Sylvestre-François Lacroix
See also: Lacroix
Sylvestre-François Lacroix (born in Paris on April 28th 1765 - † in Paris on May 24th 1843) is a French mathematician of which the " Treaty of differential calculus and calculation intégral" a very great influence at the XIXe century had.
Biography
Resulting from a modest Parisian family, Lacroix was likely to be able to follow the courses of Gaspard Monge, whereas this geometrician had just joined the capital with the favor of his nomination to the Academy of Science. It was about a course of analyzes applied to the geometry (analytical geometry), that Monge exempted with the pulpit Hydrodynamique of Louvre. Lacroix showed such provisions for mathematics which its professor, who had just taken again the load of inspector at the school of the juniors by the Navy (to replace Etienne Bézout) made name it mathematics professor at the School of the Guards of Navy of Rochefort since 1782. Monge did not teach however the descriptive Géométrie to him, because the methods of this discipline (double projection, raising, folding back, plans tangent) were held like a military secrecy.Lacroix suspected however the existence of a discipline allowing the geometrical solution of problems of Solid geometry. At the time of its stay in Besancon, it penetrated the principles of the geometry of Monge thanks to the indications given by two former students of the royal École of the genius of Wall in garrison in the Jura, Justin Girod de Chantrans and Charles d' Amondans de Tinseau.
It went back then to Paris some time to afterwards teach there astronomy and mathematics with the College, then with the Military academy. In August 1788, it was recruited as mathematics professor, of physics and chemistry at the Artillery School of Besancon. Inspector of the artillery body in 1793 to replace Pierre-Simon Laplace, it was chosen by Monge like assistant for the course of descriptive Géométrie given to transitory the National university. As from 1799, its nomination as mathematics professor at the Polytechnic school leads it to write the majority of its courses, with the idea to improve them. He is elected the same year with the National institute of Sciences and Arts. He gave his first conferences to the Collège de France since 1812 but became titular pulpit of mathematics of this institution only in 1815. He was also the first holder of the pulpit of differential and integral calculus of the Faculty of Science of Paris.
The works of Lacroix knew a broad diffusion at the XIXe century, both in Italy and in England: they were still used more than fifty years after their drafting.
A crater of the Moon was named in its honor.
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