statsmodels.sandbox.tsa.fftarma.ArmaFft.invertroots¶

ArmaFft.invertroots(retnew=False)¶

Make MA polynomial invertible by inverting roots inside unit circle.

Parameters:¶

retnew : bool¶

If False (default), then return the lag-polynomial as array. If True, then return a new instance with invertible MA-polynomial.

Returns:¶

• manew (ndarray) – A new invertible MA lag-polynomial, returned if retnew is false.

• wasinvertible (bool) – True if the MA lag-polynomial was already invertible, returned if retnew is false.

• armaprocess (new instance of class) – If retnew is true, then return a new instance with invertible MA-polynomial.