Method for filtering an ARFIMA model.

`arfimafilter(spec, data, out.sample = 0, n.old=NULL, ...)`

data

A univariate data object. Can be a numeric vector, matrix, data.frame, zoo, xts, timeSeries, ts or irts object.

spec

out.sample

A positive integer indicating the number of periods before
the last to keep for out of sample forecasting (as in `arfimafit`

function).

n.old

For comparison with ARFIMA models using the out.sample argument, this is the length of the original dataset (see details).

...

.

A `'>ARFIMAfilter`

object containing details of the ARFIMA
filter.

The n.old argument is optional and indicates the length of the original data (in cases when this represents a dataseries augmented by newer data). The reason for using this is so that the old and new datasets agree since the original recursion uses the sum of the residuals to start the recursion and therefore is influenced by new data. For a small augmentation the values converge after x periods, but it is sometimes preferable to have this option so that there is no forward looking information contaminating the study.