Mathematical moments

Jean Robert Argand
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.