编写要求：
1.DMI指标 PDI小于10 MDI大于40 ADX大于50 ADXR大于40 2.最低价比前两天低 3.成交量比前两天低
公式在线网解答：
"DMI.PDI"<=10 AND "DMI.MDI">40 AND "DMI.ADX">50 AND "DMI.ADXR">40 AND L<REF(L,1) AND L<REF(L,2) AND V<REF(V,1) AND V<REF(V,2);
