R help - Feb 2009 - TAR Models and predictive residuals

Hello R users.

There is a paper from Ruey Tsay with the title: "Testing and Modelling
Threshold Autoregressive Processes", published in 1989 in the Journal of
the American Statistical Association (March, Vol. 84, No. 405).

Mr. Tsay describes a very interesting way of identifying and modelling threshold
AR processes.

1. Is there a package in R or some routines, which implements his ideas and his
methodology?

2. Is there a routine in R to calculate the predictive residuals (like defined
in the paper)?


Thanks in advance.

Regards,
Andreas.