**(January 25, 1736 – April 10, 1813)
**

This Italo-Franco prime mover was born and baptized as Giuseppe Lodovico Lagrangia in Turin, Italy. But the French version of his name is more widely used. Like some of his predecessors, he pursued a career in law before developing interest in mathematics. Despite being largely self-taught, his proficiency enabled him to be appointed a professor in 1755: aged 19. His expertise include: number theory, analysis and mechanics. He was so brilliant and improvising that Leonhard Euler (his former professor) and Jean-Baptiste le Rond d’Alembert recommended him to succeed Euler as the math director of the Berlin Academy of Sciences, in 1766. He spent over 20 years there: producing fantastic works on both maths and mathematical physics. Lagrange returned to France in 1787, joined the French Academy of Sciences; and in the following year, published his highly influential masterpiece, titled:

*Mécanique Analytique*, which he had written while in Berlin. It helped transform both classical and celestial mechanics. His other treatises, which were widely praised, included the

*Theorie des fonctions analytiques*. Afterwards, he became a math professor at the École Polytechnique Paris: when it was established in 1794. Within mathematical analysis, Lagrange researched extensively into the calculus of variations, and in the process, invented the variation of parameters. He also devised ways of using differential calculus to solve problems pertaining to theory of probabilities.