Marrons mathematician, born in Turin in January 25, 1736 and died in Paris on April 10, 1813. His birth name was Giuseppe Ludovico Lagrangia, although since his youth he/she used the surname of Lagrange.

Self-taught, his numerous studies in various fields of mathematics, especially analysis, became you one of the most important and cherished century mathematicians 18th. Friend of other mathematicians like Euler or D'Alembert, began working in Turin as a professor at the Royal School of artillery, collaborating 1757 in the Foundation of the Academy of Sciences in Turin. In 1766 he/she was appointed director of mathematics of the Academy of Sciences of Berlin, since which was created a varied and fruitful work, and where he/she finished his most important work, Treaty of analytical mechanics (not published until 1788). In 1787 he/she moved to Paris for personal reasons, going on to work for the Academy of Sciences of this city. Among other tasks it formed part of the Committee of weights and measures, introduced the metric system. His work was disturbed but not interrupted by the French Revolution. Abolished the Academy, it gave math classes at the Polytechnic School, at the time that was publishing works on calculation.

He was the eldest of the eleven children of Giuseppe Francesco Ludovico Lagrangia, Treasurer of the Turin public works, and Teresa Grosso. I had French ancestors from his father, which had served under the orders of the Dukes of Savoy, but when he/she was born Turin was the capital of the Italian Kingdom of Piedmont-Sardinia. His father, impoverished after a few bad financial speculations, scheduled him a career as lawyer, who initially accepted. Thus, began his studies at the University of Turin, interested especially for latin, but not for math. However, he/she read a study by the British astronomer Edmond Halley on the possible applications of algebra in the field of optics, which excited him. Also, he/she was attracted by the physics classes taught by Giovanni Battista Beccaria, and decided to finally devote himself to mathematics, he/she learned practically by himself.

Until 1754 it did not finish his first article on the subject, studying the analogies between the theorem of the binomials and the derivatives of a function. Published in form of a letter to the mathematician Giulio Fagnani although submitted before the also mathematician Leonhard Euler, this work had certain consequence of his self-taught training deficiencies. He/She continued undeterred investigating other fields, which gave as a result certain contributions to the calculus of variations; also on this occasion he/she sent its results to Euler (August 1755), which answered shortly afterwards impressed. In September he/she was appointed Professor of mathematics at the Royal School of artillery in Turin. In 1756, a new Exchange of information (in this case on the application of the calculus of variations to mechanics) between Lagrange and Euler, urged this to talk about the first Pierre-Louis of Maupertuis, President of the Academy of Sciences of Paris and the Academy of Sciences of Berlin, which offered a position of prestige in Prussia to Lagrange. Lagrange rejected it, but instead accepted his election as a member of the Berlin Academy (September 2).

The following year, with Angelo Giuseppe, Marquis de Saluces, and G.F.Cigna, he/she was one of the founders of a scientific society in Turin, embryo of the future Academy of Sciences. Among other tasks it dealt with publishing the journal of that society, the Mélanges of Turin ('Turin sundries'), which published several papers on the calculus of variations (of which it can be considered inventor), the calculation of probabilities, the foundations of dynamics, the propagation of the sound (with significant contributions to the calculation of the sequences of vibration, obtaining the same results with other methods but Euler), or about the integration of differential equations, applied to the study of fluid mechanics or the orbits of Jupiter and Saturn. When in 1762 the Academy in Paris announced that the theme of competition for 1764 was the libration of the Moon, Lagrange decided to participate in it, moving to Paris in 1763, where seriously ill because of the intense work that had made the last few years, despite which won the prize and known to scientists as Nicolas de Caritat, Marquis de Condorcet, Jean-Bapiste le Rond d'Alembert or Alexis Claude Clairaut. In 1765 he/she returned to Turin, joining the Academy Award of 1766, this time on the orbits of the moons of Jupiter, which also won.

That same year offered d'Alembert on behalf of King Federico II of Prussia a post at the Berlin Academy, which again rejected Lagrange to not harm his friend Euler. But shortly after this moved to Petersburgo, what finally allowed their acceptance; in November he/she took possession of his post as director of mathematics of the Academy, at the age of thirty years, where he/she remained about 20. Well accomodated locked in general, relationship with Johann Bernoulli; around this time he/she married its prima Vittoria Conti, while they should have children. He/She worked in various subjects (astronomy, calculus, dynamics, mechanics, probability), winning several times the prize of the Paris Academy of Sciences (in 1772, on the three-body problem, shared with Euler; in 1774, again about the Moon, and in 1778, on the disturbances of comets).

