A difference engine, a calculating machine designed in the 1820s, was first created by Charles Babbage. Difference engines are automatic mechanical calculators designed to tabulate polynomial functions. The name, the difference engine, is derived from the method of divided differences, a way to interpolate or tabulate functions by using a small set of polynomial co-efficients. Some of the most common mathematical functions used in engineering, science and navigation, were, and still are able to be computed with the use of the difference engine's capability of computing logarithmic and trigonometric functions, which can be approximated by polynomials, so a difference engine can compute many useful tables of numbers.
