function triangulation_plot ( prefix, node_show, triangle_show )

%*****************************************************************************80
%
%% TRIANGULATION_PLOT is the main program.
%
%  Discussion:
%
%    TRIANGULATION_PLOT plots a triangulated set of nodes.
%
%  Usage:
%
%    triangulation_plot prefix node_vis triangle_vis
%
%    where:
%
%    'prefix' is the common prefix for the node and triangle files:
%
%    * prefix_nodes.txt,     the node coordinates.
%    * prefix_elements.txt,  the nodes that make up each triangle.
%    * prefix.eps, the plot of the triangulation.
%
%    'node_vis' indicates the node visibility:
%
%    0: do not show the nodes;
%    1:        show the nodes;
%    2:        show the nodes, and label them.
%
%    'triangle_vis' indicates the triangle visibility:
%
%    0: do not show the triangles;
%    1:        show the triangles;
%    2:        show the triangles, and label them.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    04 October 2009
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  timestamp ( );

  fprintf ( 1, '\n' );
  fprintf ( 1, 'TRIANGULATION_PLOT\n' );
  fprintf ( 1, '  MATLAB version\n' );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Read a node dataset of NODE_NUM points in 2 dimensions.\n' );
  fprintf ( 1, '  Read an associated triangulation dataset of TRIANGLE_NUM\n' );
  fprintf ( 1, '  triangles using 3, 4 or 6 nodes.\n' );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Make an EPS plot of the triangulated data.\n' );
%
%  First argument is the file prefix.
%
  if ( nargin < 1 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'TRIANGULATION_PLOT:\n' );
    prefix = input ( '  Enter the file prefix' );
  end
%
%  Second argument is node visibility.
%
  if ( nargin < 2 )
    fprintf ( 1, '\n' );
    fprintf ( 1, '  Options for node visibility:\n' );
    fprintf ( 1, '  0: do not show the nodes;\n' );
    fprintf ( 1, '  1:        show the nodes;\n' );
    fprintf ( 1, '  2:        show the nodes, and label them.\n' );
    node_show = input ( '  Enter the node visibility option:' );
  end
%
%  Third argument is triangle visibility.
%
  if ( nargin < 3 )
    fprintf ( 1, '\n' );
    fprintf ( 1, '  Options for triangle visibility:\n' );
    fprintf ( 1, '  0: do not show the triangles;\n' );
    fprintf ( 1, '  1:        show the triangles;\n' );
    fprintf ( 1, '  2:        show the triangles, and label them.\n' );
    triangle_show = input ( '  Enter the triangle visibility option:' );
  end
%
%  Create the file names.
%
  node_filename = strcat ( prefix, '_nodes.txt' );
  element_filename = strcat ( prefix, '_elements.txt' );
  plot_filename = strcat ( prefix, '.eps' );
%
%  Read the node data.
%
  [ dim_num, node_num ] = r8mat_header_read ( node_filename );

  fprintf ( 1, '\n' );
  fprintf ( 1, '  Read the header of "%s".\n', node_filename );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Spatial dimension DIM_NUM = %d\n', dim_num );
  fprintf ( 1, '  Number of nodes NODE_NUM  = %d\n', node_num );

  node_xy = r8mat_data_read ( node_filename, dim_num, node_num );

  fprintf ( 1, '\n' );
  fprintf ( 1, '  Read the data in "%s".\n', node_filename );

  r8mat_transpose_print_some ( dim_num, node_num, node_xy, 1, 1, 2, 5, ...
    '  Initial portion of data read from file:' );
%
%  Read the element data.
%
  [ triangle_order, triangle_num ] = i4mat_header_read ( element_filename );

  fprintf ( 1, '\n' );
  fprintf ( 1, '  Read the header of "%s".\n', element_filename );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Triangle order TRIANGLE_ORDER     = %d\n', triangle_order );
  fprintf ( 1, '  Number of triangles TRIANGLE_NUM  = %d\n', triangle_num );

  triangle_node = i4mat_data_read ( element_filename, ...
    triangle_order, triangle_num );

  fprintf ( 1, '\n' );
  fprintf ( 1, '  Read the data in "%s".\n', element_filename );

  i4mat_transpose_print_some ( triangle_order, triangle_num, triangle_node, ...
    1, 1, triangle_order, 5, '  Initial portion of data read from file:' );
%
%  Detect and correct 0-based indexing.
%
  triangle_node = mesh_base_one ( node_num, triangle_order, triangle_num, ...
    triangle_node );
%
%  Create the output file.
%
  if ( triangle_order == 3 )

    triangulation_order3_plot ( plot_filename, node_num, node_xy, ...
      triangle_num, triangle_node, node_show, triangle_show );

  elseif ( triangle_order == 4 )

    triangulation_order4_plot ( plot_filename, node_num, node_xy, ...
      triangle_num, triangle_node, node_show, triangle_show );

  elseif ( triangle_order == 6 )

    triangulation_order6_plot ( plot_filename, node_num, node_xy, ...
      triangle_num, triangle_node, node_show, triangle_show );

  end

  fprintf ( 1, '\n' );
  fprintf ( 1, '  Created the EPS file "%s".\n', plot_filename );

  fprintf ( 1, '\n' );
  fprintf ( 1, 'TRIANGULATION_PLOT\n' );
  fprintf ( 1, '  Normal end of execution.\n' );

  fprintf ( 1, '\n' );
  timestamp ( );

  return
end
function column_num = file_column_count ( input_file_name )

%*****************************************************************************80
%
%% FILE_COLUMN_COUNT counts the columns in the first line of a file.
%
%  Discussion:
%
%    The file is assumed to be a simple text file.
%
%    Most lines of the file are presumed to consist of COLUMN_NUM words,
%    separated by spaces.  There may also be some blank lines, and some 
%    comment lines, which have a "#" in column 1.
%
%    The routine tries to find the first non-comment non-blank line and
%    counts the number of words in that line.
%
%    If all lines are blanks or comments, it goes back and tries to analyze
%    a comment line.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license. 
%
%  Modified:
%
%    21 February 2004
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILE_NAME, the name of the file.
%
%    Output, integer COLUMN_NUM, the number of columns in the file.
%
  FALSE = 0;
  TRUE = 1;
%
%  Open the file.
%
  input_unit = fopen ( input_file_name );

  if ( input_unit < 0 ) 
    fprintf ( 1, '\n' );
    fprintf ( 1, 'FILE_COLUMN_COUNT - Error!\n' );
    fprintf ( 1, '  Could not open the file "%s".\n', input_file_name );
    error ( 'FILE_COLUMN_COUNT - Error!' );
    column_num = -1;
    return;
  end
%
%  Read one line, but skip blank lines and comment lines.
%  Use FGETL so we drop the newline character!
%
  got_one = FALSE;

  while ( 1 )

    line = fgetl ( input_unit );

    if ( line == -1 )
      break;
    end

    if ( s_len_trim ( line ) == 0 )

    elseif ( line(1) == '#' )

    else
      got_one = TRUE;
      break;
    end

  end

  fclose ( input_unit );

  if ( got_one == FALSE ) 
    fprintf ( 1, '\n' );
    fprintf ( 1, 'FILE_COLUMN_COUNT - Warning!\n' );
    fprintf ( 1, '  The file does not seem to contain any data.\n' );
    column_num = -1;
    return;
  end

  column_num = s_word_count ( line );

  return
end
function row_num = file_row_count ( input_file_name )

