function  mode_2d_mesh_plot (mode, inc_m, inc_e, inc_p) 
% inc_m = 1, include original mesh, else omit
% inc_e  = increment in element numbers on plot, if > 0
% inc_p  = increment in node numbers on plot, if > 0
% Copyright 2008, J.E. Akin.  All rights reserved.
%  ------------------------------------------------------
%  Matlab program to plot 2-D deformed FE meshes
%  ------------------------------------------------------
% UNDER CONSTRUCTION
% d_scale = deflection multiplier (default 100)
% c_x    = x coordinates of nod_per_el line polygon
% c_y    = y coordinates of nod_per_el line polygon
% 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_p  = Nodal items before coordinates
% pre_r  = Nodal items before results %CL
% msh_bc_xyz = Nodal coordinates (with preceeding data)
% row    = row number where cord & connectivity start, 1 or 2 %CL
row = 1;
% sx, sy = scaled mesh positions = x + d_scale * x_def, etc
% 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

  pre_e  = 0 ; pre_p = 1; pre_r = 0 ; d_scale = 1.0 ; 
  format short g
  if ( nargin == 0 )
    mode = 1 ; inc_m = 1; inc_e = 0; inc_p = 0; 
  end % if no arguments
  if ( nargin == 1 )
    inc_m = 1; inc_e = 0; inc_p = 0; 
  end % if no arguments
  if ( nargin == 2 )
    inc_e = 0; inc_p = 0; 
  end % if no arguments
  if ( nargin == 3 )
    inc_p = 0; 
  end % if no arguments
  less = row - 1 ; %CL
  % fprintf ('Using scale %g, d_scale ')

%    Read coordinate file and connectivity file
%    integer bc code, real xy pairs for np points 

%    Set control data: number of points
  load msh_bc_xyz.tmp ;  
  np = size (msh_bc_xyz,1) ;   % number of nodal points  
  np = np - less ;   %CL
  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 ('and %g coordinate pairs \n', np)

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

  % msh_bc_xyz has: pre_p items then: x, y
  %b x = msh_bc_xyz (1:np, (pre_p+1)) ; % extract x column of xy
  x = msh_bc_xyz (row:(np+less), (pre_p+1)) ; % extract x  %CL
  if ( ns >= 2 )
    %b y = msh_bc_xyz (1:np, (pre_p+2)) ; % extract y column of xy
    y = msh_bc_xyz (row:(np+less), (pre_p+2)) ; % extract y %CL
  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 
  nt = nt - less ; %CL
  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)
  Col_1 = pre_e+2 ; %CL
  Col_2 = nod_per_el+pre_e+1 ; %CL

%    Get deflections
  load mode_value_vector.tmp % (np * n_modes) x 4
% mode numnber, value, components at all nodes
  nd = size (mode_value_vector, 1) ;
  if ( nd == 0 )
    error ('Error missing file mode_value_vector.tmp')
  end % if error
  n_modes = nd / np ; % number of modes provided
  Freq = mode_value_vector (mode*np, 2) ; % frequency

  %b [X_X, L_X] = max ( abs (mode_value_vector (:, pre_r+1)) ) ; %CL
  %b [Y_X, L_Y] = max ( abs (mode_value_vector (:, pre_r+2)) ); %CL
  %b Max_Disp = max (X_X, Y_X) ;
  maxx  = max (x)    ; minx = min (x) ;
  maxy  = max (y)    ; miny = min (y) ;
  Max_Len= max((maxx-minx),(maxy-miny)) ;
  %b Good_Scale=Max_Len/Max_Disp/20 ;
  Good_Scale=Max_Len/10 ;
  fprintf ('Suggested scale = %g \n', Good_Scale)
  maxx = maxx*1.1 ; minx = minx*1.1 ;
  maxy = maxy*1.1 ; miny = miny*1.1 ;

%  define mode "deformed" shape
  start = (mode - 1)*np ;
  sx = x + Good_Scale * mode_value_vector (start+1:start+np, 3) ;
  sy = y + Good_Scale * mode_value_vector (start+1:start+np, 4) ;

  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) ;

%    Initialize plots
  clf                               % clear graphics
  %b axis ([xmin, xmax, ymin, ymax])   % set axes
  axis ([minx, maxx, miny, maxy])   % set axes
  axis ('equal')                    % true shape style
  hold on                           % hold image for plots
  grid                              % add grid dots

xlabel (['X for ', int2str(nt),' Elements (with ', ...
        int2str(nod_per_el), ' nodes)'])
  ylabel (['Y for ', int2str(np), ' Nodes'])    
  title  (['Mode Shape ' int2str(mode), ', Freq = ', ...
          num2str(Freq), ' (solid): Scale = ', num2str(d_scale)])
 
%      Plot input mesh points & label them
  if (lab_p == 1)                   % plot all points
    plot (x, y, 'b.')               % mark each node
  end % if show labels

%  if ( nargin == 0 ) % select increments
%%    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
%  end % if no arguments

  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
       %b in_mesh (msh_typ_nodes(i, j)) = 1; % flag as present
       in_mesh (msh_typ_nodes(i+less, j+pre_e+1)) = 1; % present %CL
     end % for its nodes
   end % for all elements

   for i = 1:inc_p:np                 % convert to string
     %b if ( in_mesh (i) > 0 )           % it is present
      p_text = sprintf ('  %g', i);   % offset # from pt
      text (x(i), y(i), p_text)       % plot pt number
     %b end % if present
   end % for all points
  end % if show labels
  disp (' ')

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

%      Extract corner connectivity 
    %b t_nodes = msh_typ_nodes (it, (pre_e+2):(nod_per_el+pre_e+1)); 
    t_nodes = msh_typ_nodes ((it+less), Col_1:Col_2 ) ; %CL

%      Plot the original ploygon
    if ( inc_m == 1)
      t_x  = x (t_nodes) ;         % x original
      t_y  = y (t_nodes) ;         % y original
      c_x  = t_x (loop) ;
      c_y  = t_y (loop) ;
      plot (c_x, c_y, 'g--') 
    end % if original mesh

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

%      Plot this deformed 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
    for it = 1:inc_e:nt               % convert to string
 %      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 = sum (t_x' )/nod_per_el ;
      y_bar = sum (t_y' )/nod_per_el ;

      plot (x_bar, y_bar, 'g.')        % centroid of each element
      t_text = sprintf ('  %g', it);  % offset # from pt
      text (x_bar, y_bar, t_text, 'Rotation', 45) % incline
    end % for all polygons
  end % if show labels
%       -depsc -tiff            % for an eps version
  %b print -dpsc deformed_mesh_plot
  hold off
  %b fprintf ('Created file deformed_mesh_plot.ps \n')
% end of mode_2d_mesh_plot