R help - Feb 2008 - Nonlinear autoregression and spectral analysis (mixed spectra)

Hi,

 

I am studying frequency the seasonal cycle of a time-series that I believe
includes also an AR (1) component.  I would be interested in estimating
frequency, amplitude and phase of the main seasonal cycle of the parameter
of the AR component. I have preliminary estimates of the seasonal parameters
(based on nls fitting of amplitude*cos(frequency*t-phase) assuming iid
errors) and of the AR parameter (based on ar.yw of the data). I would
however like to fit both components simultaneously since they confound each
other if estimated separately (resembling a mixed spectrum problem).

 

Is there a function in R that allows an autoregressive component to be
included in a nonlinear (on frequency) regression? Alternatively
(additionally), is there any package handling mixed spectrum estimation? 

 

Thanks in advance for any suggestions,

 

Nuno

 

 ______________________________________________ 

Instituto de Oceanografia - FCUL, Portugal

Center for Quantitative Fisheries Ecology - ODU, USA


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