Initialize.varFunc           package:nlme           R Documentation

_I_n_i_t_i_a_l_i_z_e _v_a_r_F_u_n_c _O_b_j_e_c_t

_D_e_s_c_r_i_p_t_i_o_n:

     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.

_U_s_a_g_e:

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

_A_r_g_u_m_e_n_t_s:

  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.

_V_a_l_u_e:

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

_A_u_t_h_o_r(_s):

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

_E_x_a_m_p_l_e_s:

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

