Convert corStruct Object to Natural Parameterization

DESCRIPTION:

This method function converts object to another corStruct 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. The exceptions are the corSymm and corBand classes (see the documentation on the appropriate asNatural method). 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., corAR1Nat is called for corAR1 objects). corStruct objects with constrained natural parameterization are represented by the coefficients returned by coef(object, uncons = FALSE), except for corSymm and corBand objects (see the documentation on corSymmNat and corBandNat, respectively).

USAGE:

asNatural(object, unconstrained) 

REQUIRED ARGUMENTS:

object
an object inheriting from class corStruct, representing a correlation 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 (except for corSymm and corBand objects), else, if unconstrained = FALSE , a corStruct object parameterized according to the constrained coefficients corresponding to object (except for corSymm and corBand objects) - the class corresponding to these objects is obtained by appending the name Nat to the end of the original class of object.

SEE ALSO:

, , ,

EXAMPLES:

cst1 <- corCompSymm(0.5, form = ~1|Subject) 
cst1 <- initialize(cst1, data = Orthodont) 
asNatural(cst1, unc = F)