编写要求：
MACD顶背离的选股预警公式指标。
www.gszx.com.cn网解答：
DIFF:=EMA(CLOSE,12)-EMA(CLOSE,26); DEA:=EMA(DIFF,9); MACD:=(DIFF-DEA)*2; B:=BARSLAST(REF(CROSS(DEA,DIFF),1)); 顶背:REF(H,B+1)<H AND DIFF<REF(DIFF,B+1) AND CROSS(DEA,DIFF);
