Theon taught at the Museum of Alexandria, a cultural and intellectual gathering place that included a number of schools, celebrated library and public lecture halls.
He was not a mathematician of special note, but people indebted to him for an edition of Euclid’s Elements and a commentary of the Almagest; the latter gives a great deal of miscellaneous information about the numerical methods used by the Greeks.
Theon of Alexandria has given a geometrical explanation of the algorithm of the square roots in his Commentary on Ptolemy’s Almagest, while constructing for astronomical use a table of arc lengths, need to calculate the chord of an arc 36°.
Until a little over a century ago, his edition of Euclid’s Elements, on which his daughter Hypatia may have collaborated, was then only known Greek text of the Elements.
He reported that he had observed a solar eclipse at Alexandria in June 16, 364.
Theon of Alexandria (AD 335 – 405)
