I have not had the time to search the patent
literature systematically; indeed, I decry the current
tendency to seek patents on algorithms.  If somebody
sends me a copy of a relevant patent not presently
cited in this book, I will dutifully refer to it in
future editions. However, I want to encourage people
to continue the centuries-old mathematical tradition
of putting newly discovered algorithms into the public
domain. There are better ways to earn a living than
to prevent other people from making use of one's
contributions to computer science.

        -- Donald E. Knuth
           The Art of Computer Programming, Volume III