编写要求：
MACD零轴上第一次死叉的选股公式
公式在线网解答：
DIFF:="MACD.DIFF"(26,12,9); DEA:="MACD.DEA"(26,12,9); 上穿:=BARSLAST(CROSS(DIFF,0))+1; TJ1:=COUNT(DIFF>DEA AND DIFF>0,上穿)=上穿; TJ2:=CROSS(DEA,DIFF) AND DIFF>0; XG:REF(TJ1,1) AND TJ2;
