nlme (version 3.1-38)

formula.varFunc: Extract varFunc Formula

Description

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

Usage

## S3 method for class 'varFunc':
formula(x, \dots)

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.

Examples

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