Initialize.varFunc           package:nlme           R Documentation

Initialize varFunc Object

Description:

     This method initializes 'object' by evaluating its associated
     covariate(s) and grouping factor, if any is present, in 'data';
     determining if the covariate(s) need to be updated when the values
     of the coefficients associated with 'object' change; initializing
     the log-likelihood and the weights associated with 'object'; and
     assigning initial values for the coefficients in 'object', if none
     were present. The covariate(s) will only be initialized if no
     update is needed when 'coef(object)' changes.

Usage:

     ## S3 method for class 'varFunc':
     Initialize(object, data, ...)

Arguments:

  object: an object inheriting from class 'varFunc', representing a
          variance function structure.

    data: a data frame in which to evaluate the variables named in
          'formula(object)'. 

     ...: this argument is included to make this method compatible with
          the generic.

Value:

     an initialized object with the same class as 'object' representing
     a variance function structure.

Author(s):

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

See Also:

     'Initialize'

Examples:

     vf1 <- varPower( form = ~ age | Sex )
     vf1 <- Initialize( vf1, Orthodont )

