1768-1822

French-Swiss mathematician who made important contributions in the area of complex numbers. Although Argand was, by profession, an accountant, he performed some high-quality work in mathematics. Perhaps most important was his geometrical interpretation of complex numbers in which i (the imaginary component) is plotted versus the real component of complex numbers on a plane. Other works included introducing the concept of the modulus of complex numbers and a proof of the fundamental theorem of algebra.