Driver function for dhare, hhare, phare, qhare,
and rhare. This function is not intended for use by itself.
xhare(arg1, arg2, arg3, arg4)arguments.
This function is used internally.
Charles Kooperberg, Charles J. Stone and Young K. Truong (1995). Hazard regression. Journal of the American Statistical Association, 90, 78-94.
Charles J. Stone, Mark Hansen, Charles Kooperberg, and Young K. Truong. The use of polynomial splines and their tensor products in extended linear modeling (with discussion) (1997). Annals of Statistics, 25, 1371--1470.