Asterisk

see also: Etymology of Asterisk

The sign * is called asterisk . One says a asterisk. The word is often marked “ astérix ”, and it is at the origin of the name of the character of Cartoon Astérix. It comes from Latin asteriscus , who comes itself from the Greek ἀστερίσκος asterískos , which means “ small étoile ”. This sign is employed for many différents uses;:

In Typographie, placed after a word it indicates a reference towards a note in bottom of page : for example one can find “ Gentilé * ” in a text with at the foot of the page the mention : “ * this word indicates a name of habitants ”. Different the typographical codes agrees on the use to put a space after the asterisk but not front.

In the dictionaries (TLFi for example), it indicates that a word appears in entry: if one sees “ writes; apple of terre* ”, one is invited to consult the article ground .

Three asterisks can replace a name which one does not want to quote: “ Mrs. of *** ” but this use tends to being replaced by three points: “ Mrs. of… ”.

One also finds “ Mr S *** ” and today “ Mr S… ” with the initial one.

In Linguistic, the asterisk has three distincts uses;:

Placed in front of a word, it announces a restored form, whose existence is deduced but not attestée : “ French infinitive to be comes from Latin spoken *essere corresponding to traditional Latin ess . ”
Placed in front of a syntagm (which can be reduced to only one word), it announces a form agrammaticale (Barbarisme, Solécisme) : “ It happens that a professor finds *chevals in the place of horses in the copies that he corrige. ”
One also uses it like star of Kleene.

In Généalogie one finds “ * ” jointly with “ ° ” which is with being read “ né ” (see Abbreviations in genealogy).

In data processing, the asterisk has four majeurs uses;:

In the languages of Programming, it often symbolizes the multiplication : the operation 3*2 provides the value 6 ; repeated twice it symbolizes then rise with the power : the operation 3 ** 2 provides the value 3² is 9.

DELTA=B ** 2-4*A*C represents the mathematical formula thus Δ=b-4ac .

In C and in certain languages which borrowed this syntax to him, it represents the operation of déréférencement, which gives the value indicated by a pointer. It is also used to represent the type of the pointeurs ; for example, int* means “ pointer towards an object of the int type; ”. The opposite operator is the Esperluette (“ & ”).
In syntaxes like the regular expressions, or the file names, the asterisk announces the repetition of an unspecified number of characters. Examples:

for the files: LED *.tmp is an order which asks for the suppression of all the files ending in .tmp
the regular expression - * identifies an unspecified number of -

One also uses it like star of Kleene.

In the used source language at Wikipédia it is used to introduce an element of not numbered a list known as “ list with puce ”: to see with Syntax wikipédia.

In the forms on the Web, beside a field, it is generally used to specify visually that the field is obligatory.

Use in mathematics

The asterisk has many mathematical uses. It can be used to designate the assistant of an operator. More generally, in noncommutative Geometry, it indicates the involution (generalization of the addition). In theory of the groups, it can be used like symbol of a antimorphism of groups, or to indicate the opposite law.

It is sometimes used to locate a particular value, with the example of a breaking value of a differentiable application.

It can also mean " deprived of 0" : N* = NR \ {0} (=>N private of 0).

The asterisk can have other uses.

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