ii := 0;
   FOR i := 1 TO Nx DO
      IF open[i]<0.5 THEN
      BEGIN
	 ii := ii+1;
	 xnew[i] := xsub[ii];
      END ELSE
	 xnew[i] := x[i];
	 xnew[i] := 0.0;
END;{mtt_implicit}