Editing Lalla

{{Short description|Indian mathematician, astronomer and astrologer (720–790)}}
{{for|other people named Lalla|Lalla (disambiguation)}}
{{Infobox scientist
| name        = Lalla
| birth_date  = 720
| birth_place = [[Gujarat]]
| death_date  = 790
| death_place = [[India]]
}}
'''Lalla''' ({{circa}} 720–790 CE) was an Indian [[Indian mathematics|mathematician]], [[astronomer]], and [[astrologer]] who belonged to a family of astronomers. Lalla was the son of Trivikrama Bhatta and the grandson of Śâmba.<ref name="ReferenceA">"Lalla." Complete Dictionary of Scientific Biography.</ref> He lived in central India, possibly in the [[Lāṭa]] region in modern south [[Gujarat]].<ref>{{Harvtxt|Plofker|2009|p=321}}</ref> Lalla was known as being one of the leading Indian astronomers of the eighth century.<ref name="ReferenceA"/>
Only two of his works are currently thought to be extant.<ref name="Bracher, Katherine">Bracher, Katherine</ref>

His best-known work is the ''Śiṣyadhīvṛddhidatantra'' ("Treatise which expands the intellect of students").  This text is one of the first major Sanskrit astronomical texts known from the period following the 7th-century works of [[Brahmagupta]] and [[Bhāskara I]].<ref name="Bracher, Katherine"/> It generally treats the same astronomical subject matter and demonstrates the same computational techniques as earlier authors, although there are some significant innovations, such that Lalla’s treatise offers a compromise between the rival astronomical schools of his predecessors, [[Āryabhaṭa I]] and Brahmagupta.<ref name="Bracher, Katherine"/> It is within the ''Śiṣyadhīvṛddhidatantra'' that the earliest known description of ''[[perpetual motion]]'' is described.

The other extant work by Lalla is the ''Jyotiṣaratnakośa'' ("Treasury of Jewels"), a treatise on catarchic astrology. This work is one of the earliest known Sanskrit astrological works for determining auspicious and inauspicious times. No edition of this text has ever been published while the known manuscripts are incomplete.<ref name="Bracher, Katherine"/>

In his work, Lalla drew on his predecessors [[Brahmagupta]], and [[Bhāskara I]]. In turn, he influenced later generations of astronomers, including [[Āryabhaṭa II]], [[Śrīpati]], [[Vaṭeśvara]], and [[Bhāskara II]] (who later wrote a commentary on the ''Śiṣyadhīvṛddhidatantra'').<ref>{{Harvtxt|Plofker|2009|p=318}}</ref>

He followed the Āryapakṣa or the school of [[Āryabhaṭa]] (continued by Bhāskara I), but divided the ''mahāyuga'' in the traditional way, following the Brāhmapakṣa school
of [[Brahmagupta]].<ref>{{Harvtxt|Plofker|2009|p=71}}</ref>

== Works ==
* ''Śiṣyadhīvṛddhidatantra'': The most extensive extant exposition of the views of the Āryapaksa school. It contains twenty-two chapters divided into two books:<ref name="ReferenceA"/> 
: I. On the Computation of the Positions of the Planets
# On the mean longitudes of the planets.
# On the true longitudes of the planets.
# On the three problems involving diurnal motion.
# On lunar eclipses.
# On solar eclipses.
# On the syzygies.
# On the heliacal settings and risings of the planets.
# On the shadow of the moon.
# On the lunar crescent.
# On planetary conjunctions.
# On conjunctions of the planets with the stars.
# On the pātas of the sun and moon.
# Conclusion.
: II. On the Sphere
# On graphical representations.
# On the construction of the celestial sphere.
# On the principles of mean motion.
# On the terrestrial sphere.
# On the motions and stations of the planets.
# On geography.
# On erroneous knowledge.
# On instruments.
# On certain (selected) problems"<ref name="ReferenceA"/>
* ''Jyotiṣaratnakośa'': A popular book on astronomy in India<ref name="mb">MacTutor biography</ref>
* A commentary on [[Brahmagupta]]'s ''Khandakhadyaka'', now lost<ref name=mb/>

==Notes==
<references/>

== References ==
* {{MacTutor Biography|id=Lalla}}
* [[K. V. Sarma]]. "Lalla." ''Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures'', ed. [[Helaine Selin]], Dordrecht: Kluwer Academic Publishers, 1997, p.&nbsp;508.
* {{citation | year=2009 | title = Mathematics in India (book) | last=Plofker|first=Kim | publisher=Princeton University Press | isbn=978-0-691-12067-6 | title-link= Mathematics in India (book)}}
* "[http://go.galegroup.com/ps/i.do?id=GALE%7CCX2830902431&v=2.1&u=norm94900&it=r&p=GVRL&sw=w Lalla]." Complete Dictionary of Scientific Biography. Vol. 7. Detroit: Charles Scribner's Sons, 2008. 582-583. Gale Virtual Reference Library. Web. 3 June 2013.
*Bracher, Katherine. [https://web.archive.org/web/20121010024012/http://link.springer.com/book/10.1007/978-0-387-30400-7/page/1 The Biographical Encyclopedia Of Astronomers] [Electronic Resource] / Edited By K. Bracher ... [Et Al.]. n.p.: New York; London : Springer, 2006., 2006. UNIV OF OKLAHOMA LIBRARIES's Catalog. Web. 6 June 2013.
{{Authority control}}

[[Category:8th-century Indian astronomers]]
[[Category:8th-century Indian mathematicians]]
[[Category:720s births]]
[[Category:790 deaths]]
[[Category:Scholars from Gujarat]]