Checks if a MixAR model is stable. This is also the second
order stationarity condition.
Details
If each component of a MixAR model corresponds to a stable
autoregression model, then the MixAR model is also stable. However,
the MixAR model may be stable also when some of its components
correspond to integrated or explosive AR models, see the references.
Value
True if the model is stable (second order stationary), FALSE otherwise.
References
Boshnakov2011on1st2ndmixAR
WongLi2000mixAR
Examples
isStable(exampleModels$WL_I)
#> [1] TRUE
isStable(exampleModels$WL_II)
#> [1] TRUE