library(lme4)
data(Oxboys, package = "nlme")
m3 <- pdLogChol(~ age)
m3
as(m3, 'pdmatrix') <- crossprod(model.matrix(formula(m3), Oxboys))
show(m3)
EMupdate(m3, length(levels(Oxboys$Subject))) <- diag(2)
show(m3)
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