Crate rand_xoshiro

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This crate implements the xoshiro family of pseudorandom number generators designed by David Blackman and Sebastiano Vigna. They feature high perfomance and a small state and superseed the previous xorshift-based generators. However, they are no cryptographically secure and their output can be predicted by observing a few samples.

The following generators are implemented:

§64-bit generators

  • Xoshiro256StarStar: Recommended for all purposes. Excellent speed and a state space (256 bits) large enough for any parallel application.
  • Xoshiro256PlusPlus: Recommended for all purposes. Excellent speed and a state space (256 bits) large enough for any parallel application.
  • Xoshiro256Plus: Recommended for generating 64-bit floating-point numbers. About 15% faster than Xoshiro256StarStar, but has a low linear complexity in the lowest bits (which are discarded when generating floats), making it fail linearity tests. This is unlikely to have any impact in practise.
  • Xoroshiro128StarStar: An alternative to Xoshiro256StarStar, having the same speed but using half the state. Only suited for low-scale parallel applications.
  • Xoroshiro128PlusPlus: An alternative to Xoshiro256PlusPlus, having the same speed but using half the state. Only suited for low-scale parallel applications.
  • Xoroshiro128Plus: An alternative to Xoshiro256Plus, having the same speed but using half the state. Only suited for low-scale parallel applications. Has a low linear complexity in the lowest bits (which are discarded when generating floats), making it fail linearity tests. This is unlikely to have any impact in practise.
  • Xoshiro512StarStar: An alternative to Xoshiro256StarStar with more state and the same speed.
  • Xoshiro512PlusPlus: An alternative to Xoshiro256PlusPlus with more state and the same speed.
  • Xoshiro512Plus: An alternative to Xoshiro512Plus with more state and the same speed. Has a low linear complexity in the lowest bits (which are discarded when generating floats), making it fail linearity tests. This is unlikely to have any impact in practise.
  • SplitMix64: Recommended for initializing generators of the xoshiro familiy from a 64-bit seed. Used for implementing seed_from_u64.

§32-bit generators

  • Xoshiro128StarStar: Recommended for all purposes. Excellent speed.
  • Xoshiro128PlusPlus: Recommended for all purposes. Excellent speed.
  • Xoshiro128Plus: Recommended for generating 32-bit floating-point numbers. Faster than Xoshiro128StarStar, but has a low linear complexity in the lowest bits (which are discarded when generating floats), making it fail linearity tests. This is unlikely to have any impact in practise.
  • Xoroshiro64StarStar: An alternative to Xoshiro128StarStar, having the same speed but using half the state.
  • Xoroshiro64Star: An alternative to Xoshiro128Plus, having the same speed but using half the state. Has a low linear complexity in the lowest bits (which are discarded when generating floats), making it fail linearity tests. This is unlikely to have any impact in practise.

The *PlusPlus generators perform similarily to the *StarStar generators. See the xoshiro paper, where the differences are discussed in detail.

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