Greek astronomical calendars. V: The motion of the Sun in the Parapegma of Geminos and in the Romaka-Siddhānta (Q1062664)

Greek and Indian texts happen to tell the number of days the Sun needs to move along the Ecliptic by one sign \((30^ 0)\) for each 12 signs. A finite Fourier series can specify this movement in terms of a geocentric eccentric circular orbit. The values of the eccentricity and the apogee derived in this way reveal which particular version of the geocentric theory underlies a given text.