This function computes the Metropolis-Hastings ratio to decide whether to accept or reject a new value for logU.
logacceptance_ratio_logu(logu, logu_prime, n, r, gamma, kappa, a, delta)
Real, log of the latent variable U at the current iteration.
Real, log of the new proposed latent variable U.
Integer, number of data points.
Integer, number of clusters.
Positive real. A parameter of the NRMI process.
Positive real. Total mass of the centering measure.
Scale of the Metropolis-Hastings proposal distribution