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

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parallax in longitude to get the moment of apparent
conjunction by the method of successive approximation.
Comm. In as much as the moment of apparent
conjunction for an observer situated somewhere on the
surface of the Earth precedes or follows the moment of
geocentric conjunction being preponed or belated by the
parallax in longitude, we have got to take this parallax
in longitude into account and compute the moment of
apparent conjunction. This computation has to proceed
according to the method of successive approximation since
the hourly motions of the Sun and the Moon vary as well
as the parallax in longitude. When the Sun is in advance
of V, the Sphutalambana advances the Moon more than
the Sun so that the moment of apparent conjunction is
past. Hence the correction is negative and vice versa.
Verses 8 and 9. Computation of the parallax in
longitude without an appeal to the method of successive
approximations.
Let Para = (13 / 32) H cos ZV ; {Para ~ H sin ☉ L}² +
H cos² ☉ L = K² H sin⁻¹ { (H cos ☉ L × Para) / K } =
parallax in longitude.
Ref. fig. 95, E₁ E₂ is taken to be what is termed Para
equal to (4 / R) H cos ZV, H cos ZV being the Vitribha-Sanku.
Since 4 / R could be written as (H sin 24 / R), since 4 ghatis =
(4 × 360) / 60 = 24°, 60 ghatis being equivalent to 360°,
(4 / R) H cos ZV = (H sin 24 / R) × H cos ZV. Imagining for a
moment H cos ZV has come in the place of H sin d