%*****************************************************************************80
%
%% FILE_ROW_COUNT counts the number of row records in a file.
%
%  Discussion:
%
%    Each input line is a "RECORD".
%
%    The records are divided into three groups:
%    
%    * BLANK LINES (nothing but blanks)
%    * COMMENT LINES (begin with a '#')
%    * DATA RECORDS (anything else)
%
%    The value returned by the function is the number of data records.
%
%    By the way, if the MATLAB routine FGETS is used, instead of
%    FGETL, then the variable LINE will include line termination 
%    characters, which means that a blank line would not actually
%    have zero characters.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license. 
%
%  Modified:
%
%    31 December 2006
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILE_NAME, the name of the input file.
%
%    Output, integer ROW_NUM, the number of rows found. 
%
  input_unit = fopen ( input_file_name );

  if ( input_unit < 0 ) 
    fprintf ( 1, '\n' );
    fprintf ( 1, 'FILE_ROW_COUNT - Error!\n' );
    fprintf ( 1, '  Could not open the file "%s".\n', input_file_name );
    error ( 'FILE_ROW_COUNT - Error!' );
    row_num = -1;
    return;
  end

  blank_num = 0;
  comment_num = 0;
  row_num = 0;
  
  record_num = 0;

  while ( 1 )

    line = fgetl ( input_unit );

    if ( line == -1 )
      break;
    end

    record_num = record_num + 1;
    record_length = s_len_trim ( line );
    
    if ( record_length <= 0 )
      blank_num = blank_num + 1;
    elseif ( line(1) == '#' )
      comment_num = comment_num + 1;
    else
      row_num = row_num + 1;
    end

  end

  fclose ( input_unit );

  return
end
function table = i4mat_data_read ( input_filename, m, n )

%*****************************************************************************80
%
%% I4MAT_DATA_READ reads data from an I4MAT file.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    27 January 2006
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILENAME, the name of the input file.
%
%    Input, integer M, N, the number of rows and columns in the data.
%
%    Output, integer TABLE(M,N), the point coordinates.
%
  table = [];
%
%  Build up the format string for reading M real numbers.
%
  string = ' ';

  for i = 0 : m
    string = strcat ( string, ' %d' );
  end

  input_unit = fopen ( input_filename );

  if ( input_unit < 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'I4MAT_DATA_READ - Error!\n' );
    fprintf ( 1, '  Could not open the input file.\n' );
    error ( 'I4MAT_DATA_READ - Error!' );
    return;
  end

  i = 0;

  while ( i < n )

    line = fgets ( input_unit );

    if ( line == -1 )
      fprintf ( 1, '\n' );
      fprintf ( 1, 'I4MAT_DATA_READ - Error!\n' );
      fprintf ( 1, '  End of input while reading data.\n' );
      error ( 'I4MAT_DATA_READ - Error!' );
    end

    if ( line(1) == '#' )

    elseif ( s_len_trim ( line ) == 0 )
      
    else

      [ x, count ] = sscanf ( line, string );

      if ( count == m )
        i = i + 1;
        table(1:m,i) = x(1:m);
      end

    end

  end

  fclose ( input_unit );

  return
end
function [ m, n ] = i4mat_header_read ( input_filename )

%*****************************************************************************80
%
%% I4MAT_HEADER_READ reads the header from an I4MAT file.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    22 October 2004
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILENAME, the name of the input file.
%
%    Output, integer M, the spatial dimension.
%
%    Output, integer N, the number of points.
%
  m = file_column_count ( input_filename );

  if ( m <= 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'I4MAT_HEADER_READ - Fatal error!\n' );
    fprintf ( 1, '  There was some kind of I/O problem while trying\n' );
    fprintf ( 1, '  to count the number of data columns in\n' );
    fprintf ( 1, '  the file %s.\n', input_filename );
  end

  n = file_row_count ( input_filename );

  if ( n <= 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'I4MAT_HEADER_READ - Fatal error!\n' );
    fprintf ( 1, '  There was some kind of I/O problem while trying\n' );
    fprintf ( 1, '  to count the number of data rows in\n' );
    fprintf ( 1, '  the file %s\n', input_filename );
  end

  return
end
function i4mat_transpose_print_some ( m, n, a, ilo, jlo, ihi, jhi, title )

%*****************************************************************************80
%
%% I4MAT_TRANSPOSE_PRINT_SOME prints some of an I4MAT, transposed.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    21 June 2005
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, integer M, N, the number of rows and columns.
%
%    Input, integer A(M,N), an M by N matrix to be printed.
%
%    Input, integer ILO, JLO, the first row and column to print.
%
%    Input, integer IHI, JHI, the last row and column to print.
%
%    Input, string TITLE, an optional title.
%
  incx = 10;

  if ( 0 < s_len_trim ( title ) )
    fprintf ( 1, '\n' );
    fprintf ( 1, '%s\n', title );
  end

  for i2lo = max ( ilo, 1 ) : incx : min ( ihi, m )

    i2hi = i2lo + incx - 1;
    i2hi = min ( i2hi, m );
    i2hi = min ( i2hi, ihi );

    inc = i2hi + 1 - i2lo;

    fprintf ( 1, '\n' );
    fprintf ( 1, '  Row: ' );
    for i = i2lo : i2hi
      fprintf ( 1, '%7d  ', i );
    end
    fprintf ( 1, '\n' );
    fprintf ( 1, '  Col\n' );
    fprintf ( 1, '\n' );

    j2lo = max ( jlo, 1 );
    j2hi = min ( jhi, n );

    for j = j2lo : j2hi

      fprintf ( 1, '%5d  ', j );
      for i2 = 1 : inc
        i = i2lo - 1 + i2;
        fprintf ( 1, '%7d  ', a(i,j) );
      end
      fprintf ( 1, '\n' );

    end

  end

  return
end
function element_node = mesh_base_one ( node_num, element_order, ...
  element_num, element_node )

