function  dof_time_hist 
% Copyright 2004, J.E. Akin.  All rights reserved.
%  ------------------------------------------------------
%  Matlab time-history of value at sys DOF  
%  ------------------------------------------------------

% c_x    = x coordinates of nod_per_el line element
% msh_typ_nodes   = connectivity list for elements, nt x nod_per_el
% loop   = corners for nod_per_el line element
% 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

  load dof_history.tmp ;  

%    Set control data: number of points
  np = size (dof_history,1) ;   % number of nodal points  
  fprintf ('Read %g time-history sets \n', np)
  max_p = size (dof_history,2) - pre_p -1 ;   % space dimension
  fprintf ('with %g nodal dof values  \n', max_p)
  dof  = dof_history (1, 1) ;
  fprintf ('for dof number %g \n', dof)

  x (np)      = 0.       ;       % pre-allocate array x
  y (np)      = 0.       ;       % pre-allocate array y
  
  x = dof_history (1:np, 2)  ; % extract x column
  y = dof_history(:, 3)     ;

%    Cite max, min values
  [V_X, L_X] = max (y) ;
  [V_N, L_N] = min (y) ;
  fprintf ('Max value is %g at step %g \n', V_X, (L_X-1))
  fprintf ('Min value is %g at step %g \n', V_N, (L_N-1))
  null (1:np) = V_N ;

%    Initialize plots
   xmax = max (x)      ; xmin = min (x) ;
   ymax = max (y)      ; ymin = min (y) ;
   if ( ymax == ymin )
     if ( abs (ymax) > 0 )
       ymax = ymax + abs (ymax)/20. ;
       ymin = ymin - abs (ymin)/20. ;
     end % if
   end % if

   clf                               % clear graphics
   axis ([xmin, xmax, ymin, ymax])   % set axes

   hold on                           % hold image for plots
   xlabel ('Time')
   title(['FEA Time-History for Degree of Freedom ', ...
           int2str(dof)'])
   ylabel (['DOF Value  (max = ', ...
   num2str(V_X), ', min = ', num2str(V_N), ')'])

% plot dof values         
   plot (x, y, 'k-')
   plot (x, y, 'ko')
  grid
 
% label max min points 
  %b v_text = sprintf ('---min') ;
  %b text  (x(L_N), V_N, v_text) ;
  %b v_text = sprintf ('---max') ;
  %b text  (x(L_X), V_X, [v_text]) ;

%       -depsc -tiff            % for an eps version
  hold off
% end of dof_time_hist