

pdMat(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

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

     This function gives an alternative way of constructing
     an object inheriting from the `pdMat' class named in
     `pdClass', or from `data.class(object)' if `object'
     inherits from `pdMat',  and is mostly used internally
     in other functions. See the documentation on the prin-
     cipal constructor function, generally with the same
     name as the `pdMat' class of object.

_U_s_a_g_e_:

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

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

   value: an optional initialization value, which can be any
          of the following: a `pdMat' object, a positive-
          definite matrix, a one-sided linear formula (with
          variables separated by `+'), a vector of character
          strings, or a numeric vector. Defaults to
          `numeric(0)', corresponding to an uninitialized
          object.

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

     nam: an optional vector of character strings specifying
          the row/column names for the matrix represented by
          object. It must have length equal to the dimension
          of the underlying positive-definite matrix and
          unreplicated elements. This argument is ignored
          when `value' is a 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 `factors' appearing in
          the formulas. Defaults to the parent frame from
          which the function was called.

 pdClass: an optional character string naming the `pdMat'
          class to be assigned to the returned object. This
          argument will only be used when `value' is not a
          `pdMat' object. Defaults to `"pdSymm"'.

_V_a_l_u_e_:

     a `pdMat' object representing a positive-definite
     matrix, inheriting from the class named in `pdClass',
     or from `class(object)', if `object' inherits from
     `pdMat'.

_A_u_t_h_o_r_(_s_)_:

     Jose Pinheiro and Douglas Bates

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

     `pdCompSymm', `pdDiag', `pdIdent', `pdNatural',
     `pdSymm'

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

     library(nlme)
     pd1 <- pdMat(diag(1:4), pdClass = "pdDiag")
     pd1

