请将通达信指标b点做预警

编写要求：

源码MA5:MA(CLOSE,5),COLORFFFFFF,LINETHICK2; MA13:MA(CLOSE,13),COLOR00FF00; MA21:MA(CLOSE,21),COLOR00FFFF,LINETHICK2; MA34:MA(CLOSE,34),COLORFF00FF; {MA55:MA(CLOSE,55),COLOR0000FF;} {MA120:=MA(CLOSE,120),COLORFFFF00;} 天使:=EMA(C,2),COLOR000000; 魔鬼:=EMA(SLOPE(C,21)*20+C,42),COLOR000000; 买:=CROSS(天使,魔鬼); 卖:=CROSS(魔鬼,天使); DRAWICON(买,L*0.97,1); DRAWTEXT(买,L*0.95,'B'),COLORYELLOW; DRAWICON(卖,H*1.03,2); DRAWTEXT(卖,H*1.05,'S'),COLORWHITE; STICKLINE(天使>=魔鬼,LOW,HIGH,0.01,0),COLOR0000DD; STICKLINE(天使>=魔鬼,CLOSE,OPEN,2,1),COLORRED; {STICKLINE(天使>=魔鬼,CLOSE,OPEN,3,0),COLOR0000CC; STICKLINE(天使>=魔鬼,CLOSE,OPEN,2,0),COLOR0000DD; STICKLINE(天使>=魔鬼,CLOSE,OPEN,1,0),COLOR0000FF;} {STICKLINE(天使<魔鬼,CLOSE,OPEN,1,0),COLOREEEE00; STICKLINE(天使<魔鬼,CLOSE,OPEN,2,0),COLORDDDD00; STICKLINE(天使<魔鬼,CLOSE,OPEN,3,0),COLORCCCC00;} STICKLINE(天使<魔鬼,LOW,HIGH,0.01,0),COLORFFDD00; STICKLINE(天使<魔鬼,CLOSE,OPEN,2,0),COLORFFFF00; STICKLINE(CROSS(天使,魔鬼),OPEN,CLOSE,2.5,0),COLORYELLOW; STICKLINE(CROSS(魔鬼,天使),OPEN,CLOSE,2.5,0),COLORWHITE;

解答：

 天使:=EMA(C,2);