Brahmasphutasiddhanta (Complete Sanskrit Text)

[The rule for calculating the Ahargaṇa number of days elapsed]:
Subtracting two from the elapsed Saka era and dividing by five, take the remaining years.
Double it, and beginning with the bright half of the month of Magha, calculate the Ahargaṇa from the sunrise of that day. [2]
If the [result] added to sixty is [greater than] the lunar date, subtract nine, [then] multiply by the Akshayarka [a constant].
The sky-space-earth numbers 0, 0, 3 representing 300 minus seven gives the lunar position starting with Dhanishtha. [3]
When the conjunction is in the first half of the month, the date is from the north; otherwise, it is the previous date.
Multiplied by the Sun, the Vyatīpāta a period of time during which an eclipse or bad omen may occur [is found] by the Ahargaṇa and [a constant of] five, space, fire 305. [4]
With the doubled fire 3 in the positions, from the north, calculate the day of the yāmyāyana winter solstice period.
The day length is doubled, divided by six, and minus twelve. [5]

According to this, in one yuga age/era, there are 5 solar years = 60 solar months.
Intercalary months = 2. Lunar months = 62. Multiplied by thirty, these are the lunar days = 1860. The omitted days are 30. Excluding these, the Ahargaṇa is 1830.

In the Pañcasiddhāntikā, there is a chapter named "Pauliśa Siddhānta." In the commentary on the Brahmasphuṭasiddhānta, many statements of the Pauliśa Siddhānta have been cited by Pṛthūdaka as evidence. There are many conflicting opinions regarding the author of this treatise. The longitude difference between Yavanapura Alexandria, Ujjain, and Varanasi is mentioned in the Pauliśa Siddhānta cited by Varāha:

The Pauliśa Siddhānta is mentioned in the Brahmasiddhānta of the Śākalyasaṃhitā. In the commentary on the Brahmasphuṭasiddhānta, Pṛthūdaka says, "The longitude line is also read in the Pauliśa." And teacher Pulisha says:

By such considerations, it appears that the Pauliśa Siddhānta was universally accepted. However, this treatise is not currently available. It is the opinion of many scholars that the Sūrya Siddhānta is the most ancient and the first astronomical treatise.

"Some argue that this is different from the perceptible Sun, but that is false and uncertain because that foolish argument lacks validity."