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Prosthaphaeresis (from the Greek προσθαφαίρεσις) was an algorithm used in the late 16th century and early 17th century for approximate multiplication and division using formulas from trigonometry. For the 25 years preceding the invention of the logarithm in 1614, it was the only known generally applicable way of approximating products quickly. Its name comes from the Greek prosthen (πρόσθεν) meaning before and aphaeresis (ἀφαίρεσις), meaning taking away or subtraction.[1][2][3]
In ancient times the term was used to mean a reduction to bring the apparent place of a moving point or planet to the mean place (see Equation of the center). Nicholas Copernicus mentions "prosthaphaeresis" several times in his 1543 work De Revolutionibus Orbium Coelestium, to mean the "great parallax" caused by the displacement of the observer due to the Earth's annual motion.
- ^ prosthaphæresis in The Century Dictionary, The Century Co., New York, 1911.
- ^ Pierce, R. C. Jr. (January 1977). "A Brief History of Logarithms". The Two-Year College Mathematics Journal. 8 (1). Mathematical Association of America: 22–26. doi:10.2307/3026878. JSTOR 3026878.
- ^ Prosthaphaeresis, by Brian Borchers