% plot list of edges, given as  n by 2 array, with 
% positions given in 2 column array.

function   plot_comp(list,edges,verts,color)
   for k=1:length(list)
       v1=edges(list(k),1);
       x(k)=verts(v1,1);
       y(k)=verts(v1,2);
   end % for k
   x=[x,x(1)];
   y=[y,y(1)];
   fill(x,y,color);
return
