function  node_graph_result (i_p, start, stop, inc)
% Copyright 2000, J.E. Akin.  All rights reserved.
%  ------------------------------------------------------
%  Matlab graph of i_p-th component value at mesh node numbers
%   If i_p = 0, show RMS value
%  ------------------------------------------------------

% 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

  fprintf ('Begin component value graph: \n')
  if ( nargin == 0 )
    i_p = 0 ;
  end % if no arguments

  load node_results.tmp
  nr = size (node_results, 1);
  np = nr ;
  if ( nr == 0 )
    error ('Error missing file node_results.tmp')
  end % if error
  max_p = size (node_results, 2) ; % number of columns
  fprintf ('Read %g nodal solution values \n', nr)
  fprintf ('     with %g components each \n', max_p)
  if ( i_p > max_p ) 
    error ('i_p > available data')
  end % if error

  x = [1:np] ;  % node numbers only           
  if ( nargin == 0 | nargin == 1 )
    start = 1 ; stop = np ; inc = 1 ;
  elseif ( nargin == 2 )
    stop = np ; inc = 1 ;
  elseif ( nargin == 3 )
    inc = 1 ;
  end % if argument count

  if ( i_p >= 1 )
    y = node_results(:, i_p) ;
  else % i_p = 0, get root mean sq
    for k = 1:np
      y (k) = sqrt ( sum (node_results (k, 1:max_p).^2)) ;
    end % for k
  end % if get RMS value

%    Cite max, min values
  [V_X, L_X] = max (y(start:inc:stop)) ;
  [V_N, L_N] = min (y(start:inc:stop)) ;
  L_X = start - 1 + L_X ;
  L_N = start - 1 + L_N ;
  fprintf ('Max value in range is %g at node %g \n', V_X, L_X)
  fprintf ('Min value in range is %g at node %g \n', V_N, L_N)
  [V_X, L_X] = max (y) ;
  [V_N, L_N] = min (y) ;
  fprintf ('Max value is %g at node %g \n', V_X, L_X)
  fprintf ('Min value is %g at node %g \n', V_N, L_N)

%    Initialize plots
   xmax = max (x(start:inc:stop))      ; xmin = min (x(start:inc:stop)) ;
   ymax = max (y(start:inc:stop))      ; ymin = min (y(start:inc:stop)) ;
   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 (['Node Numbers, ', int2str(start),':', int2str(inc), ...
            ':', int2str(stop)])
   if ( i_p >= 1 )
     title(['FEA Solution Component\_', int2str(i_p),':   ', ...
            int2str(np),' Nodes'])
            %b int2str(nt),' Elements, ', int2str(np),' Nodes'])
     ylabel (['Component ', int2str(i_p), ' (max = ', ...
     num2str(V_X), ', min = ', num2str(V_N), ')'])
   else % i_p = 0, get root mean sq
     title(['FEA RMS\_value:  ', int2str(np),' Nodes'])
     ylabel (['FEA Solution RMS Value (max = ', ...
     num2str(V_X), ', min = ', num2str(V_N), ')'])
   end % if get RMS value

% plot graph vs node number
  plot (x(start:inc:stop), y(start:inc:stop), 'k-')
  if ( inc > 1 )
    plot (x(start:inc:stop), y(start:inc:stop), 'r+')
  end % if
% mark every 20th node    
  if ( np > 20 )
    count = 0 ;
    for i = start:inc:stop
      count = count + 1 ;
      if ( count == 20 )  
        count = 0 ;
        plot (x(i), y(i), 'k*')
      end % if
    end % for all
  end % if
  grid
 
% label max min points 
  v_text = sprintf ('---min') ;
  text  (x(L_N), V_N, v_text) ;
  v_text = sprintf ('---max') ;
  text  (x(L_X), V_X, [v_text]) ;

%       -depsc -tiff            % for an eps version
  % print ('-dpsc', ['node_result_', int2str(i_p), '_graph'])
  hold off
  % v_text = ['Created node_result_', int2str(i_p), '_graph.ps'] ;
  % fprintf (1,'%s', v_text) ; fprintf (1, ' \n' )
% end of node_graph_result