The iterated logarithm \(\log^* x\) is defined as the number of iterations of \(\log x\) needed to reach a number less than 1. It is used in computational complexity theory; there are algorithms known to have time complexity \(O(\log^* n)\). \(\log^*\) is so slow-growing that such algorithms practically run in constant time. This article is a . You can help My English Wiki by expanding it.