Dr. Evelyn Lamb, writing for Scientific American:
On Monday, the Onion reported that the “Nation’s math teachers introduce 27 new trig functions.” It’s a funny read. The gamsin, negtan, and cosvnx from the Onion article are fictional, but the piece has a kernel of truth: there are 10 secret trig functions you’ve never heard of, and they have delightful names like “haversine” and “exsecant.”
I have actually used haversine in some mapping code written while in grad school. The others were new to me.
(via: Scholar and gentleman, Brian Bridges)