Re: Fonte pour les maths (racine)

["Jean Fontaine" <jfontain AT odyssee.net>]

> Le signe utilisé pour les racines m'a toujours paru bizarre,
esthétiquement
> parlant. Pour pouvoir travailler sur son interpolation, j'aimerais
> comprendre sa nature plus précisément. Quelqu'un peut-il m'en expliquer
> l'origine et la signification ?
>
> Olivier RANDIER

Il y a un bon site sur l'origine des divers symboles mathématiques :

Earliest Uses of Various Mathematical Symbols
http://members.aol.com/jeff570/mathsym.html

Pour l'origine du symbole racine, chercher "square root" vers la fin de
cette page :
http://members.aol.com/jeff570/operation.html

Je copie-colle ci-dessous l'article en question, mais certains symboles et
formats ne seront pas conservés.

Jean Fontaine

Square root. The first use of  was in 1220 by Leonardo of Pisa in Practica
geometriae, where the symbol meant "square root" (Cajori vol. 1, page 90).
The radical symbol first appeared in 1525 in Die Coss by Christoff Rudolff
(1499-1545). He used  (without the vinculum) for square roots. He did not
use indices to indicate higher roots, but instead modified the appearance of
the radical symbol for higher roots.

It is often suggested that the origin of the modern radical symbol is that
it is an altered letter r, the first letter in the word radix. This is the
opinion of Leonhard Euler in his Institutiones calculi differentialis
(1775). However, Florian Cajori, author of A History of Mathematical
Notations, argues against this theory.

In 1637 Rene Descartes used , adding the vinculum to the radical symbol La
Geometrie (Cajori vol. 1, page 375).

Placement of the index within the opening of the radical sign was suggested
in 1629 by Albert Girard (1595-1632) in Invention nouvelle. He suggested
this notation for the cube root (DSB; Cajori vol. 1, page 371).

According to Cajori (vol. 1, page 372) the first person to adopt Girard's
suggestion and place the index within the opening of the radical sign was
Michel Rolle (1652-1719) in 1690 in Traité d' Algébre.

However, a history note in a high school textbook states that the symbol was
first used by Girard "around 1633" (UCSMP Advanced Algebra, 2nd ed., 1996,
page 496).

In the Mathematical Gazette of Feb. 1895, G. Heppel wrote, "Following
Chrystal, Todhunter, Hall and Knight, and the majority of writers [sqrt]a
should be considered a quantity having one and not two values, although the
algebra of C. Smith and the article by Professor Kelland in the Encyclopedia
Britannica make [sqrt]a have two values."

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