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

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contradistinction to the word Sīghra which we shall
shortly deal with.
In modern astronomy the equation of centre is given
approximately to be equal to 2e sin m where ‘m’ stands for
the mandakendra so that r = 2e. It will be shortly seen
from a subsequent table that this formulation of the equa-
tion of centre gives results which closely accord with their
modern values. The true or apparent positions of the
Sun and the Moon could be obtained fairly well from the
above formulation, so that it is stated that चन्द्रसूर्यौ स्फुटौ
स्यातो मान्देनैकेनकर्मणा i.e., the Moon and the Sun could be re-
ctified by the equation of centre alone.” This is quite in
order for, the Sun and the Moon may be taken to be going
round the Earth in ellipses, with the earth in one focus,
the former relatively and the latter directly.
After having formulated the method of rectification in
the case of the Sun and the Moon, the next question was
with respect to the Tārā grahas i.e. Mercury, Venus and
Mars, Jupiter and Saturn. As these are going round the
Sun and the Sun going round the earth relatively, the
process of rectification got complicated. In the first ins-
tance, the ancient astronomers must have tabulated the
differences between the mean computed positions and the
observed true positions. In the case of Mercury and Venus,
the case appealed different from what it was in the case of
the other three planets, for the simple reason that the
mean positions of the former were taken to coincide with
the mean Sun. This meant that for rectification, the
elongation had to be computed and added to or subtracted
from the mean position of the Sun to get the apparent
geocentric positions of Mercury and Venus. The analogy
of the method of the formulation of the Mandaphala is
taken here also by imagining (1) eccentric circular motion
and (2) postulating an Uccha. In the case of the Manda-
phala, the equation was zero when the mean planet coinci-
ded with the Mandoccha. Here the equation is zero when