Jean Frédéric Frenet

Jean Frédéric Frenet (1816 to 1900) was a French mathematician, astronomer and meteorologist, born and died in Périgueux, France. He is best known as an independent co-discoverer of the Frenet-Serret formulas, which describe how the tangent, normal and binormal vectors of a space curve change along the curve and are central to the differential geometry of curves. He wrote six of the nine formulas, which at that time were not expressed in vector notation, and presented them in his doctoral thesis at Toulouse in 1847. That year he became a professor at Toulouse, and in 1848 he became professor of mathematics at Lyon, where he also directed an astronomical observatory. In 1852 he published the formulas in the Journal de Mathématiques Pures et Appliquées. His calculus primer first appeared in 1856 and ran through seven editions, the last of them published after his death, in 1917.