nn1:=barslast(j>n);

nn2:=barslast(j<n);

hh1:ref(hhv(h,nn2+1),nn1);

hh2:ref(hhv(h,nn1+1),nn2);

if nn1>nn2 then hh:=hh2;

if nn1<nn2 then hh:=hh1;

hh是所求值