Extract Square-Root Factor from Components of an reStruct Object

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

# 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.

References

Pinheiro, J.C., and Bates, D.M. (2000) "Mixed-Effects Models in S and S-PLUS", Springer.

Author

José Pinheiro and Douglas Bates bates@stat.wisc.edu

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.

Examples

rs1 <- reStruct(pdSymm(diag(3), ~age+Sex, data = Orthodont))
pdFactor(rs1)
#> [1] 1 0 0 0 1 0 0 0 1