inline float sample_beta (
rng_t & rng,
float alpha,
float beta)
{
float x = sample_gamma(rng, alpha);
float y = sample_gamma(rng, beta);
return x / (x + y);
}
void init(
const Shared & shared,
const Group & group,
rng_t & rng) {
Shared post = shared.plus_group(group);
mean = sample_gamma(rng, post.alpha, 1.f / post.inv_beta);
}
double LogNormalHyperPrior::init() {
boost::random::lognormal_distribution<> lognormal_dist(location, scale);
boost::random::variate_generator<boost::random::mt19937*, boost::random::lognormal_distribution<> > sample_gamma(mt_rng_pt, lognormal_dist);
double gamma = sample_gamma();
return gamma;
}
double GammaHyperPrior::init() {
boost::random::gamma_distribution<> gamma_dist(shape, scale);
boost::random::variate_generator<boost::random::mt19937*, boost::random::gamma_distribution<> > sample_gamma(mt_rng_pt, gamma_dist);
double gamma = sample_gamma();
return gamma;
}
