Struct SHR3 

pub struct SHR3 { /* private fields */ }

SHR3 – 3-shift-register random number generator

Reading between the lines, I believe the SHR3 defined in Marsaglia’s 1999 post actually has a typo: the shift values defined don’t actually produce a period of 2^32-1, but have 64 possible cycles, some extremely short. But the swapped values from Marsaglia’s 2003 post produce the full 2^32-1 period. So we use that definition of SHR3.

SHR3 is a 3-shift-register generator with period 2^32-1. It uses y[n]=yn-1(I+R^17)(I+L^5), with the y’s viewed as binary vectors, L the 32x32 binary matrix that shifts a vector left 1, and R its transpose.

Marsaglia says: SHR3 seems to pass all except those related to the binary rank test, since 32 successive values, as binary vectors, must be linearly independent, while 32 successive truly random 32-bit integers, viewed as binary vectors, will be linearly independent only about 29% of the time.

use rand_core::RngCore;
use simplerandom::RngJumpAhead;
let mut s = simplerandom::SHR3::new(1);
let r = s.next_u32();
assert_eq!(r, 270369);
let r = s.next_u32();
assert_eq!(r, 67634689);
let r = s.next_u32();
assert_eq!(r, 2647435461);
let r = s.next_u32();
assert_eq!(r, 307599695);
s.jumpahead(1_000_000);
let r = s.next_u32();
assert_eq!(r, 1105614340);

Implementations

impl SHR3

pub fn new(seed1: u32) -> SHR3

Trait Implementations

impl Clone for SHR3

fn clone(&self) -> SHR3

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SHR3

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for SHR3

fn eq(&self, other: &SHR3) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl RngCore for SHR3

fn next_u32(&mut self) -> u32

Return the next random u32.

fn next_u64(&mut self) -> u64

Return the next random u64.

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

Fill dest with random data.

fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>

Fill dest entirely with random data.

impl RngJumpAhead for SHR3

fn jumpahead<N>(&mut self, n: N)

where N: IntTypes,

impl Eq for SHR3

impl StructuralPartialEq for SHR3