%*****************************************************************************80
%
%% MESH_BASE_ONE ensures that the element definition is one-based.
%
%  Discussion:
%
%    The ELEMENT_NODE array contains nodes indices that form elements.
%    The convention for node indexing might start at 0 or at 1.
%    Since a MATLAB program will naturally assume a 1-based indexing, it is
%    necessary to check a given element definition and, if it is actually
%    0-based, to convert it.
%
%    This function attempts to detect 0-based node indexing and correct it.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license. 
%
%  Modified:
%
%    29 September 2009
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, integer NODE_NUM, the number of nodes.
%
%    Input, integer ELEMENT_ORDER, the order of the elements.
%
%    Input, integer ELEMENT_NUM, the number of elements.
%
%    Input/output, integer ELEMENT_NODE(ELEMENT_ORDE,ELEMENT_NUM), the element
%    definitions.
%
  node_min = min ( min ( element_node(1:element_order,1:element_num) ) );
  node_max = max ( max ( element_node(1:element_order,1:element_num) ) );

  if ( node_min == 0 & node_max == node_num - 1 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'MESH_BASE_ONE:\n' );
    fprintf ( 1, '  The element indexing appears to be 0-based!\n' );
    fprintf ( 1, '  This will be converted to 1-based.\n' );
    element_node(1:element_order,1:element_num) = ...
      element_node(1:element_order,1:element_num) - 1;
  elseif ( node_min == 1 & node_max == node_num )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'MESH_BASE_ONE:\n' );
    fprintf ( 1, '  The element indexing appears to be 1-based!\n' );
    fprintf ( 1, '  No conversion is necessary.\n' );
  else
    fprintf ( 1, '\n' );
    fprintf ( 1, 'MESH_BASE_ONE - Warning!\n' );
    fprintf ( 1, '  The element indexing is not of a recognized type.\n' );
    fprintf ( 1, '  NODE_MIN = %d\n', node_min );
    fprintf ( 1, '  NODE_MAX = %d\n', node_max );
    fprintf ( 1, '  NODE_NUM = %d\n', node_num );
  end

  return
end
function table = r8mat_data_read ( input_filename, m, n )

%*****************************************************************************80
%
%% R8MAT_DATA_READ reads data from an R8MAT file.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    27 January 2006
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILENAME, the name of the input file.
%
%    Input, integer M, N, the number of rows and columns of data.
%
%    Output, real TABLE(M,N), the point coordinates.
%
  table = [];
%
%  Build up the format string for reading M real numbers.
%
  string = ' ';

  for i = 0 : m
    string = strcat ( string, ' %f' );
  end

  input_unit = fopen ( input_filename );

  if ( input_unit < 0 ) 
    fprintf ( 1, '\n' );
    fprintf ( 1, 'R8MAT_DATA_READ - Error!\n' );
    fprintf ( 1, '  Could not open the file.\n' );
    error ( 'R8MAT_DATA_READ - Error!' );
    return;
  end

  i = 0;

  while ( i < n )

    line = fgets ( input_unit );

    if ( line == -1 )
      break;
    end

    if ( line(1) == '#' )

    elseif ( s_len_trim ( line ) == 0 )
      
    else

      [ x, count ] = sscanf ( line, string );

      if ( count == m )
        i = i + 1;
        table(1:m,i) = x(1:m);
      end

    end

  end

  fclose ( input_unit );

  return
end
function [ m, n ] = r8mat_header_read ( input_filename )

%*****************************************************************************80
%
%% R8MAT_HEADER_READ reads the header from an R8MAT file.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    22 October 2004
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string INPUT_FILENAME, the name of the input file.
%
%    Output, integer M, the spatial dimension.
%
%    Output, integer N, the number of points.
%
  m = file_column_count ( input_filename );

  if ( m <= 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'R8MAT_HEADER_READ - Fatal error!\n' );
    fprintf ( 1, '  There was some kind of I/O problem while trying\n' );
    fprintf ( 1, '  to count the number of data columns in\n' );
    fprintf ( 1, '  the file %s.\n', input_filename );
  end

  n = file_row_count ( input_filename );

  if ( n <= 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'R8MAT_HEADER_READ - Fatal error!\n' );
    fprintf ( 1, '  There was some kind of I/O problem while trying\n' );
    fprintf ( 1, '  to count the number of data rows in\n' );
    fprintf ( 1, '  the file %s\n', input_filename );
  end

  return
end
function r8mat_transpose_print_some ( m, n, a, ilo, jlo, ihi, jhi, title )

%*****************************************************************************80
%
%% R8MAT_TRANSPOSE_PRINT_SOME prints some of an R8MAT, transposed.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    23 May 2005
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, integer M, N, the number of rows and columns.
%
%    Input, real A(M,N), an M by N matrix to be printed.
%
%    Input, integer ILO, JLO, the first row and column to print.
%
%    Input, integer IHI, JHI, the last row and column to print.
%
%    Input, string TITLE, an optional title.
%
  incx = 5;

  if ( 0 < s_len_trim ( title ) )
    fprintf ( 1, '\n' );
    fprintf ( 1, '%s\n', title );
  end

  for i2lo = max ( ilo, 1 ) : incx : min ( ihi, m )

    i2hi = i2lo + incx - 1;
    i2hi = min ( i2hi, m );
    i2hi = min ( i2hi, ihi );

    inc = i2hi + 1 - i2lo;
    
    fprintf ( 1, '\n' );
    fprintf ( 1, '  Row: ' );
    for i = i2lo : i2hi
      fprintf ( 1, '%7d       ', i );
    end
    fprintf ( 1, '\n' );
    fprintf ( 1, '  Col\n' );

    j2lo = max ( jlo, 1 );
    j2hi = min ( jhi, n );

    for j = j2lo : j2hi

      fprintf ( 1, '%5d ', j );
      for i2 = 1 : inc
        i = i2lo - 1 + i2;
        fprintf ( 1, '%12f', a(i,j) );
      end
      fprintf ( 1, '\n' );

    end

  end

  return
end
function len = s_len_trim ( s )

%*****************************************************************************80
%
%% S_LEN_TRIM returns the length of a character string to the last nonblank.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    14 June 2003
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string S, the string to be measured.
%
%    Output, integer LEN, the length of the string up to the last nonblank.
%
  len = length ( s );

  while ( 0 < len )
    if ( s(len) ~= ' ' )
      return
    end
    len = len - 1;
  end

  return
end
function word_num = s_word_count ( s )

