Jacques Frédéric Français (20 June 1775 – 9 March 1833) was a French engineer and mathematician.

Biography

Born on 20 June 1775, Jacques Frédéric Français was the son of a grocer of Saverne. He attended the Royal College of Strasbourg and enrolled voluntarily in the

Army of the Rhine An army (from Old French ''armee'', itself derived from the Latin verb ''armāre'', meaning "to arm", and related to the Latin noun ''arma'', meaning "arms" or "weapons"), ground force or land force is a fighting force that fights primarily on ...

in 1793. In September 1794 he was transferred to the military engineering corps. Admitted to the

École Polytechnique École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

in the autumn of 1797, he moved in the spring of 1798 to the École du Génie de Metz and graduated with the brevet of first lieutenant. It was at this time that he wrote about the integration of differential equations. In January 1801 he took part in the

Egyptian Campaign The French campaign in Egypt and Syria (1798–1801) was Napoleon Bonaparte's campaign in the Ottoman territories of Egypt and Syria, proclaimed to defend French trade interests, to establish scientific enterprise in the region. It was the pr ...

of the French Army. On his return in 1801 he was assigned to the port of

Toulon Toulon (, , ; oc, label= Provençal, Tolon , , ) is a city on the French Riviera and a large port on the Mediterranean coast, with a major naval base. Located in the Provence-Alpes-Côte d'Azur region, and the Provence province, Toulon is th ...

. Named captain of the sappers in December 1801, he became second in command of the headquarters of the corps of engineers in November 1802. Under the orders of Admiral Pierre-Charles de Villeneuve, he took part in the naval battles of Cape Finisterre and

Trafalgar Trafalgar most often refers to: * Battle of Trafalgar (1805), fought near Cape Trafalgar, Spain * Trafalgar Square, a public space and tourist attraction in London, England It may also refer to: Music * ''Trafalgar'' (album), by the Bee Gees Pl ...

. In 1807, he was transferred to the regiment of the Colonel Étienne Louis Malus in Strasbourg. He became in 1811 professor of military art at the École d’Application du Génie et de l’Artillerie in

Metz Metz ( , , lat, Divodurum Mediomatricorum, then ) is a city in northeast France located at the confluence of the Moselle and the Seille rivers. Metz is the prefecture of the Moselle department and the seat of the parliament of the Grand ...

until his death in 1833. His mathematical work focused on the study of the changes of Cartesian coordinates applied to systems of planes and lines and the geometric representation of

complex numbers In mathematics, a complex number is an element of a number system that extends the real numbers with a specific element denoted , called the imaginary unit and satisfying the equation i^= -1; every complex number can be expressed in the form ...

based on original ideas of his uncle

Louis François Antoine Arbogast Louis François Antoine Arbogast (4 October 1759 – 8 April 1803) was a French mathematician. He was born at Mutzig in Alsace and died at Strasbourg, where he was professor. He wrote on series and the derivatives known by his name: he was the ...

. They have been published for the most part in the ''

Annales de Gergonne The ''Annales de Mathématiques Pures et Appliquées'', commonly known as the ''Annales de Gergonne'', was a mathematical journal published in Nimes, France from 1810 to 1831 by Joseph Diez Gergonne. The annals were largely devoted to geometry, ...

''. After the death of his brother

François François () is a French masculine given name and surname, equivalent to the English name Francis. People with the given name * Francis I of France, King of France (), known as "the Father and Restorer of Letters" * Francis II of France, Kin ...

;in 1810, he published his treatise ''Recherches sur la poussée des terres'' (1817).

Publications

* ''Mémoire sur le mouvement de rotation d’un corps solide libre autour de son centre de masse'', Paris, 1813

Bibliography

{{DEFAULTSORT:Francais, Jacques Frederic Geotechnical engineers French military engineers French mathematicians 1775 births 1833 deaths