Arlet Ottens

I've seen some failures reported on other tests (I remember MaxOft) as well, but with p-values around 1e-4, so not really definitive. The birthday spacings is the one that fails hard. I'll keep an eye on other results. In my code, the 48 bit LCG portion is fixed, and the 32 bit hash sequence is generated by an algorithm that tries out random sequences of candidate instructions . Each generator is then tested by calling PractRand, which I have modified to return a simple quality score. The set of...

Possibly related: I noticed this issue while working on a project to create a good PRNG for 8 bit targets, using a genetic/hill climbing algorithm that uses PractRand to test candidates. I've seen it happen quite regularly that PractRand gives a pass for 128GB or even 1TB, but that the same PRNG output fails in SmallCrush/Crush, usually on the BirthdaySpacings test. The same thing happened with the output files above. The contrast between PractRand running for an hour or more and seeing no problems...

Both files fail SmallCrush: ~~~ ========= Summary results of SmallCrush ========= Version: TestU01 1.2.3 Generator: stdin Number of statistics: 15 Total CPU time: 00:00:06.00 The following tests gave p-values outside [0.001, 0.9990]: (eps means a value < 1.0e-300): (eps1 means a value < 1.0e-15): Test p-value 1 BirthdaySpacings eps All other tests were passed

Different results when 1 byte is skipped