原理：牛股是从20线开始的。还有用Skd限制了一下。

N 2 90 9 M 3 30 3
LOWV:=LLV(LOW,N);
HIGHV:=HHV(HIGH,N);
RSV:=EMA((CLOSE-LOWV)/(HIGHV-LOWV)*100,M);
K:=EMA(RSV,M);
D:=MA(K,M);
B:=K D OR crOSS(k,d);
A:=CROSS(C,MA(C,20)) or (O MA(C,20) AND C MA(C,20) );
发财:a and b;