Struct xorshift::xoroshiro128::Xoroshiro128

pub struct Xoroshiro128(_);

A random number generator that uses the xoroshiro128+ algorithm [1].

Description

Quoted from [1].

This is the successor to xorshift128+. It is the fastest full-period generator passing BigCrush without systematic failures, but due to the relatively short period it is acceptable only for applications with a mild amount of parallelism; otherwise, use a xorshift1024* generator.

Beside passing BigCrush, this generator passes the PractRand test suite up to (and included) 16TB, with the exception of binary rank tests, which fail due to the lowest bit being an LFSR; all other bits pass all tests. We suggest to use a sign test to extract a random Boolean value.

Note that the generator uses a simulated rotate operation, which most C compilers will turn into a single instruction. In Java, you can use Long.rotateLeft(). In languages that do not make low-level rotation instructions accessible xorshift128+ could be faster.

The state must be seeded so that it is not everywhere zero. If you have a 64-bit seed, we suggest to seed a splitmix64 generator and use its output to fill s.

[1]: Sebastiano Vigna, and David Blackman xoroshiro128+

Parallelism

The RngJump implementation is equivalent to 2⁶⁴ calls to next_u64(). Used to generate 2⁶⁴ non-overlapping subsequences for parallel computations.

Trait Implementations

impl Copy for Xoroshiro128

impl Clone for Xoroshiro128

fn clone(&self) -> Xoroshiro128

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Rng for Xoroshiro128

fn next_u32(&mut self) -> u32

Return the next random u32.

fn next_u64(&mut self) -> u64

Return the next random u64.

fn next_f32(&mut self) -> f32

Return the next random f32 selected from the half-open interval [0, 1).

fn next_f64(&mut self) -> f64

Return the next random f64 selected from the half-open interval [0, 1).

fn fill_bytes(&mut self, dest: &mut [u8])

Fill dest with random data.

fn gen<T>(&mut self) -> T where
    T: Rand, 

Return a random value of a Rand type.

fn gen_iter<T>(&'a mut self) -> Generator<'a, T, Self> where
    T: Rand, 

Return an iterator that will yield an infinite number of randomly generated items.

fn gen_range<T>(&mut self, low: T, high: T) -> T where
    T: SampleRange + PartialOrd<T>, 

Generate a random value in the range [low, high).

fn gen_weighted_bool(&mut self, n: u32) -> bool

Return a bool with a 1 in n chance of true

fn gen_ascii_chars(&'a mut self) -> AsciiGenerator<'a, Self>

Return an iterator of random characters from the set A-Z,a-z,0-9.

fn choose<T>(&mut self, values: &'a [T]) -> Option<&'a T>

Return a random element from values.

fn choose_mut<T>(&mut self, values: &'a mut [T]) -> Option<&'a mut T>

Return a mutable pointer to a random element from values.

fn shuffle<T>(&mut self, values: &mut [T])

Shuffle a mutable slice in place.

impl<'a> SeedableRng<&'a [u64]> for Xoroshiro128

fn reseed(&mut self, seed: &'a [u64])

Reseed an RNG with the given seed.

fn from_seed(seed: &'a [u64]) -> Xoroshiro128

Create a new RNG with the given seed.

impl Rand for Xoroshiro128

fn rand<R: Rng>(other: &mut R) -> Xoroshiro128

Generates a random instance of this type using the specified source of randomness.

impl RngJump for Xoroshiro128

fn jump(&mut self, count: usize)

Forward the state of the random number generator.