cumsum, but you have to add back the information lost in the diff operation by generating an extra zero at the beginning or end of the sequence and adding the appropriate offset to the resulting vector.
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Sent from my phone. Please excuse my brevity.

"Flávio Fagundes" <flavio2f@gmail.com> wrote:

Hi users.
I'm new user in R.
I'm workiing with Time series and I would like to know how can I do to undo
the command DIFF(X), for exemple:
If I have the model: m=arima(X, order=c(0,1,1),
seasonal=list(order=c(0,0,1))) (note that have d=1 one difference), to find,
in the same scale, the original numbers (like one "unDiff"), after the
forecast, I need to develop some function or in R there is some command
ready or function?
Thanks
Fl�vio

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