pdFactor.reStruct            package:nlme            R Documentation

_E_x_t_r_a_c_t _S_q_u_a_r_e-_R_o_o_t _F_a_c_t_o_r _f_r_o_m _C_o_m_p_o_n_e_n_t_s _o_f _a_n _r_e_S_t_r_u_c_t _O_b_j_e_c_t

_D_e_s_c_r_i_p_t_i_o_n:

     This method function extracts square-root factors of the
     positive-definite matrices corresponding to the 'pdMat' elements
     of 'object'.

_U_s_a_g_e:

     ## S3 method for class 'reStruct':
     pdFactor(object)

_A_r_g_u_m_e_n_t_s:

  object: an object inheriting from class 'reStruct', representing a
          random effects structure and consisting of a list of 'pdMat'
          objects.

_V_a_l_u_e:

     a vector with square-root factors of the positive-definite
     matrices corresponding to the elements of 'object' stacked
     column-wise.

_N_o_t_e:

     This function is used intensively in optimization algorithms and
     its value is returned as a vector for efficiency reasons. The
     'pdMatrix' function can be used to obtain square-root factors in
     matrix form.

_A_u_t_h_o_r(_s):

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

_S_e_e _A_l_s_o:

     'pdMatrix.reStruct', 'pdFactor.pdMat'

_E_x_a_m_p_l_e_s:

     rs1 <- reStruct(pdSymm(diag(3), ~age+Sex, data = Orthodont))
     pdFactor(rs1)

