The most surprising Unix programs
« Typo was as surprising inside as it was outside. Its similarity measure was based on trigram frequencies, which it counted in a 26x26x26 array. The small memory, which had barely room enough for 1-byte counters, spurred a scheme for squeezing large numbers into small counters. To avoid overflow, counters were updated probabilistically to maintain an estimate of the logarithm of the count. »This sounds like something from the same family as hyperloglogWikipedia traces that back to the Flajolet–Martin algorithm in 1984. When would typo have been written?