%*****************************************************************************80
%
%% S_WORD_COUNT counts the number of "words" in a string.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    30 January 2006
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string S, the string to be examined.
%
%    Output, integer WORD_NUM, the number of "words" in the string.
%    Words are presumed to be separated by one or more blanks.
%
  FALSE = 0;
  TRUE = 1;

  word_num = 0;
  s_length = length ( s );

  if ( s_length <= 0 )
    return;
  end

  blank = TRUE;

  for i = 1 : s_length

    if ( s(i) == ' ' )
      blank = TRUE;
    elseif ( blank == TRUE )
      word_num = word_num + 1;
      blank = FALSE;
    end

  end

  return
end
function timestamp ( )

%*****************************************************************************80
%
%% TIMESTAMP prints the current YMDHMS date as a timestamp.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    14 February 2003
%
%  Author:
%
%    John Burkardt
%
  t = now;
  c = datevec ( t );
  s = datestr ( c, 0 );
  fprintf ( 1, '%s\n', s );

  return
end
function s = timestring ( )

%*****************************************************************************80
%
%% TIMESTRING returns a string containing the current YMDHMS date.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    07 August 2003
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Output, string S, a string containing the current YMDHMS date.
%
  t = now;
  c = datevec ( t );
  s = datestr ( c, 0 );

  return
end
function triangulation_order3_plot ( file_name, node_num, node_xy, ...
  triangle_num, triangle_node, node_show, triangle_show )

%*****************************************************************************80
%
%% TRIANGULATION_ORDER3_PLOT plots a 3-node triangulation of a pointset.
%
%  Discussion:
%
%    The triangulation is most usually a Delaunay triangulation,
%    but this is not necessary.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    08 June 2009
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string FILE_NAME, the name of the output file.
%
%    Input, integer NODE_NUM, the number of points.
%
%    Input, real NODE_XY(2,NODE_NUM), the nodes.
%
%    Input, integer TRIANGLE_NUM, the number of triangles.
%
%    Input, integer TRIANGLE_NODE(3,TRIANGLE_NUM), lists, for each triangle,
%    the indices of the points that form the vertices of the triangle.
%
%    Input, logical NODE_SHOW:
%    0, do not show the nodes.
%    1, show the nodes.
%    2, show the nodes, and label them.
%
%    Input, logical TRIANGLE_SHOW, 
%    0, do not show the triangles.
%    1, show the triangles.
%    2, show the triangles, and label them.
%
  x_ps_max = 576;
  x_ps_max_clip = 594;
  x_ps_min = 36;
  x_ps_min_clip = 18;
  y_ps_max = 666;
  y_ps_max_clip = 684;
  y_ps_min = 126;
  y_ps_min_clip = 108;

  date_time = timestring ( );
%
%  We need to do some figuring here, so that we can determine
%  the range of the data, and hence the height and width
%  of the piece of paper.
%
  x_max = max ( node_xy(1,1:node_num) );
  x_min = min ( node_xy(1,1:node_num) );
  x_scale = x_max - x_min;
  
  x_max = x_max + 0.05 * x_scale;
  x_min = x_min - 0.05 * x_scale;
  x_scale = x_max - x_min;

  y_max = max ( node_xy(2,1:node_num) );
  y_min = min ( node_xy(2,1:node_num) );
  y_scale = y_max - y_min;

  y_max = y_max + 0.05 * y_scale;
  y_min = y_min - 0.05 * y_scale;
  y_scale = y_max - y_min;

  if ( x_scale < y_scale )

    delta = round ( ( x_ps_max - x_ps_min ) ...
      * ( y_scale - x_scale ) / ( 2.0 * y_scale ) );

    x_ps_max = x_ps_max - delta;
    x_ps_min = x_ps_min + delta;

    x_ps_max_clip = x_ps_max_clip - delta;
    x_ps_min_clip = x_ps_min_clip + delta;

    x_scale = y_scale;

  elseif ( y_scale < x_scale )

    delta = round ( ( y_ps_max - y_ps_min ) ...
      * ( x_scale - y_scale ) / ( 2.0 * x_scale ) );

    y_ps_max      = y_ps_max - delta;
    y_ps_min      = y_ps_min + delta;

    y_ps_max_clip = y_ps_max_clip - delta;
    y_ps_min_clip = y_ps_min_clip + delta;

    y_scale = x_scale;

  end
%
%  Plot the triangulation.
%
  file_unit = fopen ( file_name, 'wt' );

  if ( file_unit < 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'TRIANGULATION_ORDER3_PLOT - Fatal error!\n' );
    fprintf ( 1, '  Could not open the output file.\n' );
    error ( 'TRIANGULATION_ORDER3_PLOT - Fatal error!' );
  end

  fprintf ( file_unit, '%%!PS-Adobe-3.0 EPSF-3.0\n' );
  fprintf ( file_unit, '%%%%Creator: triangulation_order3_plot.m\n' );
  fprintf ( file_unit, '%%%%Title: %s\n', file_name );
  fprintf ( file_unit, '%%%%CreationDate: %s\n', date_time );
  fprintf ( file_unit, '%%%%Pages: 1\n' );
  fprintf ( file_unit, '%%%%BoundingBox:  %d  %d  %d  %d\n', ...
    x_ps_min, y_ps_min, x_ps_max, y_ps_max );
  fprintf ( file_unit, '%%%%Document-Fonts: Times-Roman\n' );
  fprintf ( file_unit, '%%%%LanguageLevel: 1\n' );
  fprintf ( file_unit, '%%%%EndComments\n' );
  fprintf ( file_unit, '%%%%BeginProlog\n' );
  fprintf ( file_unit, '/inch {72 mul} def\n' );
  fprintf ( file_unit, '%%%%EndProlog\n' );
  fprintf ( file_unit, '%%%%Page: 1 1\n' );
  fprintf ( file_unit, 'save\n' );
  fprintf ( file_unit, '%\n' );
  fprintf ( file_unit, '%  Increase line width from default 0.\n' );
  fprintf ( file_unit, '%\n' );
  fprintf ( file_unit, '2 setlinewidth\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Set the RGB color to very light gray.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '0.900  0.900  0.900 setrgbcolor\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Draw a gray border around the page.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, 'newpath\n' );
  fprintf ( file_unit, '  %d  %d  moveto\n', x_ps_min, y_ps_min );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max, y_ps_min );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max, y_ps_max );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min, y_ps_max );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min, y_ps_min );
  fprintf ( file_unit, 'stroke\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Set the RGB color to black.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '0.000  0.000  0.000 setrgbcolor\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Set the font and its size.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '/Times-Roman findfont\n' );
  fprintf ( file_unit, '0.50 inch scalefont\n' );
  fprintf ( file_unit, 'setfont\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Print a title.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%210  702  moveto\n' );
  fprintf ( file_unit, '%%(Triangulation)  show\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Define a clipping polygon.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, 'newpath\n' );
  fprintf ( file_unit, '  %d  %d  moveto\n', x_ps_min_clip, y_ps_min_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max_clip, y_ps_min_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max_clip, y_ps_max_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min_clip, y_ps_max_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min_clip, y_ps_min_clip );
  fprintf ( file_unit, 'clip newpath\n' );
%
%  Draw the nodes.
%
  if ( node_num <= 200 )
    circle_size = 5;
  elseif ( node_num <= 500 )
    circle_size = 4;
  elseif ( node_num <= 1000 )
    circle_size = 3;
  elseif ( node_num <= 5000 )
    circle_size = 2;
  else
    circle_size = 1;
  end

