beta_binomial_rng.hpp

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#ifndef STAN_MATH_PRIM_PROB_BETA_BINOMIAL_RNG_HPP
#define STAN_MATH_PRIM_PROB_BETA_BINOMIAL_RNG_HPP
 
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/prob/binomial_rng.hpp>
#include <stan/math/prim/prob/beta_rng.hpp>
#include <stan/math/prim/fun/size_zero.hpp>
 
namespace stan {
namespace math {
 
template <typename T_N, typename T_shape1, typename T_shape2, class RNG>
inline typename VectorBuilder<true, int, T_N, T_shape1, T_shape2>::type
beta_binomial_rng(const T_N &N, const T_shape1 &alpha, const T_shape2 &beta,
                  RNG &rng) {
  using T_N_ref = ref_type_t<T_N>;
  using T_alpha_ref = ref_type_t<T_shape1>;
  using T_beta_ref = ref_type_t<T_shape2>;
  static constexpr const char *function = "beta_binomial_rng";
  check_consistent_sizes(function, "First prior sample size parameter", alpha,
                         "Second prior sample size parameter", beta);
 
  if (size_zero(N, alpha, beta)) {
    return {};
  }
 
  T_N_ref N_ref = N;
  T_alpha_ref alpha_ref = alpha;
  T_beta_ref beta_ref = beta;
  check_nonnegative(function, "Population size parameter", N_ref);
  check_positive_finite(function, "First prior sample size parameter",
                        alpha_ref);
  check_positive_finite(function, "Second prior sample size parameter",
                        beta_ref);
 
  auto p = beta_rng(alpha_ref, beta_ref, rng);
  return binomial_rng(N_ref, p, rng);
}
 
}  // namespace math
}  // namespace stan
#endif