binomial_rng.hpp

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#ifndef STAN_MATH_PRIM_PROB_BINOMIAL_RNG_HPP
#define STAN_MATH_PRIM_PROB_BINOMIAL_RNG_HPP
 
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/err.hpp>
#include <stan/math/prim/fun/max_size.hpp>
#include <stan/math/prim/fun/size_zero.hpp>
#include <stan/math/prim/fun/scalar_seq_view.hpp>
#include <boost/random/binomial_distribution.hpp>
#include <boost/random/variate_generator.hpp>
 
namespace stan {
namespace math {
 
template <typename T_N, typename T_theta, class RNG>
inline typename VectorBuilder<true, int, T_N, T_theta>::type binomial_rng(
    const T_N& N, const T_theta& theta, RNG& rng) {
  using boost::binomial_distribution;
  using boost::variate_generator;
  using T_N_ref = ref_type_t<T_N>;
  using T_theta_ref = ref_type_t<T_theta>;
  static constexpr const char* function = "binomial_rng";
  check_consistent_sizes(function, "Population size parameter", N,
                         "Probability Parameter", theta);
  if (size_zero(N, theta)) {
    return {};
  }
 
  T_N_ref N_ref = N;
  T_theta_ref theta_ref = theta;
  check_nonnegative(function, "Population size parameter", N_ref);
  check_bounded(function, "Probability parameter", value_of(theta_ref), 0.0,
                1.0);
 
  scalar_seq_view<T_N_ref> N_vec(N_ref);
  scalar_seq_view<T_theta_ref> theta_vec(theta_ref);
  size_t M = max_size(N, theta);
  VectorBuilder<true, int, T_N, T_theta> output(M);
 
  for (size_t m = 0; m < M; ++m) {
    variate_generator<RNG&, binomial_distribution<> > binomial_rng(
        rng, binomial_distribution<>(N_vec[m], theta_vec[m]));
 
    output[m] = binomial_rng();
  }
 
  return output.data();
}
 
}  // namespace math
}  // namespace stan
#endif