diff ema 的金叉和死叉時，記錄下當時K線的收盤價，怎么表示？

VARIABLE:a:=0,b:=0;

DIFF :=EMA(CLOSE,S) - EMA(CLOSE,P);
DEA  :=EMA(DIFF,M);
MACD :=2*(DIFF-DEA);

aa:cross(diff,dea);
bb:cross(dea,diff);
if aa then
a:=close;
if bb then
b:=close;