斜率交易，顾名思义。抓趋势

X1:C;
 X2:REF(X1,10);
线斜率:((X1-X2)/X2*100)*10;
斜率20日值:MA(线斜率,10);
 DRAWTEXT(CROSS(线斜率,斜率20日值),线斜率,'始');
DRAWTEXT(CROSS(斜率20日值,线斜率),斜率20日值,'终');