Thursday, 12 March 2009


My lower sixth are learning about Complex Numbers at the moment and are just about to start representing them on an Argand Diagram. But who was Argand? And why is the diagram named after him?

Jean Robert Argand was an amateur Mathematician born in 1768 in Geneva, Switzerland, but lived and worked in Paris as an accountant in a bookshop.

Argand is credited with the geometric interpretation of complex numbers which bears his name, but he published his ideas in 1806, seven years after Caspar Wessel had published the same idea.

Neither men were mathematicians (Wessel being a surveyor) so their work was not noted until Argand's was picked up by the mathematician, Legendre who passed it to Francois Francais, whose brother, Jacques, republished the work crediting Argand.

Find out the full story and Argand's other contributions to Mathematics at the University of St Andrew's.

Find out more about the Argand Diagram at Wolfram MathWorld including a web demonstration of modulus and argument of a complex number in the Argand diagram.

Waldomaths has some lovely activities to do with complex numbers including the four operations, conjugates and even nth roots of a complex number.

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