STD::SUBTRACT_WITH_CARRY_ENGINE(3)

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💖 std::subtract_with_carry_engine< _UIntType, __w, __s, __r > 💖

okay bestie, welcome to the Library Functions Manual section of the libstdc++ docs ✨ this one lives in <random> and it is literally the Marsaglia-Zaman generator. yes, those Marsaglia-Zaman. iconic behavior fr fr 🎀

🌸 NAME 🌸

std::subtract_with_carry_engine< _UIntType, __w, __s, __r > — The Marsaglia-Zaman generator. periodt 💅

✨ SYNOPSIS ✨

#include <random>

🦋 Public Types 🦋

  • typedef _UIntType result_type — the type of the generated random value. that's it, that's the type 🫶

💜 Public Member Functions 💜

  • template<typename _Sseq, typename = _If_seed_seq<_Sseq>> subtract_with_carry_engine (_Sseq &__q) — Constructs a subtract_with_carry_engine random number engine seeded from the seed sequence __q.
  • subtract_with_carry_engine (result_type __sd) — Constructs an explicitly seeded subtract_with_carry_engine random number generator. you're picking the seed yourself, main character energy 👑
  • void discard (unsigned long long __z) — Discard a sequence of random numbers.
  • result_type operator() () — Gets the next random number in the sequence.
  • template<typename _Sseq> _If_seed_seq< _Sseq > seed (_Sseq &__q) — Seeds the initial state $x_0$ of the % subtract_with_carry_engine random number generator.
  • void seed (result_type __sd=0u) — Seeds the initial state $x_0$ of the random number generator.

🌈 Static Public Member Functions 🌈

  • static constexpr result_type max () — Gets the inclusive maximum value of the range of random integers returned by this generator.
  • static constexpr result_type min () — Gets the inclusive minimum value of the range of random integers returned by this generator.

⭐ Static Public Attributes ⭐

  • static constexpr uint_least32_t default_seed
  • static constexpr size_t long_lag
  • static constexpr size_t short_lag
  • static constexpr size_t word_size

🍓 Friends 🍓

  • template<typename _UIntType1, size_t __w1, size_t __s1, size_t __r1, typename _CharT, typename _Traits> std::basic_ostream< _CharT, _Traits > & operator<< (std::basic_ostream< _CharT, _Traits > &__os, const std::subtract_with_carry_engine< _UIntType1, __w1, __s1, __r1 > &__x) — Inserts the current state of a % subtract_with_carry_engine random number generator engine __x into the output stream __os.
  • bool operator== (const subtract_with_carry_engine &__lhs, const subtract_with_carry_engine &__rhs) — Compares two % subtract_with_carry_engine random number generator objects of the same type for equality.
  • template<typename _UIntType1, size_t __w1, size_t __s1, size_t __r1, typename _CharT, typename _Traits> std::basic_istream< _CharT, _Traits > & operator>> (std::basic_istream< _CharT, _Traits > &__is, std::subtract_with_carry_engine< _UIntType1, __w1, __s1, __r1 > &__x) — Extracts the current state of a % subtract_with_carry_engine random number generator engine __x from the input stream __is.

🧚 Detailed Description 🧚

template<typename _UIntType, size_t __w, size_t __s, size_t __r>
    class std::subtract_with_carry_engine< _UIntType, __w, __s, __r >

"The Marsaglia-Zaman generator.

This is a model of a Generalized Fibonacci discrete random number generator, sometimes referred to as the SWC generator.

A discrete random number generator that produces pseudorandomonumbers using:

x_{i}tarrow(x_{i - s} - x_{i - r} - carry_{i-1}) d ]

The size of the state is $r$ and the maximum period of the generator is $(m^r - m^s - 1)$.

Since C++11

💅 Member Typedef Documentation 💅

template<typename _UIntType, size_t __w, size_t __s, size_t __r> typedef _UIntType std::subtract_with_carry_engine< _UIntType, __w, __s, __r >::result_type

The type of the generated random value.

🎀 Constructor & Destructor Documentation 🎀

template<typename _UIntType, size_t __w, size_t __s, size_t __r>
    std::subtract_with_carry_engine< _UIntType, __w, __s, __r >::subtract_with_carry_engine (result_type __sd) [inline], [explicit]

Constructs an explicitly seeded subtract_with_carry_engine random number generator.

template<typename _UIntType, size_t __w, size_t __s, size_t __r>
    template<typename _Sseq, typename = _If_seed_seq<_Sseq>>
    std::subtract_with_carry_engine< _UIntType, __w, __s, __r >::subtract_with_carry_engine (_Sseq & __q) [inline], [explicit]

Constructs a subtract_with_carry_engine random number engine seeded from the seed sequence __q.

