diff options
Diffstat (limited to 'absl/random/beta_distribution.h')
-rw-r--r-- | absl/random/beta_distribution.h | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/absl/random/beta_distribution.h b/absl/random/beta_distribution.h index e29894f2037f..b09b02f0dde5 100644 --- a/absl/random/beta_distribution.h +++ b/absl/random/beta_distribution.h @@ -22,9 +22,10 @@ #include <ostream> #include <type_traits> -#include "absl/random/internal/distribution_impl.h" +#include "absl/meta/type_traits.h" #include "absl/random/internal/fast_uniform_bits.h" #include "absl/random/internal/fastmath.h" +#include "absl/random/internal/generate_real.h" #include "absl/random/internal/iostream_state_saver.h" namespace absl { @@ -275,15 +276,21 @@ typename beta_distribution<RealType>::result_type beta_distribution<RealType>::AlgorithmJoehnk( URBG& g, // NOLINT(runtime/references) const param_type& p) { + using random_internal::GeneratePositiveTag; + using random_internal::GenerateRealFromBits; + using real_type = + absl::conditional_t<std::is_same<RealType, float>::value, float, double>; + // Based on Joehnk, M. D. Erzeugung von betaverteilten und gammaverteilten // Zufallszahlen. Metrika 8.1 (1964): 5-15. // This method is described in Knuth, Vol 2 (Third Edition), pp 134. - using RandU64ToReal = typename random_internal::RandU64ToReal<result_type>; - using random_internal::PositiveValueT; + result_type u, v, x, y, z; for (;;) { - u = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g)); - v = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g)); + u = GenerateRealFromBits<real_type, GeneratePositiveTag, false>( + fast_u64_(g)); + v = GenerateRealFromBits<real_type, GeneratePositiveTag, false>( + fast_u64_(g)); // Direct method. std::pow is slow for float, so rely on the optimizer to // remove the std::pow() path for that case. @@ -327,12 +334,14 @@ typename beta_distribution<RealType>::result_type beta_distribution<RealType>::AlgorithmCheng( URBG& g, // NOLINT(runtime/references) const param_type& p) { + using random_internal::GeneratePositiveTag; + using random_internal::GenerateRealFromBits; + using real_type = + absl::conditional_t<std::is_same<RealType, float>::value, float, double>; + // Based on Cheng, Russell CH. Generating beta variates with nonintegral // shape parameters. Communications of the ACM 21.4 (1978): 317-322. // (https://dl.acm.org/citation.cfm?id=359482). - using RandU64ToReal = typename random_internal::RandU64ToReal<result_type>; - using random_internal::PositiveValueT; - static constexpr result_type kLogFour = result_type(1.3862943611198906188344642429163531361); // log(4) static constexpr result_type kS = @@ -341,8 +350,10 @@ beta_distribution<RealType>::AlgorithmCheng( const bool use_algorithm_ba = (p.method_ == param_type::CHENG_BA); result_type u1, u2, v, w, z, r, s, t, bw_inv, lhs; for (;;) { - u1 = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g)); - u2 = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g)); + u1 = GenerateRealFromBits<real_type, GeneratePositiveTag, false>( + fast_u64_(g)); + u2 = GenerateRealFromBits<real_type, GeneratePositiveTag, false>( + fast_u64_(g)); v = p.y_ * std::log(u1 / (1 - u1)); w = p.a_ * std::exp(v); bw_inv = result_type(1) / (p.b_ + w); |