BOLL:=MA(CLOSE,20);UB:=BOLL+2*STD(CLOSE,20);LB:=BOLL-2*STD(CLOSE,20);boll>=ref(boll,1) and c>=boll and l<=boll;
布林线上行,调整到中轨的选股公式 详细请参照 http://wenku.baidu.com/view/a97fe95c6137ee06eef9180f
