bertini::records::DrawStream Class Reference

A deterministic, fully-specified random stream (SHA-256 counter mode). More...

#include <derive.hpp>

Public Member Functions
	DrawStream ()=default
	Construct unseeded; the first draw self-seeds from entropy (unseeded runs stay random).
void	Reseed (std::uint64_t master, std::uint64_t domain, std::uint64_t index)
	Rekey the stream from (master seed, domain tag, stream index) under b2rand/1 and restart its counter.
std::uint64_t	Uint64 ()
	The next 8 stream bytes as a big-endian unsigned 64-bit integer.
double	UnitDouble ()
	Uniform on [0,1), exactly 53 bits: (Uint64 >> 11) * 2^-53.
double	SymmetricDouble ()
	Uniform on [-1,1]: 2*UnitDouble() - 1 (both operations exact).
mpz_int	Bits (unsigned num_bits)
	The next n bits as a nonnegative integer (big-endian bytes, masked).
mpz_int	IntSymmetric (mpz_int const &bound)
	Uniform integer on [-bound, bound], by rejection over Bits(bitlen(2*bound)).
real_mp	UnitRealMp (unsigned digits)
	Uniform on [0,1) at digits decimal digits: ldexp(Bits(k), -k) with k = ceil(digits*log2(10)) + 1, materialized at digits digits of precision.

Detailed Description

A deterministic, fully-specified random stream (SHA-256 counter mode).

One per thread in practice (see ThreadDrawStream); reseeded by the same (master, domain, index) tuples the legacy engine seeding uses, so setup / per-path / worker domain separation is preserved.

Constructor & Destructor Documentation

DrawStream()

bertini::records::DrawStream::DrawStream ( )

default

Construct unseeded; the first draw self-seeds from entropy (unseeded runs stay random).

Seeded runs call Reseed before any draw.

Member Function Documentation

Bits()

mpz_int bertini::records::DrawStream::Bits

(

unsigned

num_bits

)

The next n bits as a nonnegative integer (big-endian bytes, masked).

IntSymmetric()

mpz_int bertini::records::DrawStream::IntSymmetric

(

mpz_int const &

bound

)

Uniform integer on [-bound, bound], by rejection over Bits(bitlen(2*bound)).

Reseed()

void bertini::records::DrawStream::Reseed	(	std::uint64_t	master,
		std::uint64_t	domain,
		std::uint64_t	index )

Rekey the stream from (master seed, domain tag, stream index) under b2rand/1 and restart its counter.

SymmetricDouble()

double bertini::records::DrawStream::SymmetricDouble

(

)

Uniform on [-1,1]: 2*UnitDouble() - 1 (both operations exact).

Uint64()

std::uint64_t bertini::records::DrawStream::Uint64

(

)

The next 8 stream bytes as a big-endian unsigned 64-bit integer.

UnitDouble()

double bertini::records::DrawStream::UnitDouble

(

)

Uniform on [0,1), exactly 53 bits: (Uint64 >> 11) * 2^-53.

UnitRealMp()

real_mp bertini::records::DrawStream::UnitRealMp

(

unsigned

digits

)

Uniform on [0,1) at digits decimal digits: ldexp(Bits(k), -k) with k = ceil(digits*log2(10)) + 1, materialized at digits digits of precision.