En mathématiques et plus particulièrement en analyse et en analyse complexe, la dérivée logarithmique d'une fonction f dérivable ne s'annulant pas est la fonction : où f est la dérivée de f. Lorsque la fonction f est à valeurs réelles strictement positives, la dérivée logarithmique coïncide avec la dérivée de la composée de f par la fonction logarithme ln, comme le montre la formule de la dérivée d'une composée de fonctions.
In complex analysis of one and several complex variables, Wirtinger derivatives (sometimes also called Wirtinger operators), named after Wilhelm Wirtinger who introduced them in 1927 in the course of his studies on the theory of functions of several complex variables, are partial differential operators of the first order which behave in a very similar manner to the ordinary derivatives with respect to one real variable, when applied to holomorphic functions, antiholomorphic functions or simply differentiabl
The law of averages is the commonly held belief that a particular outcome or event will, over certain periods of time, occur at a frequency that is similar to its probability. Depending on context or application it can be considered a valid common-sense observation or a misunderstanding of probability. This notion can lead to the gambler's fallacy when one becomes convinced that a particular outcome must come soon simply because it has not occurred recently (e.g.