coef.pdMat               package:nlme               R Documentation

pdMat Object Coefficients

Description:

     This method function extracts the coefficients associated with the
     positive-definite matrix represented by 'object'.

Usage:

     ## S3 method for class 'pdMat':
     coef(object, unconstrained, ...)
     ## S3 replacement method for class 'pdMat':
     coef(object, ...) <- value

Arguments:

  object: an object inheriting from class 'pdMat', representing a
          positive-definite matrix.

unconstrained: a logical value. If 'TRUE' the coefficients are returned
          in unconstrained form (the same used in the optimization
          algorithm). If 'FALSE' the upper triangular elements of the
          positive-definite matrix represented by 'object' are
          returned. Defaults to 'TRUE'.

   value: a vector with the replacement values for the coefficients
          associated with 'object'. It must be a vector with the same
          length of 'coef{object}' and must be given in unconstrained
          form.

     ...: some methods for this generic require additional arguments. 
          None are used in this method.

Value:

     a vector with the coefficients corresponding to 'object'.

SIDE EFFECTS:

     On the left side of an assignment, sets the values of the
     coefficients of 'object' to 'value'.

Author(s):

     Jose Pinheiro and Douglas Bates

References:

     Pinheiro, J.C. and Bates., D.M.  (1996) "Unconstrained
     Parametrizations for Variance-Covariance Matrices", Statistics and
     Computing, 6, 289-296.

See Also:

     'pdMat'

Examples:

     coef(pdSymm(diag(3)))

