abstract
It has been known for 30 years that pseudorandom number generators
in the class of \emph{linear congruential generators} (LCG)
exhibit strong and predictable regularities. A widely
used generator in this class is \texttt{drand48}. While the regularity is
not problematic in most applications, I show that it can produce very
misleading results in testing geometric algorithms that involve determinant
computations. By presenting scenarios where LCG behave `nonrandom' (sometimes
in a spectacular way), I want to raise awareness for possible problems with
LCG and pseudorandom numbers in general.
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