Jean Paul de Gua de Malves
Encyclopedia
Jean Paul de Gua de Malves (1713, Carcassonne
– June 2, 1785, Paris
) was a French
mathematician
who published in 1740 a work on analytical geometry in which he applied it, without the aid of differential calculus
, to find the tangent
s, asymptote
s, and various singular points
of an algebraic curve
.
He further showed how singular points and isolated loops were affected by conical projection. He gave the proof of Descartes's rule of signs which is to be found in most modern works. It is not clear whether Descartes ever proved it strictly, and Newton
seems to have regarded it as obvious.
De Gua de Malves was acquainted with many of the French philosophes during the last decades of the
Ancien Régime. He was an early, short-lived, participant, then editor (later replaced by Diderot) of the project that ended up as the great Encylopédie
. Condorcet claimed that it was in fact the Abbé who recruited Diderot to the project, though this claim has never been verified. In either case, Jean-Paul and Jean le Rond d'Alembert
, also thought to have been recruited by the Abbé, first show up on the December 1746 payroll of the publishers who were backing the Encylopédie project. Diderot was added just weeks later and took over as editor on 16 October 1747. At the funeral of the "profound geometrician", as Diderot called him, the eulogy was given by Condorcet.
Carcassonne
Carcassonne is a fortified French town in the Aude department, of which it is the prefecture, in the former province of Languedoc.It is divided into the fortified Cité de Carcassonne and the more expansive lower city, the ville basse. Carcassone was founded by the Visigoths in the fifth century,...
– June 2, 1785, Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
) was a French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
who published in 1740 a work on analytical geometry in which he applied it, without the aid of differential calculus
Differential calculus
In mathematics, differential calculus is a subfield of calculus concerned with the study of the rates at which quantities change. It is one of the two traditional divisions of calculus, the other being integral calculus....
, to find the tangent
Tangent
In geometry, the tangent line to a plane curve at a given point is the straight line that "just touches" the curve at that point. More precisely, a straight line is said to be a tangent of a curve at a point on the curve if the line passes through the point on the curve and has slope where f...
s, asymptote
Asymptote
In analytic geometry, an asymptote of a curve is a line such that the distance between the curve and the line approaches zero as they tend to infinity. Some sources include the requirement that the curve may not cross the line infinitely often, but this is unusual for modern authors...
s, and various singular points
Mathematical singularity
In mathematics, a singularity is in general a point at which a given mathematical object is not defined, or a point of an exceptional set where it fails to be well-behaved in some particular way, such as differentiability...
of an algebraic curve
Algebraic curve
In algebraic geometry, an algebraic curve is an algebraic variety of dimension one. The theory of these curves in general was quite fully developed in the nineteenth century, after many particular examples had been considered, starting with circles and other conic sections.- Plane algebraic curves...
.
He further showed how singular points and isolated loops were affected by conical projection. He gave the proof of Descartes's rule of signs which is to be found in most modern works. It is not clear whether Descartes ever proved it strictly, and Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
seems to have regarded it as obvious.
De Gua de Malves was acquainted with many of the French philosophes during the last decades of the
Ancien Régime. He was an early, short-lived, participant, then editor (later replaced by Diderot) of the project that ended up as the great Encylopédie
Encyclopédie
Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers was a general encyclopedia published in France between 1751 and 1772, with later supplements, revised editions, and translations. It was edited by Denis Diderot and Jean le Rond d'Alembert...
. Condorcet claimed that it was in fact the Abbé who recruited Diderot to the project, though this claim has never been verified. In either case, Jean-Paul and Jean le Rond d'Alembert
Jean le Rond d'Alembert
Jean-Baptiste le Rond d'Alembert was a French mathematician, mechanician, physicist, philosopher, and music theorist. He was also co-editor with Denis Diderot of the Encyclopédie...
, also thought to have been recruited by the Abbé, first show up on the December 1746 payroll of the publishers who were backing the Encylopédie project. Diderot was added just weeks later and took over as editor on 16 October 1747. At the funeral of the "profound geometrician", as Diderot called him, the eulogy was given by Condorcet.