=== Aryabhatiya ===
Direct details of Aryabhata's work are therefore known only from the ''[[Aryabhatiya]]''.
The name "Aryabhatiya" is due to later commentators. Aryabhata himself may not have given it a name. His disciple [[Bhaskara I]] calls it ''Ashmakatantra'' ( or the treatise from the Ashmaka). It is also occasionally referred to as ''Arya-shatas-aShTa'' ( literally, Aryabhata 's 108), because there are 108 verses in the text. It is written in the very terse style typical of [[sutra]] literature, in which each line is an aid to memory for a complex system. Thus, the explication of meaning is due to commentators. The text consists of the 108 verses and 13 introductory verses, and is divided into four ''pāda'' s or chapters:
# ''Gitikapada'': (13
verses): large units of time—''kalpa'', ''manvantra'', and ''yuga'' —which present a cosmology different from earlier texts such as Lagadha's ''[[Vedanga Jyotisha]]''( ca. 1st century BCE). There is also a table of sines (''jya''), given in a single verse. The duration of the planetary revolutions during a ''mahayuga'' is given as 4.32 million years.
# ''Ganitapada'' (33
verses): covering mensuration (''kṣetra vyāvahāra''), arithmetic and geometric progressions, [[gnomon]] / shadows (''shanku''-''chhAyA''), simple, [[ quadratic equations| quadratic]], [[ simultaneous equations| simultaneous]], and [[ diophantine equations| indeterminate]] equations (''kuTTaka'')
# ''Kalakriyapada'' (25
verses): different units of time and a method for determining the positions of planets for a given day, calculations concerning the intercalary month (''adhikamAsa''), ''kShaya-tithi'' s, and a seven-day week with names for the days of week.
# ''Golapada'' (50
verses): Geometric/[[ trigonometric]] aspects of the [[ celestial sphere]], features of the [[ ecliptic]], [[ celestial equator]], node, shape of the earth, cause of day and night, rising of [[ zodiacal sign]] s on horizon, etc. In addition, some versions cite a few [[ colophon ( publishing)| colophons]] added at the end, extolling the virtues of the work, etc.
The Aryabhatiya presented a number of innovations in mathematics and astronomy in verse form, which were influential for many centuries. The extreme brevity of the text was elaborated in commentaries by his disciple [[Bhaskara I]] (''Bhashya'', ca. 600 CE) and by [[Nilakantha Somayaji]] in his ''Aryabhatiya Bhasya,'' (1465 CE).
== Matematik ==