Repetition of a sequence of instructions. A fundamental part of many algorithms. Iteration is characterised by a set of initial conditions, an iterative step and a termination condition. A well known example of iteration in mathematics is Newton-Raphson iteration. Iteration in programs is expressed using loops, e.g. in C: new_x = n/2 do { x = new_x new_x = 0.5 * (x + n/x) } while (abs(new_x-x) > epsilon) Iteration can be expressed in functional languages using recursion: solve x n = if abs(new_x-x) > epsilon then solve new_x n else new_x where new_x = 0.5 * (x + n/x) solve n/2 n (1998-04-04)
