Random

A collection of Pseudo Random Number Generators (PRNG) algorithms for the Crystal language. Each implementation implements the Random interface.

Continuation of the crystal-random shard.

Installation

Add the shard:

dependencies:
  random:
    github: ysbaddaden/random.cr

Usage

You may require random/all to include all algorithms, but it is recommended to specify the chosen algorithms such as random/xorshift128plus for example.

Algorithms

Sorted by increasing state.

|PRNG |w |speed (x86)|speed (arm)|State |Splittable|Cryptography|TestU01 |Comment| |-----------------------------|------|-----------|-----------|----------|----------|------------|-----------|-------| |Random::XorShift32 |32-bit|4.01ns |3.24ns |2$^{32} |No |No |Fails |too many TESTU01 failures| |Random::ISAAC (stdlib) |32-bit|8.02ns |8.71ns |2$^{64} |No |Yes |- || |Random::PCG32 (stdlib) |32-bit|4.41ns |3.77ns |2$^{64} |No |No |Big Crush || |Random::PCG64 |64-bit|4.47ns |7.20ns |2$^{64} |No |No |? || |Random::SplitMix64 |64-bit|3.77ns |4.13ns |2$^{64} |No |No |Big Crush |used to seed XoShiRo128 and XoShiRo256| |Random::Splittable |64-bit|3.46ns |3.91ns |2$^{64} |Yes |No |Big Crush || |Random::XorShift64 |64-bit|3.55ns |2.52ns ! |2$^{64} |No |No |Fails || |Random::XorShift64Plus |32-bit|4.47ns |3.77ns |2$^{64} |No |No |Small Crush|for Float32 numbers| |Random::XorShift64Star |64-bit|3.51ns |3.01ns |2$^{64} |No |No |Fails |for Float64 numbers| |Random::XoRoShiRo64StarStar|32-bit|4.75ns |4.10ns |2$^{64} |No |No |Big Crush |all purpose generator| |Random::WyRand |64-bit|3.15ns ! |5.18ns |2$^{64} |No |No |Big Crush || |Random::Lehmer64 |64-bit|3.15ns ! |5.53ns |2$^{128} |No |No |Big Crush |simplest| |Random::Splittable128 |64-bit|4.24ns |4.70ns |2$^{128} |Yes |No |Big Crush || |Random::XorShift128 |32-bit|5.97ns |4.89ns |2$^{128} |No |No |Fails || |Random::XorShift128Plus |64-bit|3.38ns |2.91ns |2$^{128} |No |No |? |for Float64 numbers| |Random::XoShiRo128StarStar |32-bit|5.23ns |4.15ns |2$^{128} |Yes |No |Big Crush |all purpose generator| |Random::XoShiRo128Plus |32-bit|5.04ns |4.28ns |2$^{128} |Yes |No |? |for Float32 numbers| |Random::XoShiRo256PlusPlus |64-bit|4.07ns |3.60ns |2$^{256} |Yes |No |Big Crush |all purpose generator| |Random::XoShiRo256StarStar |64-bit|3.97ns |3.50ns |2$^{256} |Yes |No |Big Crush |all purpose generator| |Random::XoShiRo256Plus |64-bit|3.90ns |3.76ns |2$^{256} |Yes |No |? |for Float64 numbers| |Random::XorShift1024Star |64-bit|3.77ns |4.00ns |2$^{1024} |Yes |No |Fails |for massive parallel computations| |Random::MT19937 |32-bit|6.64ns |5.13ns |2$^{19937}|No |No |Fails |Mersenne Twister (removed from stdlib)|

The Plus and Star scrambles for the xorshift family (including xoshiro and xoroshiro) all fail BigCrush, but are still statistically correct enough to generate floating-point numbers (either Float32 or Float64) since their weakest bits are skipped.

The algorithms were benchmarked on an Intel Core i7-4712HQ (Haswell) and an Neoverse-N1 ARM server.

The TESTU01 results are aggregated from the following pages by Sebastiano Vigna and Daniel Lemire, as well as different papers.

• https://prng.di.unimi.it/
• https://github.com/lemire/testingRNG
• https://arxiv.org/pdf/1402.6246
• https://arxiv.org/pdf/1404.0390

TODO:

• [ ] Random::ISAAC64
• [ ] Random::ChaCha12
• [ ] Random::ChaCha20

Maybe also:

• [ ] Random::MWC128
• [ ] Random::MWC256
• [ ] Random::MWC512
• [ ] Random::GMWC128
• [ ] Random::GMWC256
• [ ] Random::WELL512
• [ ] Random::WELL1024
• [ ] Random::WELL19937
• [ ] Random::WELL44497
• [ ] Random::XorWow
• [ ] Random::XoRoShiRo64Star
• [ ] Random::XoRoShiRo128Plus
• [ ] Random::XoRoShiRo128PlusPlus
• [ ] Random::XoRoShiRo128StarStar
• [ ] Random::XoShiRo512Plus
• [ ] Random::XoShiRo512PlusPlus
• [ ] Random::XoShiRo512StarStar
• [ ] Random::XoRoShiRo1024PlusPlus
• [ ] Random::XoRoShiRo1024StarStar
• [ ] Random::XoRoShiRo1024Star

License

Distributed under the Apache-2.0 license.

Contributors

• Julien Portalier (@ysbaddaden)
• crystal-lang The Crystal Lang Team - creator, maintainer