Prosthaphaeresis

Prosthaphaeresis was an algorithm used in the late 16th century and early 17th century for approximating products 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 prosthesi and afairo, meaning addition and subtraction, two steps in the process.

Sources

• PlanetMath: Prosthaphaeresis formulas
• Daniel E. Otero Henry Briggs. Introduction: the need for speed in calculation.
• Mathworld: Prosthaphaeresis formulas
• Adam Mosley. Tycho Brahe and Mathematical Techniques. University of Cambridge.
• IEEE Computer Society. History of computing: John Napier and the invention of logarithms.
• Math Words: Prosthaphaeresis
• Beatrice Lumpkin. African and African-American Contributions to Mathematics. Discusses Ibn Yunis's contribution to prosthaphaeresis.
• David B. Sher and Dean C. Nataro.The Prosthaphaeretic Slide Rule: a mechanical multiplication device based on trigonometric identities. Math and Computer Education, Vol. 38 #1, Spring 2004, pp. 37-43.