pdFactor.reStruct {nlme}R Documentation

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

## S3 method for class 'reStruct':
pdFactor(object)

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.

Author(s)

Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu

See Also

pdMatrix.reStruct, pdFactor.pdMat

Examples

data(Orthodont)
rs1 <- reStruct(pdSymm(diag(3), ~age+Sex, data = Orthodont))
pdFactor(rs1)
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