

   CCoommbbiinnaattiioonn ooff VVaarriiaannccee FFuunnccttiioonnss

        varComb(...)

   AArrgguummeennttss::

        ...: objects inheriting from class `varFunc' represent-
             ing variance function structures.

   DDeessccrriippttiioonn::

        This function is a constructor for the `varComb' class,
        representing a combination of variance functions. The
        corresponding variance function is equal to the product
        of the variance functions of the `varFunc' objects
        listed in `...'.

   VVaalluuee::

        a `varComb' object representing a combination of vari-
        ance functions, also inheriting from class `varFunc'.

   AAuutthhoorr((ss))::

        Jose Pinheiro and Douglas Bates

   SSeeee AAllssoo::

        `varWeights.varComb', `coef.varComb'

   EExxaammpplleess::

        library(lme)
        vf1 <- varComb(varIdent(form = ~1|Sex), varPower())

