ब्राह्मस्फुटसिद्धान्त (ब्रह्मगुप्त - शून्य, कुट्टक, बीजगणित एवं सम्पूर्ण २१ अध्याय सान्वय सटीक)

ĀRYABHAṬA & BRAHMAGUPTA CONTROVERSY 85
commentary on the Brāhmasphuṭasiddhānta we have the
privilege of presenting to the public, it is clear that in certain
respects Bhāskara and others may be wrong but the Āryabhaṭa's
authenticity cannot be questioned. Pṛthūdakasvāmin while
commenting on the Brāhmasphuṭasiddhānta, XI. 26 writes:
Such a mistake may have been made by Bhāskara and
others; they have not understood his (Āryabhaṭa's)
intention.
The passage in the Mahābhāskarīya giving constants of the
ardharātrika system runs as follows (we are giving the translation
from Kripa Shankar Shukla's edition on the Mahābhāskarīya) :
The astronomical processes which have been set forth
above come under the sunrise day - reckoning (audayika
system). In the midnight day-reckoning (ardharātrika
system) too, all this is found to occur: the difference that
exists is being stated (below). ¹
The next fourteen stanzas relate to the midnight day-
reckoning of Āryabhaṭa I.
(i) Civil days and omitted lunar days in a yuga and
revolution numbers of Mercury and Jupiter are thus
given :
(To get the corresponding elements of the midnight
day-reckoning) add 300 to the number of civil days (in
a yuga) and subtract the same (number) from the number
of omitted lunar days (in a yuga); and from the revolution
numbers of (the śīghrocca of) Mercury and Jupiter
subtract 20 and 4 respectively. ²
Thus according to the midnight day-reckoning, we get
civil days in a yuga = 1,577,917,800
omitted lunar days in a yuga = 25,082,280
revolution number of the śīghrocca of
Mercury = 17,937,000
revolution number of Jupiter = 364,220

1. निबन्धः कर्मणां प्रोक्तो योऽसावौदयिको विधिः ।
   अर्धरात्रे त्वयं सर्वो यो विशेषः स कथ्यते ॥ —MBh. VII. 21
2. त्रिशती भूर्दिने क्षेप्या ह्यवमेभ्यो विशोध्यते ।
   ज्ञ गुर्वोर्भगणेभ्योऽपि विंशतिश्च ततोऽब्धयः ॥ —MBh. VII. 22