Information contentIn information theory, the information content, self-information, surprisal, or Shannon information is a basic quantity derived from the probability of a particular event occurring from a random variable. It can be thought of as an alternative way of expressing probability, much like odds or log-odds, but which has particular mathematical advantages in the setting of information theory. The Shannon information can be interpreted as quantifying the level of "surprise" of a particular outcome.
Synchrotron light sourceA synchrotron light source is a source of electromagnetic radiation (EM) usually produced by a storage ring, for scientific and technical purposes. First observed in synchrotrons, synchrotron light is now produced by storage rings and other specialized particle accelerators, typically accelerating electrons. Once the high-energy electron beam has been generated, it is directed into auxiliary components such as bending magnets and insertion devices (undulators or wigglers) in storage rings and free electron lasers.
Hartley (unit)The hartley (symbol Hart), also called a ban, or a dit (short for decimal digit), is a logarithmic unit that measures information or entropy, based on base 10 logarithms and powers of 10. One hartley is the information content of an event if the probability of that event occurring is . It is therefore equal to the information contained in one decimal digit (or dit), assuming a priori equiprobability of each possible value. It is named after Ralph Hartley.
Shannon (unité)Le shannon est une unité de mesure logarithmique de l'information. L'unité est égale à l'information contenue dans un bit dont la valeur est imprévisible et les deux valeurs également probables. 1 Sh ≈ 0,693 nat ≈ 0,301 . La quantité d'information contenue dans un message est ainsi le nombre de bits minimal pour le transmettre ; soit le logarithme en base 2 du nombre de possibilités de messages différents dans le même code. La compression de données consiste à rapprocher le nombre de bits du nombre de shannons.