If object is a one-sided formula, it is used as the argument to
varFixed and the resulting object is returned. Else, if
object inherits from class varFunc, it is returned
unchanged.
Usage
varFunc(object)
Arguments
object
either an one-sided formula specifying a variance
covariate, or an object inheriting from class varFunc,
representing a variance function structure.
Value
an object from class varFunc, representing a variance function
structure.