Jean-Victor Poncelet

French mathematician. /kloc-0 was born in Metz in July, 788, and/kloc-0 died in Paris on February 22nd, 2008. 18 10 graduated from Paris polytechnic, and then worked as an engineering lecturer in Metz engineering school; 18 12 went to Russia with Napoleon's army and was captured in Si Nuo. During his two years in the prison camp, he recalled and thought about the mathematics he had learned and founded projective geometry. In 18 15, the results obtained in the prison camp are written as projective properties of graphics. 183 1 year, he was elected to the Paris Institute of Science. 1835 became a member of the national defense commission. 1838- 1848 was appointed as a professor of mechanics at the University of Paris, 1848- 1858 was appointed as the president of the Paris Polytechnic, with the rank of general.

Poncelet devoted himself to studying the invariance of the projection of a graph through an arbitrary center, and put forward the concept of cross ratio. The "infinite" element is introduced and systematically developed. He also studied the polar coordinate theory of quadric curves and surfaces, which led to the general duality principle. In addition, he also intuitively discussed the property that a kind of graph keeps continuous change in a certain range, and applied it to virtual elements. His work has a great influence on the development of mathematics in the19th century.