Sounds like a homework problem...
In general, the AR or MA representation of an ARMA process will be of
infinite order.
GP
> Date: Tue, 04 Nov 2008 07:10:03 -0800 (PST)
> From: "poolloopus at yahoo.com" <poolloopus at yahoo.com>
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> Hi,
>
> I am new to using R for Time series analysis. I was wondering if there are
any functions that can convert ARMA or ARIMA time series into their
corresponding AR or MA time series representations (by calculating the
corresponding AR or MA coefficients).
>
> Thanks a lot
>
> Kris.
>
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--
Giovanni Petris <GPetris at uark.edu>
Associate Professor
Department of Mathematical Sciences
University of Arkansas - Fayetteville, AR 72701
Ph: (479) 575-6324, 575-8630 (fax)
http://definetti.uark.edu/~gpetris/