 When such behaviour is observed, one talks of scale invariance, self-similarity, or multiscaling.Using so-called "multifractal formalism", it can be shown that, under some well-suited assumptions, there exists a correspondence between the singularity spectrum formula_6 and the multi-scaling exponents formula_20 through a Legendre transform.While the determination of formula_6 calls for some exhaustive local analysis of the data, which would result in difficult and numerically unstable calculations, the estimation of the formula_20 relies on the use of statistical averages and linear regressions in log-log diagrams.