  if ( 1 <= node_show )

    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Draw filled dots at the nodes.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to blue.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.000  0.150  0.750 setrgbcolor\n' );
    fprintf ( file_unit, '%%\n' );

    for node = 1 : node_num

      x_ps = floor ( ...
        ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
        + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
        / ( x_max                   - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - node_xy(2,node)         ) * y_ps_min   ...
        + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
        / ( y_max                   - y_min ) );

      fprintf ( file_unit, ...
        '  newpath  %d  %d  %d 0 360 arc closepath fill\n', ...
        x_ps, y_ps, circle_size );

    end

  end
%
%  Label the nodes.
%
  if ( 2 <= node_show )
      
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Label the nodes.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to darker blue.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.000  0.250  0.850 setrgbcolor\n' );
    fprintf ( file_unit, '/Times-Roman findfont\n' );
    fprintf ( file_unit, '0.20 inch scalefont\n' );
    fprintf ( file_unit, 'setfont\n' );
    fprintf ( file_unit, '%%\n' );

    for node = 1 : node_num

      x_ps = floor ( ...
        ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
        + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
        / ( x_max                   - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - node_xy(2,node)         ) * y_ps_min   ...
        + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
        / ( y_max                   - y_min ) );

      fprintf ( file_unit, '  %d  %d  moveto (%d) show\n', ...
        x_ps, y_ps+5, node );

    end

  end
%
%  Draw the triangles.
%
  if ( 1 <= triangle_show )

    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to red.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.900  0.200  0.100 setrgbcolor\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Draw the triangles.\n' );
    fprintf ( file_unit, '%%\n' );

    for triangle = 1 : triangle_num

      fprintf ( file_unit, 'newpath\n' );

      for i = 1 : 4

        e = i;
        if ( e == 4 )
          e = 1;
        end

        node = triangle_node(e,triangle);

        x_ps = floor ( ...
          ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
          + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
          / ( x_max                   - x_min ) );

        y_ps = floor ( ...
          ( ( y_max - node_xy(2,node)         ) * y_ps_min ...
          + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
          / ( y_max                   - y_min ) );

        if ( i == 1 )
          fprintf ( file_unit, '  %d  %d  moveto\n', x_ps, y_ps );
        else
          fprintf ( file_unit, '  %d  %d  lineto\n', x_ps, y_ps );
        end

      end

      fprintf ( file_unit, 'stroke\n' );

    end

  end
%
%  Label the triangles.
%
  if ( 2 <= triangle_show )
      
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Label the triangles.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to darker red.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.950  0.250  0.150 setrgbcolor\n' );
    fprintf ( file_unit, '/Times-Roman findfont\n' );
    fprintf ( file_unit, '0.20 inch scalefont\n' );
    fprintf ( file_unit, 'setfont\n' );
    fprintf ( file_unit, '%%\n' );

    for triangle = 1 : triangle_num

      ave_x = 0.0;
      ave_y = 0.0;

      for i = 1 : 3
          
        node = triangle_node(i,triangle);
        ave_x = ave_x + node_xy(1,node);
        ave_y = ave_y + node_xy(2,node);
      end
      
      ave_x = ave_x / 3.0;
      ave_y = ave_y / 3.0;

      x_ps = floor ( ...
        ( ( x_max - ave_x         ) * x_ps_min ...
        + (         ave_x - x_min ) * x_ps_max ) ...
        / ( x_max         - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - ave_y         ) * y_ps_min ...
        + (         ave_y - y_min ) * y_ps_max ) ...
        / ( y_max         - y_min ) );

      fprintf ( file_unit, '  %d  %d  moveto (%d) show\n', ...
        x_ps, y_ps, triangle );

    end
  end

  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, 'restore  showpage\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  End of page.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%%%Trailer\n' );
  fprintf ( file_unit, '%%%%EOF\n' );

  fclose ( file_unit );

  return
end
function triangulation_order4_plot ( file_name, node_num, node_xy, ...
  triangle_num, triangle_node, node_show, triangle_show )

%*****************************************************************************80
%
%% TRIANGULATION_ORDER4_PLOT plots a 4-node triangulation of a pointset.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    08 June 2009
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, string FILE_NAME, the name of the output file.
%
%    Input, integer NODE_NUM, the number of points.
%
%    Input, real NODE_XY(2,NODE_NUM), the nodes.
%
%    Input, integer TRIANGLE_NUM, the number of triangles.
%
%    Input, integer TRIANGLE_NODE(4,TRIANGLE_NUM), lists, for each triangle,
%    the indices of the points that form the vertices of the triangle.
%
%    Input, logical NODE_SHOW:
%    0, do not show the nodes.
%    1, show the nodes.
%    2, show the nodes, and label them.
%
%    Input, logical TRIANGLE_SHOW, 
%    0, do not show the triangles.
%    1, show the triangles.
%    2, show the triangles, and label them.
%
  x_ps_max = 576;
  x_ps_max_clip = 594;
  x_ps_min = 36;
  x_ps_min_clip = 18;
  y_ps_max = 666;
  y_ps_max_clip = 684;
  y_ps_min = 126;
  y_ps_min_clip = 108;

  date_time = timestring ( );
%
%  We need to do some figuring here, so that we can determine
%  the range of the data, and hence the height and width
%  of the piece of paper.
%
  x_max = max ( node_xy(1,1:node_num) );
  x_min = min ( node_xy(1,1:node_num) );
  x_scale = x_max - x_min;
  
  x_max = x_max + 0.05 * x_scale;
  x_min = x_min - 0.05 * x_scale;
  x_scale = x_max - x_min;

