步小昆 发表于 2015-6-9 16:29 
意思是Y=x1+x2,现在差分是diff(Y)=DIFF(x1)+diff(X2)吗??
?diff()试下
x
a numeric vector or matrix containing the values to be differenced.
lag
an integer indicating which lag to use.
differences
an integer indicating the order of the difference.
...
further arguments to be passed to or from methods.
lag是滞后阶数,differences是差分数....