Dionysodorus of Kaunos

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Dionysodoros of Kaunos (* around 250 BC in Kaunos ; † around 190 BC) was a Greek mathematician from Asia Minor in the 3rd century BC .

Eutokios mentions him as a mathematician who solved a special cubic equation about the intersection of hyperbola and parabola , that is, of two conic sections. The problem arose from Archimedes' writing About Sphere and Cylinder ( Περὶ σφαίρας καὶ κυλίνδρου Peri sphaíras kai kylíndrou ) . Archimedes asked about a plane that divided a sphere in a certain rational ratio of the radius by a cut. Archimedes put this down to a cubic equation.

Around 1900 Wilhelm Crönert found a papyrus fragment from Herculaneum with a reference to Dionysodorus. Accordingly, Philonides was the pupil of Eudemos of Pergamon - to whom Apollonios of Perge dedicated two books of his work on conic sections and asked him to show them to Philonides. He was followed as the teacher of Philonides Dionysidoros, the son of a Dionysidoros of the same name from Kaunos and possibly an Epicurean . This Dionysodorus was therefore a mathematician. Another fragment says that Philonides published lectures by Dionysidorus. Apollonios was born in Perge , which is near Dionysidoros' birthplace Kaunos. According to Heron of Alexandria (Metrica) he is also the author of a book on the torus , in which, according to Archimedes' methods, the volume of the torus is determined as the product of the circular cross-section and the length of the circular line that describes the center.

According to Vitruvius , a sundial that uses a conic section is said to come from a Dionysidorus . It was reconstructed by Frank W. Cousins. It is likely that this Dionysidorus is also Dionysidoros of Kaunos.

There are other ancient mathematicians of that name. Strabon mentions a Dionysodorus from Amisene on the Black Sea, the area around Amisos , as a mathematician who was known beyond the city and who was known for his erudition. But he lived later. Both were still identified with one another until the beginning of the 20th century. Another Dionysodorus, Dionysodorus of Melos , measured the circumference of the earth to 42,000 stadia according to Pliny the Elder .

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Individual evidence

  1. ↑ Life data according to the assessment by John J. O'Connor, Edmund F. Robertson :  Dionysodoros von Kaunos. In: MacTutor History of Mathematics archive .
  2. ^ Wilhelm Schmidt, About the Greek mathematician Dionysodorus, Bibliotheca Mathematica, Volume 4, 1904, pp. 321-325.
  3. ↑ Frank W. Cousins. Sundials. A Simplified Approach by Means of the Equatorial Dial. John Baker, London 1969.
  4. ↑ Cf. Friedrich Hultsch : Dionysodoros 19 . In: Paulys Realencyclopadie der classischen Antiquity Science (RE). Volume V, 1, Stuttgart 1903, column 1005.
  5. ↑ Pliny, naturalis historia 2,248, cf. to him Friedrich Hultsch: Dionysodorus 20 . In: Paulys Realencyclopadie der classischen Antiquity Science (RE). Volume V, 1, Stuttgart 1903, Col. 1005 f.
personal data
SURNAME Dionysodorus of Kaunos
ALTERNATIVE NAMES Dionysodorus
BRIEF DESCRIPTION Greek mathematician
DATE OF BIRTH around 250 BC Chr.
PLACE OF BIRTH Kaunos
DATE OF DEATH around 190 BC Chr.