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

58
Comm. The lord of the year is the lord of the week-
day at the Commencement of the solar year. To get this
week-day we have if the number of Tithis elapsed upto the
beginning of the luni-solar year be T, the Suddhi S', the
Kshayāhās upto the Commencement of the solar year be K,
then since the number of civil days is equal to T + K, R₇
(civil days) = R₇ (T + S — K). But T = 360y + 30A where
y is the number of elapsed solar years and A the number of
elapsed Adhikamāsās. ∴ R₇ (T) = R₇ (360y + 30A) = R₇
(3y + 2A) since the remainder got by dividing 360 and 30
by seven are respectively 3 and 2. Hence R₇ (civil days =
Ahargaṇa) = R₇ (3y + 2A) + R₇S' — R₇K. The number of
Kshayāhās K = y (5-48-22-7-30) = 5y + y (0-48-22-7-30).
But y (0-48-22-7-30) = K where K is the previously calcu-
lated Kshayāhādya. Hence R₇K = R₇5y + R₇K. Substi-
tuting this in the above R₇ (civil days) = R₇ (3y + 2A) +
R₇S' — R₇ (5y + K) = R₇S' — R₇ (5y — 3y) + R₇ (2A) —
R₇K = R₇ [S' — R₇ (2y — 2A) — R₇K ] which is the given
formula = R₇ [S — R₇ (2y — 2A + K) ].
Verse 8. To obtain the fractional part of the elapsed
Kshayāhās even without a knowledge of the number of
Kshayāhās.
The excess of the ghatis of the Adhimāsa Sesha ie the
remainder got by dividing the sum of the Dinādya, Ksha-
yāhādya and ten times the number of elapsed years by 30 as
indicated in verse 5, over the ghatis of the Dinādya, obtai-
ned under verse 1 gives the fractional part of the Kshayāhās.
Comm. The ghatis or the fractional part of the Adhi-
māsa Sesha is the-sum of the fractional parts of Dinādha
and the Kshayāhādya so that the [excess of the ghatis of
the Adhimāsa Sesha over the ghatis or the fractional part
of the Dinādya gives the ghatis or [the fractional part of
the Kshayāhās.
Verse 9. The planetary positions at the end of the
elapsed solar year.