pdBlocked                package:nlme                R Documentation

_P_o_s_i_t_i_v_e-_D_e_f_i_n_i_t_e _B_l_o_c_k _D_i_a_g_o_n_a_l _M_a_t_r_i_x

_D_e_s_c_r_i_p_t_i_o_n:

     This function is a constructor for the `pdBlocked' class,
     representing a positive-definite block-diagonal matrix. Each
     block-diagonal element of the underlying  matrix is itself a
     positive-definite matrix and is represented internally as an
     individual `pdMat' object. When `value' is `numeric(0)', a list of
     uninitialized `pdMat' objects, a list of one-sided formulas, or a
     list of vectors  of character strings,  `object' is returned as an
     uninitialized `pdBlocked' object (with just some of its attributes
     and its class defined) and needs to have its coefficients assigned
     later, generally using the `coef' or `matrix' replacement
     functions. If `value' is a list of  initialized `pdMat' objects,
     `object' will be constructed from the list obtained by applying
     `as.matrix' to each of the `pdMat' elements of `value'. Finally,
     if `value' is a list of numeric vectors, they are assumed to
     represent the unrestricted coefficients of the block-diagonal
     elements of the  underlying positive-definite matrix.

_U_s_a_g_e:

     pdBlocked(value, form, nam, data, pdClass)

_A_r_g_u_m_e_n_t_s:

   value: an optional list with elements to be used as the `value'
          argument to other `pdMat' constructors. These include:
          `pdMat' objects, positive-definite matrices, one-sided linear
          formulas, vectors of character strings, or numeric vectors.
          All elements in the list must be similar (e.g. all one-sided
          formulas, or all numeric vectors). Defaults to `numeric(0)',
          corresponding to an uninitialized object.

    form: an optional list of one-sided linear formulas specifying the
          row/column names for the block-diagonal elements of the
          matrix represented by `object'. Because factors may be
          present in `form', the formulas needs to be evaluated on a
          data.frame to resolve the names they define. This argument is
          ignored when `value' is a list of one-sided formulas.
          Defaults to `NULL'.

     nam: an optional list of vector of character strings specifying
          the row/column names for the block-diagonal elements of the
          matrix represented by object. Each of its components must
          have   length equal to the dimension of the corresponding
          block-diagonal element and unreplicated elements. This
          argument is ignored when  `value' is a list of vector of
          character strings. Defaults to  `NULL'.

    data: an optional data frame in which to evaluate the variables
          named in `value' and `form'. It is used to obtain the levels
          for `factors', which affect the dimensions and the row/column
          names of the underlying matrix. If `NULL', no attempt is made
          to obtain information on any `factors' appearing in the
          formulas. Defaults to the parent frame from which the
          function was called.

 pdClass: an optional vector of character strings naming the `pdMat'
          classes to be assigned to the individual blocks in the
          underlying matrix. If a single class is specified, it is used
          for all block-diagonal elements. This argument will only be
          used when `value' is missing, or its elements are not `pdMat'
          objects. Defaults to `"pdSymm"'.

_V_a_l_u_e:

     a `pdBlocked' object representing a positive-definite
     block-diagonal matrix, also inheriting from class `pdMat'.

_A_u_t_h_o_r(_s):

     Jose Pinheiro and Douglas Bates

_S_e_e _A_l_s_o:

     `as.matrix.pdMat', `coef.pdMat', `matrix<-.pdMat'

_E_x_a_m_p_l_e_s:

     pd1 <- pdBlocked(list(diag(1:2), diag(c(0.1, 0.2, 0.3))),
                      nam = list(c("A","B"), c("a1", "a2", "a3")))
     pd1

