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)