Convert varFunc Object to Natural Parameterization
DESCRIPTION:
This method function converts
object
to another
varFunc
object represented in a natural
parameterization. If
unconstrained
is set to
TRUE
, the
natural unconstrained parameterization used is the same as the one
used for
object
, which is returned unchanged. If
unconstrained
is set to
FALSE
, a constrained natural
parameterization is used to represent the object. In this case, a
constructor with the name
Nat
appended to the end of the
original
object
constructor is called (e.g.,
varPowerNat
is called for
varPower
objects).
varFunc
objects with
constrained natural parameterization are represented by the
coefficients returned by
coef(object, uncons = FALSE)
.
USAGE:
asNatural(object, unconstrained)
REQUIRED ARGUMENTS:
- object
-
an object inheriting from class
varFunc
,
representing a variance function structure, whose
representation is to be converted to a natural parameterization.
OPTIONAL ARGUMENTS:
- unconstrained
-
an optional logical value indicating whether the
natural parameterization should be unconstrained. Defaults to
TRUE
.
VALUE:
If
unconstrained = TRUE
,
object
is returned unchanged,
else, if
unconstrained = FALSE
, a
varFunc
object
parameterized according to the constrained coefficients
corresponding to
object
- the class corresponding to these
objects is obtained by appending the name
Nat
to the end of
the original class of
object
.
EXAMPLES:
vf1 <- varConstPower(2, 0.5, form = ~age)
vf1 <- initialize(vf1, data = Orthodont)
asNatural(vf1, unc = F)