  y_max = max ( node_xy(2,1:node_num) );
  y_min = min ( node_xy(2,1:node_num) );
  y_scale = y_max - y_min;

  y_max = y_max + 0.05 * y_scale;
  y_min = y_min - 0.05 * y_scale;
  y_scale = y_max - y_min;

  if ( x_scale < y_scale )

    delta = round ( ( x_ps_max - x_ps_min ) ...
      * ( y_scale - x_scale ) / ( 2.0 * y_scale ) );

    x_ps_max = x_ps_max - delta;
    x_ps_min = x_ps_min + delta;

    x_ps_max_clip = x_ps_max_clip - delta;
    x_ps_min_clip = x_ps_min_clip + delta;

    x_scale = y_scale;

  elseif ( y_scale < x_scale )

    delta = round ( ( y_ps_max - y_ps_min ) ...
      * ( x_scale - y_scale ) / ( 2.0 * x_scale ) );

    y_ps_max      = y_ps_max - delta;
    y_ps_min      = y_ps_min + delta;

    y_ps_max_clip = y_ps_max_clip - delta;
    y_ps_min_clip = y_ps_min_clip + delta;

    y_scale = x_scale;

  end
%
%  Plot the triangulation.
%
  file_unit = fopen ( file_name, 'wt' );

  if ( file_unit < 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'TRIANGULATION_ORDER4_PLOT - Fatal error!\n' );
    fprintf ( 1, '  Could not open the output file.\n' );
    error ( 'TRIANGULATION_ORDER4_PLOT - Fatal error!' );
  end

  fprintf ( file_unit, '%%!PS-Adobe-3.0 EPSF-3.0\n' );
  fprintf ( file_unit, '%%%%Creator: triangulation_order4_plot.m\n' );
  fprintf ( file_unit, '%%%%Title: %s\n', file_name );
  fprintf ( file_unit, '%%%%CreationDate: %s\n', date_time );
  fprintf ( file_unit, '%%%%Pages: 1\n' );
  fprintf ( file_unit, '%%%%BoundingBox:  %d  %d  %d  %d\n', ...
    x_ps_min, y_ps_min, x_ps_max, y_ps_max );
  fprintf ( file_unit, '%%%%Document-Fonts: Times-Roman\n' );
  fprintf ( file_unit, '%%%%LanguageLevel: 1\n' );
  fprintf ( file_unit, '%%%%EndComments\n' );
  fprintf ( file_unit, '%%%%BeginProlog\n' );
  fprintf ( file_unit, '/inch {72 mul} def\n' );
  fprintf ( file_unit, '%%%%EndProlog\n' );
  fprintf ( file_unit, '%%%%Page: 1 1\n' );
  fprintf ( file_unit, 'save\n' );
  fprintf ( file_unit, '%\n' );
  fprintf ( file_unit, '%  Increase line width from default 0.\n' );
  fprintf ( file_unit, '%\n' );
  fprintf ( file_unit, '2 setlinewidth\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Set the RGB color to very light gray.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '0.900  0.900  0.900 setrgbcolor\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Draw a gray border around the page.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, 'newpath\n' );
  fprintf ( file_unit, '  %d  %d  moveto\n', x_ps_min, y_ps_min );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max, y_ps_min );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max, y_ps_max );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min, y_ps_max );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min, y_ps_min );
  fprintf ( file_unit, 'stroke\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Set the RGB color to black.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '0.000  0.000  0.000 setrgbcolor\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Set the font and its size.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '/Times-Roman findfont\n' );
  fprintf ( file_unit, '0.50 inch scalefont\n' );
  fprintf ( file_unit, 'setfont\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Print a title.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%210  702  moveto\n' );
  fprintf ( file_unit, '%%(Triangulation)  show\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Define a clipping polygon.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, 'newpath\n' );
  fprintf ( file_unit, '  %d  %d  moveto\n', x_ps_min_clip, y_ps_min_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max_clip, y_ps_min_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max_clip, y_ps_max_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min_clip, y_ps_max_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min_clip, y_ps_min_clip );
  fprintf ( file_unit, 'clip newpath\n' );
%
%  Draw the nodes.
%
  if ( node_num <= 200 )
    circle_size = 5;
  elseif ( node_num <= 500 )
    circle_size = 4;
  elseif ( node_num <= 1000 )
    circle_size = 3;
  elseif ( node_num <= 5000 )
    circle_size = 2;
  else
    circle_size = 1;
  end

  if ( 1 <= node_show )

    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Draw filled dots at the nodes.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to blue.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.000  0.150  0.750 setrgbcolor\n' );
    fprintf ( file_unit, '%%\n' );

    for node = 1 : node_num

      x_ps = floor ( ...
        ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
        + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
        / ( x_max                   - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - node_xy(2,node)         ) * y_ps_min   ...
        + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
        / ( y_max                   - y_min ) );

      fprintf ( file_unit, ...
        '  newpath  %d  %d  %d 0 360 arc closepath fill\n', ...
        x_ps, y_ps, circle_size );

    end

  end
%
%  Label the nodes.
%
  if ( 2 <= node_show )
      
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Label the nodes.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to darker blue.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.000  0.250  0.850 setrgbcolor\n' );
    fprintf ( file_unit, '/Times-Roman findfont\n' );
    fprintf ( file_unit, '0.20 inch scalefont\n' );
    fprintf ( file_unit, 'setfont\n' );
    fprintf ( file_unit, '%%\n' );

    for node = 1 : node_num

      x_ps = floor ( ...
        ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
        + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
        / ( x_max                   - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - node_xy(2,node)         ) * y_ps_min   ...
        + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
        / ( y_max                   - y_min ) );

      fprintf ( file_unit, '  %d  %d  moveto (%d) show\n', ...
        x_ps, y_ps+5, node );

    end

  end
%
%  Draw the triangles.
%
  if ( 1 <= triangle_show )

    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to red.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.900  0.200  0.100 setrgbcolor\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Draw the triangles.\n' );
    fprintf ( file_unit, '%%\n' );

    for triangle = 1 : triangle_num

      fprintf ( file_unit, 'newpath\n' );

      for i = 1 : 4

        e = i;
        if ( e == 4 )
          e = 1;
        end

        node = triangle_node(e,triangle);

        x_ps = floor ( ...
          ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
          + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
          / ( x_max                   - x_min ) );

        y_ps = floor ( ...
          ( ( y_max - node_xy(2,node)         ) * y_ps_min ...
          + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
          / ( y_max                   - y_min ) );

        if ( i == 1 )
          fprintf ( file_unit, '  %d  %d  moveto\n', x_ps, y_ps );
        else
          fprintf ( file_unit, '  %d  %d  lineto\n', x_ps, y_ps );
        end

      end

      fprintf ( file_unit, 'stroke\n' );

    end

  end
%
%  Label the triangles.
%
  if ( 2 <= triangle_show )
      
