oV := BackupSystemParameters2();
   //假设组合为申万采掘，先计算其下个股的区间收益率
  stockArr := getbk('申万采掘');
  BegT := inttodate(20110101);
  EndT := inttodate(20110630);
  t := array();
  n := 0;
  for i:=0 to length(stockArr)-1 do
  begin
   stockid := stockArr[i];
   setsysparam(pn_stock(),stockid);
   if not IsStockGoMarket(begt) then continue;
   tmp := stockzf(BegT,EndT);
   t[n]['代码'] := stockid;
   t[n]['名称'] := stockname(stockid);
   t[n]['涨幅(%)'] := tmp;
   n++;
  end
   //按总股本加权，计算组合收益率
  t2 := pf_percent(t[:,'代码'],EndT,0);
  t := select [1].['涨幅(%)'],[2].['比例(%)'] from t
     left join t2 with([1].['代码'] on [2].['代码'])
     end;
  return StocksExpectedReturn(t[:,'涨幅(%)'],t[:,'比例(%)']); //结果：3.8980