# Struct rand_pcg::Mcg128Xsl64

source · [−]`pub struct Mcg128Xsl64 { /* private fields */ }`

## Expand description

A PCG random number generator (XSL 128/64 (MCG) variant).

Permuted Congruential Generator with 128-bit state, internal Multiplicative Congruential Generator, and 64-bit output via “xorshift low (bits), random rotation” output function.

This is a 128-bit MCG with the PCG-XSL-RR output function, also known as
`pcg64_fast`

.
Note that compared to the standard `pcg64`

(128-bit LCG with PCG-XSL-RR
output function), this RNG is faster, also has a long cycle, and still has
good performance on statistical tests.

## Implementations

source### impl Mcg128Xsl64

### impl Mcg128Xsl64

source#### pub fn advance(&mut self, delta: u128)

#### pub fn advance(&mut self, delta: u128)

Multi-step advance functions (jump-ahead, jump-back)

The method used here is based on Brown, “Random Number Generation with Arbitrary Stride,”, Transactions of the American Nuclear Society (Nov. 1994). The algorithm is very similar to fast exponentiation.

Even though delta is an unsigned integer, we can pass a signed integer to go backwards, it just goes “the long way round”.

Using this function is equivalent to calling `next_64()`

`delta`

number of times.

## Trait Implementations

source### impl Clone for Mcg128Xsl64

### impl Clone for Mcg128Xsl64

source#### fn clone(&self) -> Mcg128Xsl64

#### fn clone(&self) -> Mcg128Xsl64

1.0.0 · source#### fn clone_from(&mut self, source: &Self)

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

`source`

. Read moresource### impl Debug for Mcg128Xsl64

### impl Debug for Mcg128Xsl64

source### impl PartialEq<Mcg128Xsl64> for Mcg128Xsl64

### impl PartialEq<Mcg128Xsl64> for Mcg128Xsl64

source#### fn eq(&self, other: &Mcg128Xsl64) -> bool

#### fn eq(&self, other: &Mcg128Xsl64) -> bool

source### impl RngCore for Mcg128Xsl64

### impl RngCore for Mcg128Xsl64

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

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

`dest`

with random data. Read moresource### impl SeedableRng for Mcg128Xsl64

### impl SeedableRng for Mcg128Xsl64

We use a single 126-bit seed to initialise the state and select a stream.
Two `seed`

bits (lowest order of last byte) are ignored.

#### type Seed = [u8; 16]

#### type Seed = [u8; 16]

`u8`

arrays (we recommend `[u8; N]`

for some `N`

). Read moresource#### fn seed_from_u64(state: u64) -> Self

#### fn seed_from_u64(state: u64) -> Self

`u64`

seed. Read moresource#### fn from_rng<R>(rng: R) -> Result<Self, Error>where

R: RngCore,

#### fn from_rng<R>(rng: R) -> Result<Self, Error>where

R: RngCore,

`Rng`

. Read more