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Label the triangles.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to darker red.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.950  0.250  0.150 setrgbcolor\n' );
    fprintf ( file_unit, '/Times-Roman findfont\n' );
    fprintf ( file_unit, '0.20 inch scalefont\n' );
    fprintf ( file_unit, 'setfont\n' );
    fprintf ( file_unit, '%%\n' );

    for triangle = 1 : triangle_num

      ave_x = 0.0;
      ave_y = 0.0;

      for i = 1 : 3
          
        node = triangle_node(i,triangle);
        ave_x = ave_x + node_xy(1,node);
        ave_y = ave_y + node_xy(2,node);
      end
      
      ave_x = ave_x / 3.0;
      ave_y = ave_y / 3.0;

      x_ps = floor ( ...
        ( ( x_max - ave_x         ) * x_ps_min ...
        + (         ave_x - x_min ) * x_ps_max ) ...
        / ( x_max         - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - ave_y         ) * y_ps_min ...
        + (         ave_y - y_min ) * y_ps_max ) ...
        / ( y_max         - y_min ) );

      fprintf ( file_unit, '  %d  %d  moveto (%d) show\n', ...
        x_ps, y_ps, triangle );

    end
  end

  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, 'restore  showpage\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  End of page.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%%%Trailer\n' );
  fprintf ( file_unit, '%%%%EOF\n' );

  fclose ( file_unit );

  return
end
function triangulation_order6_plot ( file_name, node_num, node_xy, ...
  triangle_num, triangle_node, node_show, triangle_show )

%*****************************************************************************80
%
%% TRIANGULATION_ORDER6_PLOT plots a 6-node triangulation of a pointset.
%
%  Discussion:
%
%    The triangulation is most usually a Delaunay triangulation,
%    but this is not necessary.
%
%    In a six node triangulation, it is assumed that nodes 1, 2, and 3
%    are the vertices of the triangles, and that nodes 4, 5, and 6
%    lie between 1 and 2, 2 and 3, and 3 and 1 respectively.
%
%    This routine has been specialized to deal correctly ONLY with
%    a mesh of 6 node elements, with the property that starting
%    from local node 1 and traversing the edges of the element will
%    result in encountering local nodes 1, 4, 2, 5, 3, 6 in that order.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    08 June 2009
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, character FILE_NAME(*), the name of the output file.
%
%    Input, integer NODE_NUM, the number of points.
%
%    Input, real NODE_XY(2,NODE_NUM), the nodes.
%
%    Input, integer TRIANGLE_NUM, the number of triangles.
%
%    Input, integer TRIANGLE_NODE(6,TRIANGLE_NUM), lists, for each triangle,
%    the indices of the points that form the vertices and midsides 
%    of the triangle.
%
%    Input, logical NODE_SHOW:
%    0, do not show the nodes.
%    1, show the nodes.
%    2, show the nodes, and label them.
%
%    Input, logical TRIANGLE_SHOW, 
%    0, do not show the triangles.
%    1, show the triangles.
%    2, show the triangles, and label them.
%
  order = [ 1, 4, 2, 5, 3, 6 ];
  x_ps_max = 576;
  x_ps_max_clip = 594;
  x_ps_min = 36;
  x_ps_min_clip = 18;
  y_ps_max = 666;
  y_ps_max_clip = 684;
  y_ps_min = 126;
  y_ps_min_clip = 108;

  date_time = timestring ( );
%
%  We need to do some figuring here, so that we can determine
%  the range of the data, and hence the height and width
%  of the piece of paper.
%
  x_max = max ( node_xy(1,1:node_num) );
  x_min = min ( node_xy(1,1:node_num) );
  x_scale = x_max - x_min;
  
  x_max = x_max + 0.05 * x_scale;
  x_min = x_min - 0.05 * x_scale;
  x_scale = x_max - x_min;

  y_max = max ( node_xy(2,1:node_num) );
  y_min = min ( node_xy(2,1:node_num) );
  y_scale = y_max - y_min;

  y_max = y_max + 0.05 * y_scale;
  y_min = y_min - 0.05 * y_scale;
  y_scale = y_max - y_min;

  if ( x_scale < y_scale )

    delta = round ( ( x_ps_max - x_ps_min ) ...
      * ( y_scale - x_scale ) / ( 2.0 * y_scale ) );

    x_ps_max = x_ps_max - delta;
    x_ps_min = x_ps_min + delta;

    x_ps_max_clip = x_ps_max_clip - delta;
    x_ps_min_clip = x_ps_min_clip + delta;

    x_scale = y_scale;

  elseif ( y_scale < x_scale )

    delta = round ( ( y_ps_max - y_ps_min ) ...
      * ( x_scale - y_scale ) / ( 2.0 * x_scale ) );

    y_ps_max      = y_ps_max - delta;
    y_ps_min      = y_ps_min + delta;

    y_ps_max_clip = y_ps_max_clip - delta;
    y_ps_min_clip = y_ps_min_clip + delta;

    y_scale = x_scale;

  end
%
%  Plot the triangulation.
%
  file_unit = fopen ( file_name, 'wt' );

  if ( file_unit < 0 )
    fprintf ( 1, '\n' );
    fprintf ( 1, 'TRIANGULATION_ORDER6_PLOT - Fatal error!\n' );
    fprintf ( 1, '  Could not open the output file.\n' );
    error ( 'TRIANGULATION_ORDER6_PLOT - Fatal error!' );
  end

