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

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for Koti are √(R+r - g²- β²) / (u - v) and (T - I) (u - v). When I
is given we have to use the latter formula and take T" in
the place of T where T, T' and T" are respectively the
Sthityardhas (1) Mean, (2) Mean rectified for parallax in
latitude and (3) Mean rectified for parallax in longitude.
Of course here to arrive at T", method of successive
approximation is to be used as β goes on changing from
time to time and there is an inter-play between the
simultaneous effects of parallax in longitude and that in
latitude.
On the other hand when g is given we have to use the
former formula for the Koti and the Koti thus obtained
is to be rectified for the variation in β. So Sūryasiddhānta
proposes the formula
√(R+r - g)² - β² / (u - v) × T' / T" meaning thereby that the correction
for the variation in β is more important because the
formula is in terms of β and not the other formula. This
formulation is approximate but adopted for the sake of
ease. Otherwise from the grāsa, I is to be obtained and
the other formula could be used which method is more
laborious.
Bhāskara's Correction of Brahmagupta's Statement
Verses 1, 2 & 3. The statement of Brahmagupta
namely that the arc of the Moon's Dṛk-kṣepa will be
obtained by the sum or difference of that of the Sun with
the latitude of the Vitribha, I (Bhāskara) do not accept.
I shall give the reason why. In a place where the
latitude is 24°, when the longitudes of the Sun, the Moon
and the Node are all 180°, at the time of Sun-rise, the
ecliptic occupies the position of the prime-vertical. The
Moon will not leave the ecliptic even though depressed by
parallax in longitude. Thus there is no parallax in