> After a while of confused debugging, we eventually discovered that the RNG was a linear congruential generator, which, when used the way we did to generate N-

> After a while of confused debugging, we eventually discovered that the RNG was a linear congruential generator, which, when used the way we did to generate N-tuples, tends to produce points that tend to lie on a small number of N-1 dimensional surfaces! Oops. Yep, this is the "Random Numbers Fall Mainly in the Planes" problem that the late George Marsaglia of xorshift fame wrote about in 1968: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC285899/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC285899/ Great paper with one of the best titles I can remember :)