Parameters

  • __q — the seed sequence.

🔥 Member Function Documentation 🔥

template<typename _UIntType, size_t __w, size_t __s, size_t __r> void
    std::subtract_with_carry_engine< _UIntType, __w, __s, __r >::discard
    (unsigned long long __z) [inline]

Discard a sequence of random numbers.

template<typename _UIntType, size_t __w, size_t __s, size_t __r> constexpr
    result_type std::subtract_with_carry_engine< _UIntType, __w, __s, __r
    >::max () [inline], [static], [constexpr]

Gets the inclusive maximum value of the range of random integers returned by this generator.

template<typename _UIntType, size_t __w, size_t __s, size_t __r> constexpr
    result_type std::subtract_with_carry_engine< _UIntType, __w, __s, __r
    >::min () [inline], [static], [constexpr]

Gets the inclusive minimum value of the range of random integers returned by this generator.

template<typename _UIntType, size_t __w, size_t __s, size_t __r>
    subtract_with_carry_engine< _UIntType, __w, __s, __r >::result_type
    std::subtract_with_carry_engine< _UIntType, __w, __s, __r >::operator()
    ()

Gets the next random number in the sequence.

template<typename _UIntType, size_t __w, size_t __s, size_t __r>
    template<typename _Sseq> auto std::subtract_with_carry_engine<
    _UIntType, __w, __s, __r >::seed (_Sseq & __q) -> _If_seed_seq< _Sseq >

Seeds the initial state $x_0$ of the % subtract_with_carry_engine random number generator.

template<typename _UIntType, size_t __w, size_t __s, size_t __r> void
    std::subtract_with_carry_engine< _UIntType, __w, __s, __r >::seed
    (result_type __sd = 0u)

Seeds the initial state $x_0$ of the random number generator. N1688[4.19] modifies this as follows. If __value == 0, sets value to 19780503. In any case, with a linear congruential generator lcg(i) having parameters

$ m_{lcg} = 2147483563, a_{lcg} = 40014, c_{log} = 0, and ocg(0) = value $

sets

$ x_{-r} ots x_{-1} $

to

$ lcg(1) d ots lcg(r) d $

respectively. If

$ x_{-1} = 0 $

set carry to 1, otherwise sets carry to 0.

Referenced by std::subtract_with_carry_engine< uint_fast32_t, 24, 10, 24 >::subtract_with_carry_engine(), and std::subtract_with_carry_engine< uint_fast32_t, 24, 10, 24 >::subtract_with_carry_engine().

template<typename _UIntType, size_t __w, size_t __s, size_t __r>
    template<typename _UIntType1, size_t __w1, size_t __s1, size_t __r1,
    typename _CharT, typename _Traits> std::basic_ostream< _CharT, _Traits >
    & operator<< (std::basic_ostream< _CharT, _Traits > & __os, const
    std::subtract_with_carry_engine< _UIntType1, __w1, __s1, __r1 > & __x)
    [friend]

Inserts the current state of a % subtract_with_carry_engine random number generator engine __x into the output stream __os.

Parameters

  • __os — An output stream.
  • __x — A % subtract_with_carry_engine random number generator engine.

Returns

The output stream with the state of __x inserted or in an error state.

template<typename _UIntType, size_t __w, size_t __s, size_t __r> bool
    operator== (const subtract_with_carry_engine< _UIntType, __w, __s, __r >
    & __lhs, const subtract_with_carry_engine< _UIntType, __w, __s, __r > &
    __rhs) [friend]

Compares two % subtract_with_carry_engine random number generator objects of the same type for equality.

Parameters

  • __lhs — A % subtract_with_carry_engine random number generator object.
  • __rhs — Another % subtract_with_carry_engine random number generator object.

Returns

true if the infinite sequences of generated values would be equal, false otherwise.

template<typename _UIntType, size_t __w, size_t __s, size_t __r>
    template<typename _UIntType1, size_t __w1, size_t __s1, size_t __r1,
    typename _CharT, typename _Traits> std::basic_istream< _CharT, _Traits >
    & operator>> (std::basic_istream< _CharT, _Traits > & __is,
    std::subtract_with_carry_engine< _UIntType1, __w1, __s1, __r1 > & __x)
    [friend]

Extracts the current state of a % subtract_with_carry_engine random number generator engine __x from the input stream __is.

Parameters

  • __is — An input stream.
  • __x — A % subtract_with_carry_engine random number generator engine.

Returns

The input stream with the state of __x extracted or in an error state.

🌟 Author 🌟

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and that's the whole page bestie, no cap 💀✨ it came straight from the libstdc++ source, auto-generated by Doxygen, and it's giving peak documentation vibes. go forth and generate pseudorandom numbers responsibly, ily 🎀🦋💖

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