Joseph-Louis Lagrange

Joseph -Louis de Lagrange ( born January 25, 1736, in Turin as Giuseppe Lodovico Lagrangia, † April 10, 1813 in Paris) was an Italian mathematician and astronomer.

Lagrange established the analytical mechanics ( Lagrange formalism with the Lagrangian ), which he presented in his famous textbook Mécanique analytique 1788. Other fields were the three-body problem in celestial mechanics ( Lagrange points ), the calculus of variations and the theory of complex functions. He made contributions to group theory ( before it existed as a separate branch of research ) and the theory of quadratic forms in number theory. In calculus, the Lagrangian representation of the remainder term of the Taylor formula and in the theory of differential equations, the Lagrange multiplier rule is known.

Life

Lagrange was born Giuseppe Lodovico Lagrangia. His father was a well-placed official of French descent, but by speculation the family suffered significant financial losses. Lagrange visited the Turin School, where he was seventeen the first mathematical interest, after he came across a publication Edmund Halley on first principles. His father wanted him would lawyer, but in the school, Lagrange finally more interested in mathematics, especially geometry. He taught one year all the knowledge of a fully trained mathematician of his time with.

At age 19, he became professor of mathematics at the Royal Artillery School in Turin. In Turin, he published his first scientific papers on differential equations and calculus of variations. In 1757 he is one of the founders of the Turin Academy.

The reputation of Frederick II of Prussia following Lagrange in 1766 was as director of the Prussian Academy of Sciences and successor of Leonhard Euler to Berlin. Here he dealt with problems of astronomy, but also with partial differential equations as well as questions from geometry and algebra.

After the death of Frederick II (1786 ) he went in 1787 as a pensioner of the Academy sc to Paris. After a period of depression appeared as 1788 his well-known work on theoretical physics Mécanique analytique; another publication covers the three-body problem in celestial mechanics.

Began in 1793 in the wake of the French Revolution, the reign of terror and all foreigners were expelled from France. However, Lagrange received an exemption. From 1795 he taught for a short time at the Ecole Normale Supérieure and joined the newly founded Institut de France. From 1797 he taught at the École Polytechnique.

Under Napoleon I, he was appointed to the Count and Senator of France. Thus he met the father of Augustin- Louis Cauchy, and became to a conveyor Cauchy.

Lagrange is laid out in the Panthéon. He is immortalized in particular on the Eiffel Tower (see: The 72 names on the Eiffel Tower ).