varFunc(object)
object
| either an one-sided formula specifying a variance covariate, or an object inheriting from class code{varFunc}, representing a variance function structure. |
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.varFunc
, representing a variance function
structure.varFixed
, varWeights.varFunc
,
coef.varFunc
vf1 <- varFunc(~age)