Random Number Engines

Random number engines use seed data as an entropy source to generate pseudo-random numbers. oneDPL provides several class templates for customized engines, they are defined in the header <oneapi/dpl/random>.

Predefined Random Number Engines

Predefined random number engines are instantiations of random number engines class templates. The types below are defined in the header <oneapi/dpl/random> under the oneapi::dpl:: namespace.

The engines described below can efficiently generate vectors of random numbers. These types are defined in the header <oneapi/dpl/random> under the oneapi::dpl:: namespace.

Random Number Distributions

Random number distributions process the output of random number engines in such a way that the resulting output is distributed according to a defined statistical probability density function. They are defined in the header <oneapi/dpl/random> under the oneapi::dpl:: namespace.

Usage Model of oneDPL Random Number Generation Functionality

Random number generation is available for SYCL* device-side and host-side code. For example:

#include <iostream>
#include <vector>
#include <sycl/sycl.hpp>
#include <oneapi/dpl/random>

int main() {
    sycl::queue queue(sycl::default_selector_v);

    std::int64_t nsamples = 100;
    std::uint32_t seed = 777;
    std::vector<float> x(nsamples);
    {
        sycl::buffer<float, 1> x_buf(x.data(), sycl::range<1>(x.size()));

        queue.submit([&] (sycl::handler &cgh) {

            auto x_acc =
            x_buf.template get_access<sycl::access::mode::write>(cgh);

            cgh.parallel_for<class count_kernel>(sycl::range<1>(nsamples),
                [=](sycl::item<1> idx) {
                std::uint64_t offset = idx.get_linear_id();

                // Create minstd_rand engine
                oneapi::dpl::minstd_rand engine(seed, offset);

                // Create float uniform_real_distribution distribution
                oneapi::dpl::uniform_real_distribution<float> distr;

                // Generate float random number
                auto res = distr(engine);

                // Store results to x_acc
                x_acc[idx] = res;
            });
        });
    }

    std::cout << "\nFirst 5 samples of minstd_rand with scalar generation" << std::endl;
    for(int i = 0; i < 5; i++) {
        std::cout << x.begin()[i] << std::endl;
    }

    std::cout << "\nLast 5 samples of minstd_rand with scalar generation" << std::endl;
    for(int i = 0; i < 5; i++) {
        std::cout << x.rbegin()[i] << std::endl;
    }
    return 0;
}