formula.varFunc {nlme}R Documentation

Extract varFunc Formula

Description

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

Usage

formula(x, ...)

Arguments

x an object inheriting from class varFunc, representing a variance function structure.
... some methods for this generic require additional arguments. None are used in this method.

Value

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

Author(s)

Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu

Examples

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

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