Is it ensure, insure, or assure?
An iterative algorithm for solving equations. Given an equation,
f x = 0
and an initial approximation, x(0), a better approximation is given by:
x(i+1) = x(i) - f(x(i)) / f'(x(i))
where f'(x) is the first derivative of f, df/dx.
Newton-Raphson iteration is an example of an anytime algorithm in that each approximation is no worse than the previous one.