# Achille Marie Gaston Floquet

### Quick Info

Born
15 December 1847
Épinal, France
Died
7 October 1920
Nancy, France

Summary
Gaston Floquet was a French mathematician who worked on mathematical analysis, especially in the theory of differential equations.

### Biography

Gaston Floquet studied at the Lycée Louis-le-Grand in Paris and while there he won a place at the École Normale Supérieure which he entered in 1869. Then in the following year the Franco-Prussian war began which was to prove disastrous for France. The political situation between France and Prussia was deteriorating. The popularity of Napoleon III, the French emperor, was declining in France and he thought a war with Prussia might change his political fortunes since his advisers having told him that the French Army could defeat Prussia. Bismarck, the Prussian chancellor, saw a war with France as an opportunity to unite the South German states. With both sides feeling that a war was to their advantage, the Franco-Prussian War became inevitable. On 14 July, Bismarck sent a telegram aimed at infuriating the French government. He succeeded, for on the 19 July France declared war on Prussia. Floquet joined the army of the Loire as a second lieutenant and fought in war until the signing of the peace treaty when he returned to his studies at the École Normale Supérieure. This was a difficult time for the French were naturally looking for reasons why they lost the war so decisively and the education system too much of the blame. In this difficult atmosphere Floquet completed his studies in 1873 and on the 19 September of that year he was appointed to the Lycée de Belfort where he took charge of the mathematics course.

Floquet obtained his mathematics agrégation on 15 September 1875 and a week later he was named as professor of elementary mathematics at the Lycée d'Angers. On 8 November of the following year Floquet was appointed to the position of professor of special mathematics at the Lycée de Clermont-Ferrand. On 13 February 1878 he was appointed maître de conférences at the Faculty of Science at Nancy. As a result of the Franco-Prussian war which had proved disastrous for France, some French territory had been annexed by Germany and this increased the importance of Nancy. It was situated near the border, and when Floquet arrived there it was a city full of barracks. It also contained many industrialists who had left the annexed territory refusing to become German nationals.

Floquet submitted his doctoral thesis Sur la théorie des équations différentielles linéaires to the Faculty of Science in Paris on 8 April 1879. Much of the work he did over the next few years was based on the ideas which were incorporated in his thesis. For example he published three papers with the title Sur les équations différentielles linéaires à coefficients périodiques , two in 1881 and the third in 1883. In 1884 he published Addition à un mémoire sur les équations différentielles linéaires and Sur les équations différentielles linéaires à coefficients doublement périodiques . The two 1881 papers and the second mentioned paper of 1884 appeared in Comptes Rendus while the others appeared in the Annals of the École Normale Supérieure.

In November 1879 Floquet was given a temporary appointment as a professor at Nancy and in the following year he was put in charge of the mathematics course there. In July 1880 he was given a permanent chair and by the end of the year he was holding the chair of pure mathematics and analysis. He was appointed as head of the Faculty of Science at Nancy in October 1905. He was a very successful head, creating a number of Institutes which helped to make Nancy the leading scientific research centre outside Paris. He continued to publish high quality papers on mathematics and astronomy in Comptes Rendus and in various journals associated with Nancy. For example he published Sur une classe d'équations différentielles linéaires non homogènes (1887), Sur une propriété de la surface $xyz = l^{3}$ (1888), Sur le mouvement d'un fil dans un plan fixe (1889), Sur l'équation de Lamé (1895), Sur le mouvement d'un point ou d'un fil glissant sur un plan horizontal fixe lorsqu'on tient compte de la rotation de la terre et du frottement (1898), Sur les équations intrinsèques du mouvement d'un fil et sur le calcul de sa tension (1901), and L'astronome Messier (1902).

World War I broke out in 1914 and Nancy was heavily shelled. Floquet remained in Nancy during the war, never once leaving the city during the four years to 1918.

### References (show)

1. St Le Tourneur, Floquet (Achille Marie Gaston), Dictionnaire Biographie Française 14 (Paris, 1979), 87.