◆ W_r

template<typename ThetaVec , typename WR , typename L_t , typename A_vec , typename ThetaGrad , typename LU_t , typename KRoot >

WR stan::math::internal::laplace_density_estimates< ThetaVec, WR, L_t, A_vec, ThetaGrad, LU_t, KRoot >::W_r

Solver-dependent Hessian quantity.

solver 1: sparse square root W_r = sqrt(W) where W = -d^2/dtheta^2 log_likelihood(theta) (diagonal or block-diagonal).
solvers 2/3: sparse W itself.