function  color_el_at_a_node (L_1)
% Copyright 2000, J.E. Akin.  All rights reserved.
%  ------------------------------------------------------
%  Matlab plot 2-D FE element L_1
%  and include full mesh if mesh=1
%  ------------------------------------------------------

% 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 %-error on plot, if > 0
  inc_e  = 1 ;
% 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
% 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  
  fprintf ('Read %g mesh coordinate pairs \n', np)
  % fprintf ('       x        y \n')
  
%    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 in mesh 
  nod_per_el = size (msh_typ_nodes,2) - pre_e -1 ; % nodes per element
  fprintf ('Read %g elements connections \n', nt)
  
  x (np)      = 0.       ;       % pre-allocate array x
  y (np)      = 0.       ;       % pre-allocate array y
  % 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) ;

  % msh_bc_xyz has: pre_p items then: x, y
  x = msh_bc_xyz (1:np, (pre_p+1)) ; % extract x column of xy
  y = msh_bc_xyz (1:np, (pre_p+2)) ; % extract y column of xy
 
%    Initialize plots
  xmax = max (x)      ; xmin = min (x) ;
  ymax = max (y)      ; ymin = min (y) ;
  %b xdiff = xmax - xmin ; ydiff = ymax - ymin ;
  %b if ( ydiff == 0.0 )
    %b ydiff = 0.5 ; % allow for 1-D mesh (with y == 0)
  %b end % if no y coordinates
  %b xmax = xmax + xdiff/10; ymax = ymax + ydiff/10;
  %b 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: ', int2str(nt),' Elements (with ', ...
          int2str(nod_per_el), ' nodes)'])
  ylabel (['Y: ', int2str(np),' Nodes'])
  format compact
  format short
 
%    Loop over all elements
  mesh = 1 ;
  lab_p = 1 
  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

%      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
    if ( mesh == 1 ) % add all element outlines
      plot (c_x, c_y)    % plot element color
    end % if mesh
    if ( it == L_1 ) % then node on element
% fill element color
      fill (c_x, c_y, 'g')    
      if ( lab_p == 1 )
% plot elem number, inclined
        t_text = sprintf ('%g', it);  % offset # from pt
        x_bar  = sum (t_x' )/nod_per_el ;
        y_bar  = sum (t_y' )/nod_per_el ;
        text (x_bar, y_bar, t_text) % incline
        %b text (x_bar, y_bar, t_text, 'Rotation', 45) % incline
% show node nunmbers
        for j = 1:nod_per_el
          node = t_nodes(j) ;
          if ( node > 0 ) % plot
            p_text = sprintf ('<-- %g', node);
            text (x(node), y(node), p_text)
          end % if
        end % for j
      end % if label nodes
    end % if any
  end % for full mesh

  title([' Element ', int2str(L_1)])

%       -depsc -tiff            % for an eps version
  %b print -dpsc color_el_at_a_node
  hold off
%b fprintf ('Created file color_el_at_a_node.ps \n')
% end of color_el_at_a_node