Guillaume de l'Hôpital
Guillaume François Antoine, Marquis de l'Hôpital (French: [ɡijom fʁɑ̃swa ɑ̃twan maʁki də lopital]; 7 June 1661 – 2 February 1704) was a French mathematician. His name is firmly associated with l'Hôpital's rule for calculating limits involving indeterminate forms 0/0 and ∞/∞.