Francois Viete (1540-1603), French mathematician, 17th century engraving. Viete trained as a lawyer, but abandoned the legal profession in 1564 to be a private tutor. He published mainly in mathematics to do with astronomy, and supported the Ptolomaic model instead of the more correct Copernican model of 1543. Viete's work mostly involved algebra and geometry. In 1573, he was appointed to a government post by Charles IX, King of France. Viete served several French kings in the years that followed, variously being in favour, or banished, following the latest political intrigue. At one time, he was employed to decode wartime messages.