API Reference

All names below are exported by the RandomDataStreams module unless marked (internal).

Types

AbstractRNGStream — supertype of stream generators (objects that mint new independent streams): MRG32k3aGen, Xoshiro256plusGen.

AbstractStreamableRNG <: Random.AbstractRNG — supertype of usable RNGs that can navigate streams and substreams: MRG32k3a, Xoshiro256p.

MRG32k3a

Constructors

Seeds are validated with checkseed; invalid seeds throw an AssertionError.

Functions

rand(rng::MRG32k3a) -> Float64 Uniform in [0, 1) with ~32 bits of resolution. This is the native output.

rand(rng::MRG32k3a, T) Supported T: Float64, Float32, Float16, UInt8…UInt128, Int8…Int128, Bool, and any UnitRange (e.g. rand(rng, 1:10)).

reset_stream!(rng) -> rng Set the current state (Cg) and the substream start (Bg) back to the stream start (Ig).

reset_substream!(rng) -> rng Set Cg back to Bg.

next_substream!(rng) -> rng Advance Bg to the next substream boundary (jump of ≈ 2^76 steps) and set Cg = Bg.

advance_state!(rng, e::Integer, c::Integer) Jump forward/backward inside the current substream by n steps where n = 2^e + c. Negative e or c move backwards. Cost is O(max(|e|, log |c|)) matrix operations.

get_state(rng) -> Vector{Int} Return a copy of Cg.

checkseed(x) -> Bool true iff x has length 6, all entries ≥ 0, entries 1–3 are < m1 and not all zero, entries 4–6 are < m2 and not all zero.

DEFAULT_SEED The constant seed vector used by MRG32k3a() and MRG32k3aGen().

copy(m::MRG32k3a) -> MRG32k3a Independent deep copy of the generator (all three state vectors).

Stream generation

Xoshiro256+

Constructors

Functions

rand(rng::Xoshiro256p) -> Float64 Uniform in [0, 1), built from a full 64-bit draw.

rand(rng::Xoshiro256p, T) Supported T: Float64, Float32, Float16, UInt64, and UnitRange{Int64} (uniform, unbiased modulo sampling).

srand!(rng, seed::Vector{UInt64}) -> rng Re-seed an existing generator (first 4 words are used).

reset_stream!(rng) -> rng, reset_substream!(rng) -> rng, next_substream!(rng) -> rng Same semantics as for MRG32k3a; next_substream! performs a short_jump! (leap of ≈ 2^96 values).

short_jump!(rng) -> rng Jump to the beginning of the next 2^96-value block (Vigna's short jump).

long_jump!(rng) -> rng Leap ≈ 2^192 values ahead — used to delimit streams.

get_state(rng) -> Vector{UInt64} Copy of the current state Cg.

copy(rng) -> Xoshiro256p Independent copy.

(internal) next(rng) -> UInt64: raw 64-bit output; also available as rand(rng, UInt64).

Stream generation

Xoshiro / xoroshiro families

All variants share one implementation (LinRNG{N,S} internally, N = state words, S = scrambler) and expose the same API as Xoshiro256+ above. Exported types:

Constructors accept an NTuple{N,UInt64} or a Vector{<:Unsigned} of length N (1 or 3 arguments). Available functions: rand (Float64/Float32/Float16, UInt64, ranges), srand!, reset_stream!, reset_substream!, next_substream!, short_jump!, long_jump!, get_state, copy.

advance_state!(rng, e::Integer, c::Integer) -> rng Jump forward by n steps (n = 2^e + c if e > 0, n = -2^(-e) + c if e < 0, n = c if e = 0) or backward if n < 0. Implemented by computing the jump polynomial x^n mod p(x) over GF(2) (p = the family's characteristic polynomial) and applying it to the current state; distances are reduced modulo the period. Only Cg moves — stream/substream boundaries are kept. Cost is O((64N)²) GF(2) operations (≈ 10–500 ms depending on family); for the standard distances prefer short_jump!/long_jump!, which use precomputed constants and are allocation-free.

Jump semantics (all xoshiro-family generators):

• short_jump!(rng) — jump anchored at the current substream start (Bg); lands at the next substream boundary (2^64 values for xoroshiro128, 2^128 for xoshiro256, 2^256 for xoshiro512).
• long_jump!(rng) — jump anchored at the stream start (Ig); delimits independent streams.
• next_stream!(gen) applies the long-jump polynomial to the stored seed.

All jump constants are the official ones from xoshiro.di.unimi.it and outputs are validated byte-for-byte against the original C implementations.

Method index