Dionysius of Cyrene

Dionysius of Cyrene, lived c. 150 BC, was a Stoic philosopher and mathematician.
He was a pupil of Diogenes of Babylon and Antipater of Tarsus.
He was famed as a mathematician, and he is probably the Dionysius whose arguments are attacked by Philodemus in his book On Signs (Latin: De Signis), where Dionysius is reported as arguing that the Sun must be very large because it reappears slowly from behind an obstruction.