> x <- matrix(1, nrow=3, ncol=3)
> Q <- chol(x, pivot=TRUE)
> oo <- order(attr(Q, 'pivot'))
> t(Q[, oo]) %*% Q[, oo]
     [,1] [,2] [,3]
[1,]    1    1    1
[2,]    1    1    1
[3,]    1    1    3