Born: 18 July 1768 in Geneva, Switzerland

Died: 13 Aug 1822 in Paris, France

Jean-Robert Argand gives hope to all amateur mathematicians. Whilst little

is known about his background, we know that he was an accountant and

bookkeeper in Paris and that as an amateur mathematician he developed the

"Argand diagram" - a geometrical interpretation of complex numbers where

the real part is interpreted as the x-coordinate and the imaginary part as

the y-coordinate.

The Argand diagram is taught to most mathematics students but it is only

through a complex sequence of events that it got the Argand name. The first

to publish this geometrical interpretation of complex numbers was surveyor

Caspar Wessel. The idea appears in Wessel's work in 1787, but it was not

published until 1797, and went unnoticed by the mathematical community

until rediscovered and republished in 1895. You can read more about complex

numbers are how they are represented in our complex number package on Plus:

http://plus.maths.org/issue45/package/index.html

Argand's work too remained obscure for a long time. He first published it

in 1806 in a book produced at his own expense. The book strangely did not

bear his name.

The story continues with Legendre being sent a copy of Argand's work, which

he then sent on to Francois Francais. After Francais's death in 1810, his

brother Jacques worked on his papers and discovered Argand's book. In 1813

Jacques Francais published a work in the Annales de mathematiques in which

he gave a geometric representation of complex numbers based on Argand's

ideas.

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