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

88 BRĀHMASPHUṬASIDDHĀNTA & KHAṆḌAKHĀDYAKA
ing of Āryabhaṭa I).¹
(viii) A rule for finding the longitude of the true mean planet
according to midnight-day reckoning is as follows :
Apply half the Śīghraphala and (then) half the
mandaphala to the longitude of the planet's own
mandocca (reversely).
From the resulting longitude of the planet's mandocca cal-
culate the (mandaphala and apply it to mean longitude of the
planet : the resulting longitude of planet is stated to be) the
true-mean longitude of the planet. This is stated to be another
difference (of the midnight day-reckoning) ²
(ix) Length of the circle of the sky and derivation of the
lengths of the orbits of the planets are given as
follows :
Multiply the revolutions of the Moon (in a yuga) by
3, 240,000 and then discard the zero in the unit's place :
(this is the length of the circle of the sky in terms of
yojanas). (Severally) divide that by the revolutions of the
planets (in a yuga): thus are obtained the lengths of the
orbits of the respective planets in terms of yojanas.³
From these stanzas (from 20-35), it is evident that one yojana
of the sunrise day-reckoning is one and a half times that of the
midnight day-reckoning.
Now from stanza 22, it appears that 300 is to be added to
the number of civil days in a Mahāyuga. According to the
Āryabhaṭīya. the number of civil days in this cycle is 1,577,917,
500, which increased by 300, becomes 1,577,917,800, the number of

1. शोधयित्वा क्रमात् पातान् विक्षेपार्शान् प्रसाधयेत् । —31
   योगविश्लेषणोत्पत्तिरेकानेकस्वदिग्वशात् ।
   विक्षेपः स स्फुटो ज्ञेयो ग्रहस्यैकस्य कीर्तितः ॥ —32
   अन्यस्याप्येवमेव स्याच्छेषाः प्रागुक्त कल्पनाः ।
   एतत्सर्वं समासेन तन्त्रान्तरमुदाहृतम् ॥ —MBh. VII. 31 (ii)–33
2. शीघ्रमन्दोच्चचापाधैसंस्कृता त् स्वीयमन्दतः ।
   स्फुटमध्यग्रहः स धै विशेषः परिकीर्तितः ॥ —MBh. VII. 34
3. वेदाश्विरामगुणितान्य युताहतानि ।
   चन्द्रस्य शून्यरहितान्यथ मण्डलानि ॥
   र : स्वैर्हृतानि भगणैः क्रमश्रो ग्रहाणां ।
   कक्ष्या भवन्ति खलु योजनमण्ड्रस्था ॥ —MBh. VII. 35