      load "splitedges"
      mesh Th=square(50,50);
      real xx=1.1,yy=1.1;	
      for(int i=0;i<4;++i)
	{     
	  xx *= 0.5;
	  yy *= 0.5;
	  Th=SplitEdgeMesh(Th,x<yy && y < yy );
	  plot(Th,wait=1);
	}
