A vector is returned consisting of the asymtpotic F-value,
the associated numerator and denominator d.f.'s and
asymptotic p.val for the test of linearity
Details
This is the Tukey one-degree-of-freedom test of linearity
developed by Tsay (1986). Orders up to 5 is
permissible. [although the code is easily extended].
References
Tsay, R.S. (1986) Nonlinearity tests for time series. Biometrika, 73, 461-466.