RANDU
RANDU is Pseudorandom multiplicative congruential generator (MCG) used during 1960's and 1970's in the IBM Scientific Subroutine Library for IBM System/360 computers.
RANDU uses MCG coeficients multiplier a = 65539 ( 216 + 3 ) and modulus m = 231. It can be implemented very quickly on 32-bit hardware in just 2 operations: wrapping multiplication by a and bit masking of result using AND 0x7fffffff.
Generated values are non negative 31 bit integers. Generator period is 2^29. Lower bits have low randomness and should not be used separately. Problem with lower bits randomness is common for all congruential generators with power of 2 modulus.
RANDU fails the spectral test for dimensions greater than 2. RANDU produces very strong banding when used in 3 dimensions. All points in 3d space fall in 15 two-dimensional planes. This effect can be used in GPU programming for visual effects and take advantage of compute simplicity.
References
https://en.wikipedia.org/wiki/RANDU
https://en.wikipedia.org/wiki/Linear_congruential_generator
License
This is free and unencumbered software released into the public domain.
This code can be used under terms of CC0 or the Unlicense.
