Charles-Ange Laisant (1 November 1841 – 5 May 1920), French politician and mathematician, was born at

Indre Indre (; oc, Endre) is a landlocked department in central France named after the river Indre. The inhabitants of the department are known as the ''Indriens'' (masculine; ) and ''Indriennes'' (feminine; ). Indre is part of the current administ ...

, near

Nantes Nantes (, , ; Gallo: or ; ) is a city in Loire-Atlantique on the Loire, from the Atlantic coast. The city is the sixth largest in France, with a population of 314,138 in Nantes proper and a metropolitan area of nearly 1 million inhabita ...

on 1 November 1841, and was educated at 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 ...

as a military engineer. He was a Freemason and a libertarian socialist.

Politics

He defended the fort of

Issy Issy-les-Moulineaux () is a commune in the southwestern suburban area of Paris, France, lying on the left bank of the river Seine. Its citizens are called ''Isséens'' in French. It is one of Paris' entrances and is located from Notre-Dame Cath ...

at the Siege of Paris, and served in

Corsica Corsica ( , Upper , Southern ; it, Corsica; ; french: Corse ; lij, Còrsega; sc, Còssiga) is an island in the Mediterranean Sea and one of the 18 regions of France. It is the fourth-largest island in the Mediterranean and lies southeast of ...

and in

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in 1873. In 1876 he resigned his commission to enter the

Chamber Chamber or the chamber may refer to: In government and organizations * Chamber of commerce, an organization of business owners to promote commercial interests *Legislative chamber, in politics * Debate chamber, the space or room that houses delib ...

as deputy for

in the republican interest, and in 1879 he became director of the ''

Le Petit Parisien ''Le Petit Parisien'' was a prominent French newspaper during the French Third Republic. It was published between 1876 and 1944, and its circulation was over two million after the First World War. Publishing Despite its name, the paper was circu ...

''. For alleged

libel Defamation is the act of communicating to a third party false statements about a person, place or thing that results in damage to its reputation. It can be spoken (slander) or written (libel). It constitutes a tort or a crime. The legal defini ...

on General Courtot de Cissey in this paper he was heavily fined. The Encyclopaedia Britannica article has the erroroneous "Anne" for the correct "Ange". In the Chamber he spoke chiefly on army questions; and was chairman of a commission appointed to consider army legislation, resigning in 1887 on the refusal of the Chamber to sanction the abolition of exemptions of any kind. He then became an adherent of the revisionist policy of

General Boulanger Georges Ernest Jean-Marie Boulanger (29 April 1837 – 30 September 1891), nicknamed Général Revanche ("General Revenge"), was a French general and politician. An enormously popular public figure during the second decade of the Third Repub ...

and a member of the

League of Patriots The League of Patriots (french: Ligue des Patriotes) was a French Far-right leagues, far-right league, founded in 1882 by the French nationalism, nationalist poet Paul Déroulède, historian Henri Martin (historian), Henri Martin and politician F� ...

. Laisant published two political pamphlets, ''Pourquoi et comment je suis Boulangiste'' (1887) and ''L'Anarchie bourgeoise'' (1887). He was elected Boulangist deputy for the 18th Parisian arrondissement in 1889.

Mathematics

Laisant did not seek re-election in 1893, but devoted himself thenceforward to

mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...

. Already in 1874, he published a survey on

hyperbolic function In mathematics, hyperbolic functions are analogues of the ordinary trigonometric functions, but defined using the hyperbola rather than the circle. Just as the points form a circle with a unit radius, the points form the right half of the u ...

s as well as a French translation of Giusto Bellavitis main paper on equipollences into which Laisant added a chapter on

hyperbola In mathematics, a hyperbola (; pl. hyperbolas or hyperbolae ; adj. hyperbolic ) is a type of smooth curve lying in a plane, defined by its geometric properties or by equations for which it is the solution set. A hyperbola has two pieces, cal ...

s. He published two works in geometric algebra, ''Introduction à la Méthode des Quaternions'' (1881) and ''Théorie et applications des equipollences'' (1887). He also co-founded a mathematical journal, '' L'Intermédiaire des Mathématiciens'' with

Émile Lemoine Émile Michel Hyacinthe Lemoine (; 22 November 1840 – 21 February 1912) was a French civil engineer and a mathematician, a geometer in particular. He was educated at a variety of institutions, including the Prytanée National Militaire and, mo ...

in 1894, and was in 1888 the president of the

Société Mathématique de France Lactalis is a French multinational dairy products corporation, owned by the Besnier family and based in Laval, Mayenne, France. The company's former name was Besnier SA. Lactalis is the largest dairy products group in the world, and is the sec ...

.Anciens Présidents de la SMF — 1873–2006
. The

quaternion In mathematics, the quaternion number system extends the complex numbers. Quaternions were first described by the Irish mathematician William Rowan Hamilton in 1843 and applied to mechanics in three-dimensional space. Hamilton defined a quatern ...

textbook was an abridgement of one by

Jules Hoüel Guillaume-Jules Hoüel (7 April 1823 – 14 June 1886) was a French people, French mathematician. He entered the École Normale Supérieure in 1843 and received his doctoral degree in 1855 from the University of Paris, Sorbonne. He was sought by ...

, and the text on equipollence further expanded on Bellavitis' methods. He was attached to the staff of the École Polytechnique, and in 1903–1904 was president of the French Association for the Advancement of Science. The pedagogical journal, L'Enseignement Mathématique, founded by Laisant and

Henri Fehr Henri Fehr (Zurich, 2 February 1870 – Geneva, 2 November 1954) was a Swiss mathematician. He was the founder of the Foundation for the Advancement of Mathematical Sciences, of the journal " Commentarii Mathematici Helvetici" and of the journal ...

in 1899, became the official organ of the

International Commission on Mathematical Instruction The International Commission on Mathematical Instruction (ICMI) is a commission of the International Mathematical Union and is an internationally acting organization focussing on mathematics education. ICMI was founded in 1908 at the International ...

in 1909.,

References

External links

* {{DEFAULTSORT:Laisant, Charles-Ange 1841 births 1920 deaths Scientists from Nantes Politicians from Nantes French anarchists 19th-century French mathematicians 20th-century French mathematicians French Esperantists École Polytechnique alumni

Politics

Mathematics

See also

References

External links