function  quiver_fiber_heat_flux_mesh (scale, inc_g, wide, sign) 
% default (1.0, 1, 1)
% Copyright 2000, J.E. Akin.  All rights reserved.
%  ------------------------------------------------------
%  Matlab plot of 2-D FE flux vectors at elem Gauss pts, with mesh
%  ------------------------------------------------------

% c_x    = x coordinates of nod_per_el wide polygon
% c_y    = y coordinates of nod_per_el wide polygon
% inc_e  = increment in element numbers on plot, if > 0
% inc_g  = increment in Gauss point vector plot, default = 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 wide polygon
% lab_p  = 1, if node points are circled
  lab_p  = 0;
% length = maximum length of arrows, in scaled x,y units
% 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_p  = 1 ;
% msh_bc_xyz = Nodal coordinates (with preceeding data)
% scale  = standard Matlab scale argument, default 1.0
% t_x    = x coordinates of nod_per_el corners
% t_y    = y coordinates of nod_per_el corners
%b  % x_bar  = x-centroid of each element
% xy     = Coordinates of points, np x 2
%b  % y_bar  = y-centroid of each element

%                set constants
  if ( nargin == 0 )
    scale = 1.  ;   % the default scale      
    inc_g = 1 ; wide = 2 ; sign = 1 ;
  elseif ( nargin == 1 )
    inc_g = 1 ; wide = 2 ; sign = 1 ;
  elseif ( nargin == 2 )
    wide = 2 ; sign = 1 ;
  elseif ( nargin == 3 )
    sign = 1 ;
  end % if
  fprintf ('Using a scale of %g and vector increment of %g \n', ...
            scale, inc_g)
  format short 

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

%    Set control data: number of points
  np = size (msh_bc_xyz,1) ;   % number of nodal points  
  ns = size (msh_bc_xyz,2) - 1;   % dimension of space      
  fprintf ('Read %g mesh coordinates \n', np)
  fprintf ('In %g spatial dimensions \n', ns)
% fprintf ('       x        y \n')
  
%    Set control data: number elements
  load  msh_typ_nodes.tmp ;              % nod_per_el nodes per element
  nt = size (msh_typ_nodes,1) ;          % number of elements in mesh 
  pre_e  = 0 ;
  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
  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

%    Mesh Range Alone
  % 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

  gxmax = max (x)      ; gxmin = min (x) ;
  gymax = max (y)      ; gymin = min (y) ;
  gxdiff = gxmax - gxmin ; gydiff = gymax - gymin ;
  if ( gydiff == 0.0 )
    gydiff = 0.5 ; % allow for 1-D mesh (with y == 0)
  end % if no y coordinates

  xmax = gxmax + gxdiff/20 ; ymax = gymax + gydiff/20 ;
  xmin = gxmin - gxdiff/20 ; ymin = gymin - gydiff/20 ;

  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 for ', int2str(nt),' Elements with ', ...
          int2str(nod_per_el), ' nodes'])
  ylabel (['Y; for ', int2str(np),' Nodes'])
  title  (['    Nanofiber Heat Flux Vectors with Mesh'])
%  if ( inc_g == 1 )
%    title  (['    Heat Flux Vectors (max = ', ...
%            num2str(largest),') with Nanofibers']) % add title
%  else
%    title  (['   Heat Flux Vectors at ', int2str(npg), ...
%            ' Gauss Pts, inc = ', int2str(inc_g), ...
%            ', max = ', num2str(largest)]) % add title
%  end % if alternate title

%      Select element type details
  [loop] = get_El_Loop (nod_per_el) ;

%%      Plot input mesh points & label them
%  if (lab_p == 1)                   % plot all points
%    plot (x, y, 'b.')               % mark each node
%  end % if show labels

%    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

%      Plot this polygon
    c_x  = t_x (loop) ;       % x for nod_per_el wide polygon
    c_y  = t_y (loop) ;       % y for nod_per_el wide polygon
    plot (c_x, c_y, 'b-')     % plot nod_per_el wides, in blue
  end % for over all elements
 
%  ---------------- Now add the vectors to the mesh --------------
  %b quiver (g_x, g_y, g_dx, g_dy, scale)

% now overlay the fibers
%b fiber_loc_overlay (xmin, xmax, ymin, ymax, wide)
fiber_heat_flux_overlay (xmin, xmax, ymin, ymax, scale, wide)

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