关于内建函数XAverage应该怎么理解？

翻看了XAverage的源码： Params Numeric Price(10); //数值型序列值 Numeric Length(10); //周期数 Vars Numeric sFcactor; Series<Numeric> XAvgValue; Begin sFcactor = 2 / ( Length + 1 ); if (CurrentBar == 0 ) { XAvgValue = Price; }else { XAvgValue = XAvgValue[1] + sFcactor * ( Price - XAvgValue[1] ) ; } Return XAvgValue; End 问题如下： 1.求老师告知， XAvgValue = XAvgValue[1] + sFcactor * ( Price - XAvgValue[1] )这段应该怎么理解？ 2.XAvgValue 和 Average 有啥区别？ 3.XAverage(TrueRange,ATRLength)与 AvgTrueRange(Numeric Length) 有什么区别？