function  bc_flags_plot ()
% Copyright 2000, J.E. Akin.  All rights reserved.
% function  bc_flags_plot (inc_e, inc_p)
%  ------------------------------------------------------
%  Matlab program to calculate & plot 2-D FE mesh BC flags
%  (needs fix to include leading zeros)
%  ------------------------------------------------------

% c_x    = x coordinates of nod_per_el line polygon
% c_y    = y coordinates of nod_per_el line polygon
% inc_e  = increment in element numbers on plot, if > 0
% inc_p  = increment in node numbers on plot, if > 0
% msh_typ_nodes   = connectivity list for elements, nt x nod_per_el
% loop   = corners for nod_per_el line polygon
% lab_p  = 1, if node points are circled
  lab_p  = 0;
% nod_per_el = Nodes per element
% np     = Number of Points
% nt     = Number of elements
% pre_e  = Element items before connectivity list
  pre_e  = 0 ;
% pre_p  = Nodal items before coordinates
  pre_p = 1;
% msh_bc_xyz = Nodal coordinates (with preceeding data)
% t_x    = x coordinates of nod_per_el corners
% t_y    = y coordinates of nod_per_el corners
% x_bar  = x-centroid of each element
% xy     = Coordinates of points, np x 2
% y_bar  = y-centroid of each element

%    Read coordinate file and connectivity file
%    integer bc code, real xy pairs for np points (pre_p = 1)

%    Set control data: number of points
  load msh_bc_xyz.tmp ;  
  np = size (msh_bc_xyz,1) ;   % number of nodal points  
  ns = size (msh_bc_xyz,2) - pre_p ;   % dimension of space
  if ( np == 0 )
    error ('Error missing file msh_bc_xyz.tmp')
  end % if error
  fprintf ('Read %g mesh coordinate pairs \n', np)
  % fprintf ('       x        y \n')

  x (np)      = 0.       ;       % pre-allocate array x
  y (np)      = 0.       ;       % pre-allocate array y

  % msh_bc_xyz has: pre_p items then: x, y
  bc = msh_bc_xyz (1:np, pre_p) ; % extract bc flags
  x  = msh_bc_xyz (1:np, (pre_p+1)) ; % extract x column of xy
  if ( ns >= 2)
    y = msh_bc_xyz (1:np, (pre_p+2)) ; % extract y column of xy
  else
    y (1:np) = 0. ;
  end % if 1D
  
%    Set control data: number elements & nodes_per_element
  load  msh_typ_nodes.tmp ; % nod_per_el nodes per element
  nt         = size (msh_typ_nodes,1);           % number of elements 
  if ( nt == 0 )
    error ('Error missing file msh_typ_nodes.tmp')
  end % if error
  nod_per_el = size (msh_typ_nodes,2) - pre_e -1 ; % nodes per element
  fprintf ('Read %g elements with %g nodes each \n', nt,nod_per_el)

%  x_bar (nt)  = 0.       ;       % pre-allocate array x_bar
%  y_bar (nt)  = 0.       ;       % pre-allocate array y_bar
  t_nodes (nod_per_el) = 0 ;    % Optional pre-allocation
  t_x (nod_per_el) = 0 ;        % Optional pre-allocation
  t_y (nod_per_el) = 0 ;        % Optional pre-allocation
  c_x (nod_per_el + 1) = 0 ;    % Optional pre-allocation
  c_y (nod_per_el + 1) = 0 ;    % Optional pre-allocation
  loop (nod_per_el + 1) = 0 ;   % Optional pre-allocation
 
%                set constants
  [loop] = get_El_Loop (nod_per_el) ;
  %b fprintf ('Begin element plots:')

%    Initialize plots
  xmax = max (x)      ; xmin = min (x) ;
  ymax = max (y)      ; ymin = min (y) ;
  xdiff = xmax - xmin ; ydiff = ymax - ymin ;
  if ( ydiff == 0.0 )
    ydiff = 0.5 ; % allow for 1-D mesh (with y == 0)
  end % if no y coordinates
  xmax = xmax + xdiff/10; ymax = ymax + ydiff/10;
  xmin = xmin - xdiff/10; ymin = ymin - ydiff/10;
  clf                               % clear graphics
  axis ([xmin, xmax, ymin, ymax])   % set axes
  axis ('equal')                    % true shape style
  hold on                           % hold image for plots
  grid                              % add grid dots
% xlabel ('X')                      % add label
xlabel (['X for ', int2str(nt),' Elements with ', ...
        int2str(nod_per_el), ' nodes'])
  ylabel ('Y')                      % add label
 
