pdClasses                package:nlme                R Documentation

_P_o_s_i_t_i_v_e-_D_e_f_i_n_i_t_e _M_a_t_r_i_x _C_l_a_s_s_e_s

_D_e_s_c_r_i_p_t_i_o_n:

     Standard classes of positive-definite matrices ('pdMat')
     structures  available in the 'nlme' library.

_V_a_l_u_e:

     Available standard classes: 

  pdSymm: general positive-definite matrix, with no additional
          structure

pdLogChol: general positive-definite matrix, with no additional
          structure, using a log-Cholesky parameterization

  pdDiag: diagonal

 pdIdent: multiple of an identity

pdCompSymm: compound symmetry structure (constant diagonal and constant
          off-diagonal elements)

pdBlocked: block-diagonal matrix, with diagonal blocks of any "atomic"
          'pdMat' class

pdNatural: general positive-definite matrix in natural parametrization
          (i.e. parametrized in terms of standard deviations and
          correlations). The underlying coefficients are not
          unrestricted, so this class should NOT be used for
          optimization.

_N_o_t_e:

     Users may define their own 'pdMat' classes by specifying a
     'constructor' function and, at a minimum, methods for the
     functions 'pdConstruct', 'pdMatrix' and 'coef'. For examples of
     these functions, see the methods for classes 'pdSymm' and
     'pdDiag'.

_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:

     'pdCompSymm', 'pdDiag', 'pdIdent', 'pdNatural', 'pdSymm',
     'pdLogChol'

