Extract varFunc Formula

Usage

formula(object)

Arguments

object an object inheriting from class code{varFunc}, representing a variance function structure.

Description

This method function extracts the formula associated with a varFunc object, in which covariates and grouping factors are specified.

Value

if object has a formula attribute, its value is returned; else NULL is returned.

Author(s)

Jose Pinheiro and Douglas Bates

Examples

library(lme)
formula(varPower(form = ~ fitted(.) | Sex))

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