Struct MersenneTwister

pub struct MersenneTwister { /* private fields */ }

Implementation of Mersenne Twister (mt19937ar).

This is a direct Rust port of the C implementation known as mt19937ar.c.

It tries to stay as close as possible to the original in terms of function naming and overall interface. This makes it easier to port libraries that use the Mersenne Twister internally.

The code remains functionally the same but has been cleaned up and re-commented to reflect my own understanding of the original code and algorithm. Some comments from the original have been omitted. Errors are mine.

Implementations

impl MersenneTwister

pub fn new() -> MersenneTwister

Creates a new, unseeded random number generator.

Seed it using init_by_array, init_genrand, or the deprecated and buggy sgenrand.

Trying to generate random numbers without seeding will cause a panic. The upstream implementation automatically seeds the generator using a hardcoded seed instead. To use that seed, you can manually call init_genrand(5489).

pub fn genrand_int32(&mut self) -> u32

This is the core random number generation function that all the others are based on.

It generates a random u32 value.

pub fn init_by_array(&mut self, init_key: &[u32])

Reset the random number generator with a seed of arbitary length.

The seed is specified as a slice of u32 values. It cannot be specified as an iterator because if the seed is shorter than 624 values each value may be accessed more than once.

pub fn init_genrand(&mut self, s: u32)

Reset the random number generator using a single 32 bit seed.

This is generally not recommended since it means all future output of the random number generator can be reproduced by knowing, guessing, or accidentally picking the same 32 bit seed value.

If you want to seed the random number generator with more than 32 bits of data, see init_by_array.

pub fn genrand_res53(&mut self) -> f64

Generates a random value: f64 such that 0. <= value && value < 1., using 53 bits of randomness (the maximum possible for a f64 value).

pub fn genrand_int31(&mut self) -> i32

Generates a random value: i32 such that 0 <= value && value <= 0x7fffffff.

If you want a u32, see genrand_int32.

pub fn genrand_real1(&mut self) -> f64

Generates a random value: f64 such that 0. <= value && value <= 1., using 32 bits worth of randomness.

If you want value < 1 instead of value <= 1, see genrand_real2 (or genrand_res53 if you also want the maximum amount of randomness).

pub fn genrand_real2(&mut self) -> f64

Generates a random value: f64 such that 0. <= value && value < 1., using 32 bits of randomness.

If you want the maximum amount of randomness, see genrand_res53.

pub fn genrand_real3(&mut self) -> f64

Generates a random value: f64 such that 0. < value && value < 1., using 32 bits of randomness.

If you want 0 <= value instead of 0 < value, see genrand_real2 (or genrand_res53 if you also want the maximum amount of randomness).

pub fn sgenrand(&mut self, seed: u32)

👎Deprecated: Can lead to very poor quality random numbers. Use init_by_array or init_genrand instead.

Reset the random number generator using a single 32 bit seed.

This old seed function can cause very poor quality random numbers and is mainly included for historical purposes. It is only present in older versions of the Mersenne Twister code base, not the mt19937ar version this module is based on.

Most software uses init_by_array or init_genrand instead, which were introduced in the mt19937ar version.

Trait Implementations

impl Clone for MersenneTwister

fn clone(&self) -> MersenneTwister

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for MersenneTwister

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

Formats the value using the given formatter.