1. Circuitry for computing a first trigonometric function of an input, said circuitry comprising: circuitry for relating said input to another value to generate an intermediate value; circuitry for selecting one of said input and said intermediate value as a trigonometric input value; circuitry for determining respective initial values of a plurality of trigonometric functions for said trigonometric input value; and circuitry for deriving, based at least in part on a trigonometric identity, a final value of said first trigonometric function from said respective initial values of said plurality of trigonometric functions.