beta_binomial_lpmf.hpp

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#ifndef STAN_MATH_OPENCL_PRIM_BETA_BINOMIAL_LPMF_HPP
#define STAN_MATH_OPENCL_PRIM_BETA_BINOMIAL_LPMF_HPP
#ifdef STAN_OPENCL
 
#include <stan/math/opencl/kernel_generator.hpp>
#include <stan/math/opencl/prim/size.hpp>
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/err.hpp>
#include <stan/math/prim/fun/constants.hpp>
#include <stan/math/prim/fun/digamma.hpp>
#include <stan/math/prim/fun/lgamma.hpp>
#include <stan/math/prim/fun/max_size.hpp>
#include <stan/math/prim/functor/partials_propagator.hpp>
#include <stan/math/prim/fun/elt_multiply.hpp>
#include <stan/math/prim/fun/elt_divide.hpp>
 
namespace stan {
namespace math {
 
template <
    bool propto, typename T_n_cl, typename T_N_cl, typename T_size1_cl,
    typename T_size2_cl,
    require_all_prim_or_rev_kernel_expression_t<T_n_cl, T_size1_cl,
                                                T_size2_cl>* = nullptr,
    require_any_not_stan_scalar_t<T_n_cl, T_size1_cl, T_size2_cl>* = nullptr>
inline return_type_t<T_n_cl, T_size1_cl, T_size2_cl> beta_binomial_lpmf(
    const T_n_cl& n, const T_N_cl N, const T_size1_cl& alpha,
    const T_size2_cl& beta) {
  using std::isfinite;
  static constexpr const char* function = "beta_binomial_lpmf(OpenCL)";
 
  check_consistent_sizes(function, "Successes variable", n,
                         "Population size parameter", N,
                         "First prior sample size parameter", alpha,
                         "Second prior sample size parameter", beta);
  const size_t N_size = max_size(n, N, alpha, beta);
  if (N_size == 0) {
    return 0.0;
  }
  if constexpr (!include_summand<propto, T_size1_cl, T_size2_cl>::value) {
    return 0.0;
  }
 
  const auto& alpha_col = as_column_vector_or_scalar(alpha);
  const auto& beta_col = as_column_vector_or_scalar(beta);
 
  const auto& alpha_val = value_of(alpha_col);
  const auto& beta_val = value_of(beta_col);
 
  auto check_N_nonnegative
      = check_cl(function, "Population size parameter", N, "nonnegative");
  auto N_nonnegative = N >= 0;
  auto check_alpha_pos_finite
      = check_cl(function, "First prior sample size parameter", alpha_val,
                 "positive finite");
  auto alpha_pos_finite = alpha_val > 0.0 && isfinite(alpha_val);
  auto check_beta_pos_finite
      = check_cl(function, "First prior sample size parameter", beta_val,
                 "positive finite");
  auto beta_pos_finite = beta_val > 0.0 && isfinite(beta_val);
 
  auto return_neg_inf = (n < 0 || n > N) + constant(0, N_size, 1);
  auto lbeta_diff
      = lbeta(n + alpha_val, N - n + beta_val) - lbeta(alpha_val, beta_val);
  auto digamma_diff
      = digamma(alpha_val + beta_val) - digamma(N + alpha_val + beta_val);
  auto logp_expr = colwise_sum(static_select<include_summand<propto>::value>(
      binomial_coefficient_log(N, n) + lbeta_diff, lbeta_diff));
 
  auto alpha_deriv = digamma(n + alpha_val) + digamma_diff - digamma(alpha_val);
  auto beta_deriv
      = digamma(N - n + beta_val) + digamma_diff - digamma(beta_val);
 
  matrix_cl<double> logp_cl;
  matrix_cl<int> return_neg_inf_cl;
  matrix_cl<double> alpha_deriv_cl;
  matrix_cl<double> beta_deriv_cl;
 
  results(check_N_nonnegative, check_alpha_pos_finite, check_beta_pos_finite,
          logp_cl, alpha_deriv_cl, beta_deriv_cl)
      = expressions(N_nonnegative, alpha_pos_finite, beta_pos_finite, logp_expr,
                    calc_if<is_autodiff_v<T_size1_cl>>(alpha_deriv),
                    calc_if<is_autodiff_v<T_size2_cl>>(beta_deriv));
 
  if (from_matrix_cl(return_neg_inf_cl).any()) {
    return LOG_ZERO;
  }
 
  double logp = sum(from_matrix_cl(logp_cl));
 
  auto ops_partials = make_partials_propagator(alpha_col, beta_col);
  if constexpr (is_autodiff_v<T_size1_cl>) {
    partials<0>(ops_partials) = std::move(alpha_deriv_cl);
  }
  if constexpr (is_autodiff_v<T_size2_cl>) {
    partials<1>(ops_partials) = std::move(beta_deriv_cl);
  }
 
  return ops_partials.build(logp);
}
 
}  // namespace math
}  // namespace stan
#endif
#endif