%      Plot input mesh points & label them
  if (lab_p == 1)                   % plot all points
    plot (x, y, 'b.')               % mark each node
  end % if show labels

%%    Show 20 nodes and 10 elements, or all for small mesh
%  inc_p = floor(np/20) ; inc_e = floor(nt/10) ;
%  if (inc_p == 0 ) 
%    inc_p = np - 1 ;
%  end % if inc_p
%  if (inc_e == 0 ) 
%    inc_e = nt - 1 ;
%  end % if inc_e
%%    Show all if a small mesh
%  if ( np <= 20 )
%    inc_p = 1 ;
%  end % if np
%  if ( nt <= 10 )
%    inc_e = 1 ;
%  end % if nt

%  if (inc_p > 0)      % plot node numbers, if node in mesh
%   in_mesh (1:np) = 0 ;               % default to missing
%   for i = 1:nt                       % loop all elements
%     for j = 1:nod_per_el             % loop its nodes
%       in_mesh (msh_typ_nodes(i, j+1)) = 1; % flag as present
%     end % for its nodes
%   end % for all elements
%   % disp (in_mesh)
%  end % if show labels
%  disp (' ')

%    Loop over all elements
  for it = 1:nt  ;

%      Extract corner connectivity 
    t_nodes = msh_typ_nodes (it, (pre_e+2):(nod_per_el+pre_e + 1)); 

%      Extract corner coordinates
    t_x  = x (t_nodes) ;         % x at those nodes, only
    t_y  = y (t_nodes) ;         % y at those nodes, only

%%      Get the centroid
%    x_bar (it) = sum (t_x' )/nod_per_el ;
%    y_bar (it) = sum (t_y' )/nod_per_el ;

%      Plot this polygon
    c_x  = t_x (loop) ;       % x for nod_per_el line polygon
    c_y  = t_y (loop) ;       % y for nod_per_el line polygon
    plot (c_x, c_y)           % plot nod_per_el lines
  end % for over all elements
 
%%    Finish the plots with polygon numbers
%  if (inc_e > 0)                     % plot elem number, inclined
%    plot (x_bar, y_bar, 'g.')        % centroid of each element
%    for i = 1:inc_e:nt               % convert to string
%      t_text = sprintf ('  %g', i);  % offset # from pt
%      text (x_bar(i), y_bar(i), t_text, 'Rotation', 45) % incline
%    end % for all polygons
%  end % if show labels

%     Finish with BC & MPC flags
   given = 0 ;
   ng = max (bc)
   if ( ng >= 100000 )
     ng = 6
   elseif ( ng >= 10000 )
     ng = 5
   elseif ( ng >= 1000 )
     ng = 4
   elseif ( ng >= 100 )
     ng = 3
   elseif ( ng >= 10 )
     ng = 2
   else 
     ng = 1
   end %if number of digits to show
   for i = 1:np                 % loop over all nodes
     if ( bc (i) > 0 )           % it has BC or MPC
       if ( ng == 6 )
         p_text = sprintf ('-- %i (%6.6i)', i, bc(i));   % offset
       elseif ( ng == 5 )
         p_text = sprintf ('-- %i (%5.5i)', i, bc(i));   % offset
       elseif ( ng == 4 )
         p_text = sprintf ('-- %i (%4.4i)', i, bc(i));   % offset
       elseif ( ng == 3 )
         p_text = sprintf ('-- %i (%3.3i)', i, bc(i));   % offset
       elseif ( ng == 2 )
         p_text = sprintf ('-- %i (%2.2i)', i, bc(i));   % offset
       else
         p_text = sprintf ('-- %i (%i)', i, bc(i));   % offset
       end % if number of required digits
       %b p_text = sprintf ('-- %g (%i)', i, bc(i));   % offset # from pt
       text (x(i), y(i), p_text, 'Rotation', 30) % incline flags
       given = given + 1 ;
     end % if present
   end % for all points

  title  (['FE Mesh; ', int2str(np), ...
          ' Nodes, ', int2str(given), ' with BC or MPC Noted'])

%       -depsc -tiff            % for an eps version
  %bprint -dpsc bc_flags_plot
  hold off
  %bfprintf ('Created file bc_flags_plot.ps \n')
% end of bc_flags_plot