PractRand is a random number generator test suite, somewhat like the DIEHARDER and NIST tests I’ve written about before, but more demanding. Rather than running to completion, it runs until it a test fails with an infinitesimally small p -value. It runs all tests at a given sample size, then doubles the sample and runs the tests again. 32-bit generators LCG A while back I wrote about looking for an RNG that would fail the NIST test suite and being surprised that a simple LCG (linear congruential generator) did fairly well. PractRand, however, dismisses this generator with extreme prejudice: RNG_test using PractRand version 0.93 RNG = RNG_stdin32, seed = 0x4a992b2c test set = normal, folding = standard (32 bit) rng=RNG_stdin32, seed=0x4a992b2c length= 64 megabytes (2^26 bytes), time= 2.9 seconds Test Name Raw Processed Evaluation BCFN(2+0,13-3,T) R=+115128 p = 0 FAIL !!!!!!!! BCFN(2+1,13-3,T) R=+105892 p = 0 FAIL !!!!!!!! ... [Low1/32]FPF-14+6/16:(8,14-9) R= +25.8 p =...
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