This function is generic; method functions can be written to handle
specific classes of objects. Classes which already have methods for
this function include all "varFunc" classes,
see ‘varClasses’.
covariate(object) <- valuewill depend on the method function; see the appropriate documentation.
any object with a covariate component.
a value to be assigned to the covariate associated with
object.
José Pinheiro and Douglas Bates bates@stat.wisc.edu
covariate<-.varFunc, getCovariate