Simulate prior distribution parameters for the GGUM model
d_thetas_prior(x, ...)
d_alpha_prior(x, ...)
d_delta_prior(x, ...)
d_tau_prior(x, ...)
r_thetas_prior(n, ...)
r_alpha_prior(n, ...)
r_delta_prior(n, ...)
r_tau_prior(n, ...)vector of quantiles
additional arguments to pass to the prior functions
number of observations required for the simulation