Baron Augustin-Louis Cauchy FRS FRSE (UK: /ˈkoʊʃi/ KOH-shee, /ˈkaʊʃi / KOW-shee, US: /koʊˈʃiː / koh-SHEE; French: [oɡystɛ̃ lwi koʃi]; 21 August 1789 – 23 May 1857) was a French mathematician, engineer, and physicist. He was one of the first to rigorously state and prove the key theorems of calculus (thereby creating real analysis), pioneered the field complex analysis, and the study of permutation groups in abstract algebra. Cauchy also contributed to a number of topics in mathematical physics, notably continuum mechanics.
A profound mathematician, Cauchy had a great influence over his contemporaries and successors; Hans Freudenthal stated: