# Struct rand_pcg::Lcg128Xsl64

source ·
[−]`pub struct Lcg128Xsl64 { /* private fields */ }`

## Expand description

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

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

This is a 128-bit LCG with explicitly chosen stream with the PCG-XSL-RR
output function. This combination is the standard `pcg64`

.

Despite the name, this implementation uses 32 bytes (256 bit) space
comprising 128 bits of state and 128 bits stream selector. These are both
set by `SeedableRng`

, using a 256-bit seed.

Note that two generators with different stream parameters may be closely correlated.

## 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.

Construct an instance compatible with PCG seed and stream.

Note that the highest bit of the `stream`

parameter is discarded
to simplify upholding internal invariants.

Note that two generators with different stream parameters may be closely correlated.

PCG specifies the following default values for both parameters:

`state = 0xcafef00dd15ea5e5`

`stream = 0xa02bdbf7bb3c0a7ac28fa16a64abf96`

## 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 255-bit seed to initialise the state and select a stream.
One `seed`

bit (lowest bit of `seed[8]`

) is ignored.

Seed type, which is restricted to types mutably-dereferenceable as `u8`

arrays (we recommend `[u8; N]`

for some `N`

). Read more

Create a new PRNG using a `u64`

seed. Read more

Create a new PRNG seeded from another `Rng`

. Read more

## Auto Trait Implementations

### impl RefUnwindSafe for Lcg128Xsl64

### impl Send for Lcg128Xsl64

### impl Sync for Lcg128Xsl64

### impl Unpin for Lcg128Xsl64

### impl UnwindSafe for Lcg128Xsl64

## Blanket Implementations

Mutably borrows from an owned value. Read more