uniform (Discrete)

oneMKL - Data Parallel C++ Developer Reference

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ID 772045

Date 10/15/2026

Version

Public

uniform (Discrete)

Generates random numbers uniformly distributed over the interval [a, b).

Description
API

Description

The uniform class object is used in generate functions to provide random numbers uniformly distributed over the interval [a, b), where a, b are the left and right bounds of the interval respectively, and \(a, b \in Z ; a < b\).

The probability distribution is given by:

\[P(X = k) = \frac{1}{b-a}, k \in \{a, a + 1, \ldots, b-1\}\]

The cumulative distribution function is as follows:

\[\begin{split}F_{a, b}(x) = \begin{cases} 0, & x < a \\ \frac{x-a + 1}{b-a}, & a \leq x < b \\ 1, & x \geq b \end{cases}, x \in R\end{split}\]

API

Syntax

namespace oneapi::mkl::rng::device {
  template<typename Type, typename Method>
  class uniform {
  public:
    using method_type = Method;
    using result_type = Type;

    uniform(): uniform((Type)0,
                 std::is_integral<Type>::value
                  ? ((std::is_same_v<Method, uniform_method::standard> && sizeof(Type) == 32)
                       ? (1 << 23)
                       : std::numeric_limits<Type>::max())
                  : (Type)1) {};
    explicit uniform(Type a, Type b);
    explicit uniform(const param_type& pt);

    Type a() const;
    Type b() const;
    param_type param() const;
    void param(const param_type& pt);
  };
}

Include Files

oneapi/mkl/rng/device.hpp

Template Parameters

typename Method

Generation method. The specific values are as follows:

oneapi::mkl::rng::device::uniform_method::standard

oneapi::mkl::rng::device::uniform_method::accurate

See brief descriptions of the methods in Distributions Template Parameter Method.

NOTE:

The oneapi::mkl::rng::device::uniform_method::standard uses the float type for underlying BRNG calls. This might cause the produced numbers to have incorrect statistics (due to rounding error) when \((abs(b – a) > 2^{23} || abs(b) > 2^{23} || abs(a) > 2^{23})\). To get proper statistics for this case, use the oneapi::mkl::rng::device::uniform_method::accurate method instead.

NOTE:

For (u)int8 and (u)int16 small types, the numbers are always generated as single-precision floating-point numbers.

Input Parameters

Name	Type	Description
a	`std::int8_t` `std::uint8_t` `std::int16_t` `std::uint16_t` `std::int32_t` `std::uint32_t` `std::int64_t` `std::uint64_t`	Left bound `a`
b	`std::int8_t` `std::uint8_t` `std::int16_t` `std::uint16_t` `std::int32_t` `std::uint32_t` `std::int64_t` `std::uint64_t`	Right bound `b`

Name

Type

Description

std::int8_t

std::uint8_t

std::int16_t

std::uint16_t

std::int32_t

std::uint32_t

std::int64_t

std::uint64_t

Left bound a

std::int8_t

std::uint8_t

std::int16_t

std::uint16_t

std::int32_t

std::uint32_t

std::int64_t

std::uint64_t

Right bound b

NOTE:

The sample rejection method is used in the case of the 64-bit return type. This enables sequences to not overlap in the case of parallel generation. To ensure the output quality, provide an ample offset between engines.

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oneMKL - Data Parallel C++ Developer Reference

uniform (Discrete)

Description

API