Extract Square-Root Factor from Components of an reStruct Object

Usage

pdFactor(object)

Arguments

object an object inheriting from class reStruct, representing a random effects structure and consisting of a list of pdMat objects.

Description

This method function extracts square-root factors of the positive-definite matrices corresponding to the pdMat elements of object.

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.

Author(s)

Jose Pinheiro and Douglas Bates

See Also

pdMatrix.reStruct, pdFactor.pdMat

Examples

library(lme)
rs1 <- reStruct(pdSymm(diag(3)))
pdFactor(rs1)

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