Count Engine Adaptor

count_engine_adaptor is a random number engine adaptor that counts how many times random 32 bits were taken from the engine during the generate call.

Description

This adaptor helps to query how many random numbers were taken from an engine during the generate call. Especially it’s useful for distributions based on the acceptance-rejection algorithms, e.g. beta, gamma.

class count_engine_adaptor

Syntax

 namespace oneapi::math::rng::device {
  template <typename Engine>
  class count_engine_adaptor {
  public:
      static constexpr std::int32_t vec_size = Engine::vec_size;

      // ctors
      explicit count_engine_adaptor(const Engine& engine);
      explicit count_engine_adaptor(Engine&& engine);

      template <typename... Params>
      count_engine_adaptor(Params... params);

      // getters
      std::int64_t get_count() const;
      const Engine& base() const;
  };
}

Class Template Parameters

Engine

Describes the type of the engine that count_engine_adaptor is constructed over.

Class Members

Routine	Description
explicit count_engine_adaptor(const Engine& engine)	Constructs the adaptor over engine.
explicit count_engine_adaptor(Engine&& engine)	Constructs the adaptor over engine by moving.
count_engine_adaptor(Params... params)	Constructs the adaptor generating an engine inside. params is a pack of input parameters to create an engine.
std::int64_t get_count() const	This method returns the amount of random numbers generated by generate.
const Engine& base() const	Returns the underlying engine.

Example

namespace rng_device = oneapi::math::rng::device;

sycl::event my_event = q.parallel_for({n}, [=](std::size_t idx) {
    // Some code...

    rng_device::count_engine_adaptor<rng_device::mcg59<VecSize>> adaptor(seed, idx);
    r[idx] = rng_device::generate(distr, adaptor);

    consumed[idx] = adaptor.get_count();

    // continue work with engine if needed
    auto engine = adaptor.base();
    // ...
});

Parent topic: Engine Adaptors