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

10
mean sidereal revolution takes roughly 11.8 years, five
revolutions take 59 mean solar years. The sixtieth year
thereafter of the Jovian Cycle is considered as an Adhi-
Samvatsara thereof so that the luni-Solar reckoning as well
as the jovian reckoning get wedded together. Thus to get
the jovian year we have simply to add 27 to the luni, solar
year. The wedding of the two reckonings has its analogy
in the process of intercalation which weds the solar reckon-
ing with the luni-Solar only with the difference that
months of the latter reckoning are set apart as Adhika
or extra months. Just as the process of intercalation
brings in its train what is called a Kshayamāsa as per the
convention that, that month would be set apart as an
Adhikamāsa, which does not carry a Samkrānti ie entrance
of the Sun into the next Rasi, in which process there
appears a month in which there may occur two Samkrāntis
which is hence considered as a Kshayamāsa, just in a
similar way that luni-Solar year in which the Jupiter
enters the next Rasi, is supposed to be normal whereas that
year in which such an entrance does not take place is
deemed an Ādhika year and set apart while that year which
carries two entrances is deemed as a Kshya year. The pro-
cess of intercalation which weds together the solar and the
luni-solar reckonings will be elucidated further in its appro-
priate context. The word Sāmhitikas means the authors
of the works called Samhitas like the Varāha-Brihatsamhita
etc.
Verse 31. The manushya-māna or that which men
follow, adopts the year, the Ayana the Ṛtu or the season
(six in number during an year) and the yuga according to
the movement of the Sun ie according to Sauramāna the
months and the thithis according to the luni-solar reckon-
ing ie according to Chāndramāna the Vratas, upavāsas,
treatment of diseases, deliveries of ladies, the names of the
weeks all these according to the reckoning of civil days
ie according to Sāvanamāna and finally the ghatis Vighatis
etc. etc. according to the Nākshatramāna.