Jean Robert Argand

JeanRobert Argand was an amateur mathematician. In 1806, while managing a bookstore in Paris, he published the idea of geometrical interpretation of complex numbers known as the Argand diagram and is known for the first rigorous proof of the Fundamental Theorem of Algebra.

JeanRobert Argand was born in Geneva, Switzerland to Jacques Argand and Eve Carnac. His background and education are mostly unknown. Since his knowledge of mathematics was selftaught and he did not belong to any mathematical organizations, he likely pursued mathematics as a hobby rather than a profession.

Source: Wikipedia