );

    r8rtable_data_write ( node_data_file_unit, ...
      node_data_num, node_num, node_data );

    fclose ( node_data_file_unit );

    fprintf ( 1, '\n' );
    fprintf ( 1, 'FEM_WRITE wrote node data to "%s".\n', ...
      node_data_file_name );

  end