Extract Square-Root Factor from Components of an reStruct Object
DESCRIPTION:
This method function extracts square-root factors of the
positive-definite matrices corresponding to the
pdMat elements
of
object.
USAGE:
pdFactor(object)
REQUIRED ARGUMENTS:
object
an object inheriting from class
reStruct,
representing a random effects structure and consisting of a list of
pdMat objects.
VALUE:
a vector with square-root factors of the positive-definite matrices
corresponding to the elements of
object stacked column-wise.
NOTE: This function is used intensively in optimization
algorithms and its value is returned as a vector for efficiency
reasons. The
pdMatrix function can be used to obtain
square-root factors in matrix form.
SEE ALSO:
,
EXAMPLES:
rs1 <- reStruct(pdSymm(diag(3), form = ~age + Sex, data = Orthodont))
pdFactor(rs1)