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

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city of a mortal. Hence great astronomers accept such an
āgama as would give results which accord with observations
during their times, and such a one as was formerly accepted
by a very intelligent astronomer. Then they produce their
own works exhibiting their own Skill in the Science and
refuting wrong notions of others. Their idea is 'Let the
Āgama we take as an authority be whatever it would be
Let us show our own skill in the course of our work', just
as in this work, the āgama accepted by Brahmagupta is
taken on faith as the authority. Then it might be argued
"Better not attempt at trying to prove how the numbers
of sidereal revolutions were arrived at. Even if a proof be
attempted, that proof would be obsessed by the ' Itarētara-
śrayadōṣa' (cited above). Nevertheless we shall give a
brief proof, That 'itarētarāśrayadōṣa' is apparently a
dōṣa i.e. an apparent defect; for, different proofs could
not be adduced simultaneously. The proof will now be
given".
These words indicate that even such a highly rational
and supremely intelligent astronomer like Bhāskara could
not set aside his faith in our āgama and attempt at a pure
and rigorous proof, which would not invoke the āgama-Let
us see where in his proof he does commit the so-called
itarētarāśrayadōṣa and where he invokes the āgama.
Also we shall try to construct a proof, of course to a good
extent on the lines on which Bhāskara tries to give his
proof, but at the same we shall not invoke the āgama.
where he does, but try to proceed purely on a rational basis.
We shall take up the proof under verse 18, in its appropriate
context. We shall now proceed with the text upto that
point, which gives a brief sketch of the Hindn trigono-
metry.