In fairness, versine is "archaic" in the "my parents used this when they were in school, but I didn't need to" sense. It only went out of use when people stopp

In fairness, versine is "archaic" in the "my parents used this when they were in school, but I didn't need to" sense. It only went out of use when people stopped using trig tables, replacing them with digital calculators. And of course the actual calculation of this function had to be done (up to a factor of 2) all the time during navigation until things like GPS appeared. See https://en.wikipedia.org/wiki/Haversine_formula https://en.wikipedia.org/wiki/Haversine_formula