dse (version 2020.2-1)

toSS: Convert to State Space Model

Description

Convert a model to state space form.

Usage

toSS(model, ...)
    # S3 method for ARMA
toSS(model, ...)
    # S3 method for SS
toSS(model, ...)
    # S3 method for TSestModel
toSS(model, ...)
    
    toSSaugment(model, ...)
    # S3 method for ARMA
toSSaugment(model, fuzz=1e-14, ...)
    # S3 method for TSestModel
toSSaugment(model, ...)
    
    toSSnested(model, ...)
    # S3 method for ARMA
toSSnested(model, n=NULL, Aoki=FALSE, ...)
    # S3 method for SS
toSSnested(model, n=NULL, Aoki=FALSE, ...)
    # S3 method for TSestModel
toSSnested(model, ...)

Arguments

model

An object of class TSmodel.

n

If n is specified then it is used as the state dimension when the markov parameter conversion technique is required.

Aoki

logical indicating if Aoki's method (which does not work in general) should be tried.

fuzz

if the zero lag term of polynomials A and B are within fuzz of the identitity matrix then they are not inverted. (i.e. they are assumed to be identity.)

...

arguments to be passed to other methods.

Value

A state space model in an object of class 'SS' 'TSmodel'.

Details

If the order of the AR polynomial equals or exceeds the MA polynomial (and the input polynomial) then the model is converted by state augmentation. Otherwise, it is converted by approximating the markov coefficients a la Mittnik. (This may not always work very well. Compare the results to check.)

Examples

# NOT RUN {
data("eg1.DSE.data.diff", package="dse")
model <- estVARXls(eg1.DSE.data.diff)
model <- toSS(model)
# }