  fprintf ( file_unit, '%%!PS-Adobe-3.0 EPSF-3.0\n' );
  fprintf ( file_unit, '%%%%Creator: triangulation_order6_plot.m\n' );
  fprintf ( file_unit, '%%%%Title: %s\n', file_name );
  fprintf ( file_unit, '%%%%CreationDate: %s\n', date_time );
  fprintf ( file_unit, '%%%%Pages: 1\n' );
  fprintf ( file_unit, '%%%%BoundingBox:  %d  %d  %d  %d\n', ...
    x_ps_min, y_ps_min, x_ps_max, y_ps_max );
  fprintf ( file_unit, '%%%%Document-Fonts: Times-Roman\n' );
  fprintf ( file_unit, '%%%%LanguageLevel: 1\n' );
  fprintf ( file_unit, '%%%%EndComments\n' );
  fprintf ( file_unit, '%%%%BeginProlog\n' );
  fprintf ( file_unit, '/inch {72 mul} def\n' );
  fprintf ( file_unit, '%%%%EndProlog\n' );
  fprintf ( file_unit, '%%%%Page: 1 1\n' );
  fprintf ( file_unit, 'save\n' );
  fprintf ( file_unit, '%\n' );
  fprintf ( file_unit, '%  Increase line width from default 0.\n' );
  fprintf ( file_unit, '%\n' );
  fprintf ( file_unit, '2 setlinewidth\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Set the RGB color to very light gray.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '0.900  0.900  0.900 setrgbcolor\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Draw a gray border around the page.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, 'newpath\n' );
  fprintf ( file_unit, '  %d  %d  moveto\n', x_ps_min, y_ps_min );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max, y_ps_min );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max, y_ps_max );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min, y_ps_max );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min, y_ps_min );
  fprintf ( file_unit, 'stroke\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Set the RGB color to black.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '0.000  0.000  0.000 setrgbcolor\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Set the font and its size.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '/Times-Roman findfont\n' );
  fprintf ( file_unit, '0.50 inch scalefont\n' );
  fprintf ( file_unit, 'setfont\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Print a title.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%210  702  moveto\n' );
  fprintf ( file_unit, '%%(Triangulation)  show\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%  Define a clipping polygon.\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, 'newpath\n' );
  fprintf ( file_unit, '  %d  %d  moveto\n', x_ps_min_clip, y_ps_min_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max_clip, y_ps_min_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_max_clip, y_ps_max_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min_clip, y_ps_max_clip );
  fprintf ( file_unit, '  %d  %d  lineto\n', x_ps_min_clip, y_ps_min_clip );
  fprintf ( file_unit, 'clip newpath\n' );
%
%  Draw the nodes.
%
  if ( node_num <= 200 )
    circle_size = 5;
  elseif ( node_num <= 500 )
    circle_size = 4;
  elseif ( node_num <= 1000 )
    circle_size = 3;
  elseif ( node_num <= 5000 )
    circle_size = 2;
  else
    circle_size = 1;
  end

  if ( 1 <= node_show )

    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Draw filled dots at the nodes.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to blue.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.000  0.150  0.750 setrgbcolor\n' );
    fprintf ( file_unit, '%%\n' );

    for node = 1 : node_num

      x_ps = floor ( ...
        ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
        + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
        / ( x_max                   - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - node_xy(2,node)         ) * y_ps_min   ...
        + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
        / ( y_max                   - y_min ) );

      fprintf ( file_unit, ...
        '  newpath  %d  %d  %d 0 360 arc closepath fill\n', ...
        x_ps, y_ps, circle_size );

    end

  end 
%
%  Label the nodes.
%
  if ( 2 <= node_show )
      
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Label the nodes.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to darker blue.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.000  0.250  0.850 setrgbcolor\n' );
    fprintf ( file_unit, '/Times-Roman findfont\n' );
    fprintf ( file_unit, '0.20 inch scalefont\n' );
    fprintf ( file_unit, 'setfont\n' );
    fprintf ( file_unit, '%%\n' );

    for node = 1 : node_num

      x_ps = floor ( ...
        ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
        + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
        / ( x_max                   - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - node_xy(2,node)         ) * y_ps_min   ...
        + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
        / ( y_max                   - y_min ) );

      fprintf ( file_unit, '  %d  %d  moveto (%d) show\n', ...
        x_ps, y_ps+5, node );

    end

  end
%
%  Draw the triangles.
%
  if ( 1 <= triangle_show )

    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to red.\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '0.900  0.200  0.100 setrgbcolor\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%  Draw the triangles.\n' );
    fprintf ( file_unit, '%%\n' );

    for  triangle = 1 : triangle_num

      fprintf ( file_unit, 'newpath\n' );

      node = triangle_node(order(1),triangle);

      x_ps = floor ( ...
        ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
        + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
        / ( x_max                   - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - node_xy(2,node)         ) * y_ps_min ...
        + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
        / ( y_max                   - y_min ) );

      fprintf ( file_unit, '%d  %d  moveto\n', x_ps, y_ps );
  
      for i = 1 : 6

        ip1 = mod ( i, 6 ) + 1;
        node = triangle_node(order(ip1),triangle);

        x_ps = floor ( ...
          ( ( x_max - node_xy(1,node)         ) * x_ps_min ...
          + (         node_xy(1,node) - x_min ) * x_ps_max ) ...
          / ( x_max                   - x_min ) );

        y_ps = floor ( ...
          ( ( y_max - node_xy(2,node)         ) * y_ps_min ...
          + (         node_xy(2,node) - y_min ) * y_ps_max ) ...
          / ( y_max                   - y_min ) );

        fprintf ( file_unit, '%d  %d  lineto\n', x_ps, y_ps );

      end

      fprintf ( file_unit, 'stroke\n' );

    end

  end
%
%  Label the triangles.
%
  if ( 2 <= triangle_show )

    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Label the triangles:\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, '%%  Set the RGB color to darker red:\n' );
    fprintf ( file_unit, '%%\n' );
    fprintf ( file_unit, ' 0.950  0.250  0.150  setrgbcolor\n' );
    fprintf ( file_unit, '/Times-Roman findfont\n' );
    fprintf ( file_unit, '0.30 inch scalefont\n' );
    fprintf ( file_unit, 'setfont\n' );

    for triangle = 1 : triangle_num

      ave_x = 0.0;
      ave_y = 0.0;

      for i = 1 : 6
        node = triangle_node(i,triangle);
        ave_x = ave_x + node_xy(1,node);
        ave_y = ave_y + node_xy(2,node);
      end

      ave_x = ave_x / 6.0;
      ave_y = ave_y / 6.0;

      x_ps = floor ( ...
        ( ( x_max - ave_x         ) * x_ps_min ...
        + (         ave_x - x_min ) * x_ps_max ) ...
        / ( x_max         - x_min ) );

      y_ps = floor ( ...
        ( ( y_max - ave_y         ) * y_ps_min ...
        + (         ave_y - y_min ) * y_ps_max ) ...
        / ( y_max         - y_min ) );

      fprintf ( file_unit, '%d  %d  moveto\n', x_ps, y_ps );
      fprintf ( file_unit, '(%d) show\n', triangle );

    end

  end

  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, 'restore showpage\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%% End of page\n' );
  fprintf ( file_unit, '%%\n' );
  fprintf ( file_unit, '%%%%Trailer\n' );
  fprintf ( file_unit, '%%%%EOF\n' );

  fclose ( file_unit );

  return
end