Maps one re_list element to the two representations the Laplace path needs:
pack, the value the C++ kernel consumes (a length-n_coefs marginal-SD
vector for a diagonal / uncorrelated term, or a packed lower-triangular
Cholesky of length n_coefs (n_coefs + 1) / 2 for a correlated one), and
Q, the n_coefs x n_coefs RE precision Sigma^{-1} used to build the
marginal fixed-effect SE. A correlated term is signalled by r$L (a lower-
triangular Cholesky factor, Sigma = L L') or r$cov (the covariance
matrix); when present these take precedence over r$sigma.
Arguments
- r
One element of a
re_list(seetulpa_laplace()).