Rene Descartes

History of Ancient Mathematician

René Descartes 31 March 1596– 11 February 1650 (54)

Background • Descartes was born in La Haye en Touraine (now Descartes), France • also known as Renatus Cartesius . • his mother Jeanne Brochard died of tuberculosis when he was one year old. • His father Joachim was a member in the provincial parliament. •

• In Amsterdam, he had a relationship with a servant girl, Helène Jans, with whom he had a daughter, Francine, who was born in 1635 in Deventer • He claimed to be a devout Roman Catholic, however, in his own era, Descartes was accused of harboring secret deist or atheist beliefs. • Died February 11, 1650 (aged 53) Stockholm, Sweden • The cause of death was said to be pneumonia • Main interests Metaphysics, Epistemology, Science, Mathematics

Education • At the age of eleven, he entered the Jesuit Collège Royal Henry-Le-Grand at La Flèche.

• • After graduation, he studied at the University of Poitiers, earning a Baccalauréat and Licence in law in 1616. His father's wishes that he should become a lawyer. • However, his main interest is not in law, so he spent the rest of his youth traveling, visiting courts and armies, mixing with people. • In the summer of 1618 he joined the army

• 10 November 1618, while walking through Breda, Descartes met Isaac Beeckman, who sparked his interest in mathematics and the new physics. • In April 1629 he joined the University of Franeker and the next year, he enrolled at the Leiden University to study mathematics

Influence in Mathematics • the Cartesian coordinate system being named for him. It allows geometric shapes to be expressed in algebraic equations. • He is credited as the father of analytical geometry. • analytical geometry is the bridge between algebra and geometry, crucial to the discovery of calculus and analysis.

• Descartes was also one of the key figures in the Scientific Revolution. 

• His theory provided the basis for the calculus of Newton and Leibniz. • e.g by applying infinitesimal calculus to the tangent line problem, it allows the evolution of that branch of modern mathematics. • Descartes' rule of signs is also a commonly used method to determine the number of positive and negative roots of a polynomial. • discovered an early form of the law of conservation of momentum

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• Descartes also made contributions to the field of optics • He showed by using geometric construction and the law of refraction that the angular radius of a rainbow is 42 degrees. • invented the notation which uses superscripts to show the powers or exponents, for example the 2 used in x2 to indicate squaring. 

Writings Some of his writings : • 1618. Compendium Musicae. A treatise on music theory • 1626–1628. Regulae ad directionem ingenii ( Rules for the Direction of the Mind). • 1630–1633. Le Monde (The World) and L'Homme (Man). Descartes' first systematic presentation of his natural philosophy. • 1637. La Géométrie (Geometry). Descartes' major work in mathematics. 

• 1647. Notae in programma (Comments on a Certain Broadsheet) • • 1644. Principia philosophiae ( Principles of Philosophy), a Latin textbook at first intended by Descartes to replace the Aristotelian textbooks then used in universities. • 1647. The Description of the Human Body .