function  smooth_qp_source_component (i_p)
% Copyright 2000 J.E. Akin. All rights reserved.
% plot finite element nodal flux magnitude as a surface 
% convert any type of mesh to a structured square mesh
% plot of i_p-th component. If i_p = 0, show RMS

% x,y   ==  nodal coordinates of the FEA
% f     ==  nodal solution of the FEA
% X,Y   ==  nodal coordinates of the structured square mesh
% F     ==  interpolated solution for the structured square mesh
% NX    ==  number of nodes in x-direction for structured mesh 
% NY    ==  number of nodes in y-direction for structured mesh

if ( nargin == 0 )
  i_p = 0 ;
end % if no arguments
 
load el_qp_xyz_sources.tmp; % x,y followed by flux list
np = size (el_qp_xyz_sources, 1) ;     % count points
nf = size (el_qp_xyz_sources, 2) - 2;  % count components
if ( np == 0 )
  error ('Error missing file el_qp_xyz_sources.tmp')
end % if error
if ( nf <= 0 )
  error ('Error, no fluxes in file el_qp_xyz_sources.tmp')
end % if error

% NX, NY = 31 are default values, these can be altered by user
NX = 61; NY = 61;

x = el_qp_xyz_sources (:, 1); y = el_qp_xyz_sources (:, 2);
% disp (x) ; disp (y)
 
if ( i_p > 0 )
  f =  el_qp_xyz_sources (:, (i_p + 2)) ;
else
  for j = 1:np
    f(j) = sqrt ( sum(el_qp_xyz_sources (j, 3:(nf+2)).^2) ) ;
  end % for np points
end % which component

xlin = linspace (min(x), max(x), NX);
ylin = linspace (min(y), max(y), NY);
[X, Y] = meshgrid (xlin, ylin);
F = griddata (x, y, f, X, Y, 'cubic');

clf
meshc (X, Y, F)
hold on
xlabel ('X'); ylabel ('Y');
if ( i_p > 0 )
  title (['Matlab Smoothed FEA QP Source Component\_', ...
   int2str(i_p), ': at ',int2str(np),' Gauss Points'])
  zlabel (['FEA Source Component ', int2str(i_p)]);
else
  title (['Matlab Smoothed FEA RMS QP Source Value: at ', ...
           int2str(np),' Gauss Points'])
  zlabel ('FEA Source RMS Value');
end % which component

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