सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

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by x°/10 + x°/88 + Dhruvaka as given by the verse.
Verse 21. To obtain the position of the lunar Node
Rahu.
The Ahargaṇa multiplied by 30 and divided by 566
gives the number of degrees to be added to the Dhruvaka
to give the position of Rahu.
Comm. If the number of the sidereal revolutions of
Rahu in a Kalpa multiplied by twelve divide the number
of days in a Kalpa we have very approximately 566, which
means that Rahu traverses a Rasi very nearly in 566 days.
Hence dividing the Ahargaṇa by 566, and multiplying by
30, we have the degrees covered, which being added to the
Dhruvaka gives the position of Rahu.
Verses 22, 23, 24. Alternative method of obtaining
the planetary positions.
The Ahargaṇa multiplied by 100000, and divided
successively by 101461, 151787, 190833, 24436, 1203400,
62416, 2990000, 898000, 1886800 gives the respective posi-
tions of theplanets beginning from the Sun and those of
the apogee and Node of the Moon; in the case of the
Moon, however, the result is to be multiplied by 20. The
results in degrees added to the Dhruvakas give their posi-
tions.
Comm. The degrees covered by the planets etc in
D days are (R × 360 × D°) / M where R is the number of side-
real revolutions in a Kalpa, M the number of mean solar
days in a Kalpa, and D the Ahargaṇa. Now
(R × 360 × D) / M = (R × 360 × D × 100000) / (M × 100000) = (D × 100000) / ((M × 100000) / (R × 360)) .
Then (M × 100000) / (R × 360) is found for every planet. In the case