# Struct rand_pcg::Mcg128Xsl64 [−][src]

pub struct Mcg128Xsl64 { /* fields omitted */ }

## 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

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

This method tests for `self`

and `other`

values to be equal, and is used
by `==`

. Read more

This method tests for `!=`

.

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.