Fruit of his work on calculus was the publication in 1770's Réflexions sur la résolution algébrique des equations ('reflections on the algebraic solution of the equations'), which, among others, was the first step in the theory of groups, then studied by Paolo Ruffini, Augustin-Louis Cauchy , and Évariste Galois. In 1781 he/she was offered the direction of the Naples Academy of philosophy, rejected by interested exclusively in mathematics; but in 1783, his wife died after a long illness and Federico II died at the same time in 1786. Thus, fallen into a deep depression, his interest in working in Berlin decreased significantly; He/She received numerous offers from various parts of Italy, France and Spain, but ended up deciding in 1787 by the of the Academy of Sciences of Paris; sponsored by the own there, Queen María Antonieta, he/she would remain until his death, despite the great political turbulence that ensued after because of the French Revolution.

The following year, 1788, finally published one of his most important works, Traité de Mécanique analytique ('mechanical analytical Treaty'), which had ended several years previously in Berlin; in it he/she collected everything related to mechanics from Isaac Newton, this will become a new branch of mathematics. Adrien-Marie Legendretook care of the edition of the work. In 1790 he/she was appointed member of the Academy Committee of standardizing weights and measures according to a metric system, that he/she contributed widely to introduce. In 1792 he/she married Renee-Françoise-Adélaïde Lemonnier, daughter of the astronomer Pierre Charles Lemonnierremarried. The following year was suppressed by order of the Convention the Academy of Sciences, as well as other cultural institutions, but not the Committee of weights and measures, that Lagrange went on to preside over after the expulsion of many of its members, among them Charles Augustin de Coulomb, Pierre Simon de Laplace and Antoine Laurent Lavoisier.

The latter avoided in September that Lagrange, as natural of an enemy country, were arrested; When the own Lavoisier was arrested as a tenant of real taxes, tried in a single day and guillotined on the same evening, Lagrange said dismayed: "just a moment it was enough to make this head, but one hundred years will not be enough to ensure another similar". The was founded in 1794 Paris Polytechnic School (École Polytechnique), was Professor of analysis of this institution, and from 1795, basic math and geometry. But it was not occupation of your choice, because he/she was not gifted to do so despite his vast knowledge. On the other hand, yes it could continue publishing his works, among them two volumes with his lectures on calculus and also théorie des fonctions analytique ('theory of analytical functions', 1797), exposing the principles of the differential calculus. However, it was criticized for its excessive simplification of algebraic calculation, which eliminated in addition the notion of infinity; This was of little use to people who had to apply the calculation, such as architects or engineers, who usually preferred methods of Gottfried Wilhelm Leibniz, although it served as inspiration for studies of other mathematicians as Karl Gustav Jacobi. In 1800 he/she published a complementary work, Leçons sur le calcul des fonctions ('lessons on the calculation of functions').

His scientific activity decreased in the last years of his life, which did not prevent that their accumulated merits will win the homage of the Minister Charles-Maurice of Talleyrand, who in 1808 Napoleón Bonaparte appoint him member of the Legion of honour and a count of the Empire, and in 1813, a few days before his death, was honored with the Grand Cross of the order Imperial of the meeting. It had upon the death of 77 years, being buried in the Pantheon of famous men. Laplace and naturalist Bernard de la Ville, Comte de Lacépède, delivered his funeral oration. Lagrange, of mind abstract and able to apply their methods with great lucidity, was one of the most important mathematicians of the century for his contributions to mathematical analysis, especially on the calculus of variations and differential equations, applied mechanics and astronomy.

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http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Lagrange.html ; Page with a biography and other information about Joseph-Louis Lagrange (in English). http://math.berkeley.edu/~robin/Lagrange/ ; Home on Lagrange, very focused in his mathematical work (in English). http://www.maths.tcd.ie/pub/HistMath/People/Lagrange/RouseBall/RB_Lagrange.html ; Page with another biography of Lagrange (in English). http://www.mat.usach.cl/histmat/html/lagr.html ; Page with more information on Lagrange (in Spanish).