Abul-Hasan Kūshyār ibn Labbān ibn Bashahri Daylami (971–1029), also known as Kūshyār Daylami ( fa, کوشیار دیلمی), was an
Iranian
Iranian may refer to:
* Iran, a sovereign state
* Iranian peoples, the speakers of the Iranian languages. The term Iranic peoples is also used for this term to distinguish the pan ethnic term from Iranian, used for the people of Iran
* Iranian lan ...
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems.
Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change.
History
On ...
,
geographer
A geographer is a physical scientist, social scientist or humanist whose area of study is geography, the study of Earth's natural environment and human society, including how society and nature interacts. The Greek prefix "geo" means "earth" a ...
, and
astronomer
An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...
from
Daylam
Daylam, also known in the plural form Daylaman (and variants such as Dailam, Deylam, and Deilam), was the name of a mountainous region of inland Gilan, Iran. It was so named for its inhabitants, known as the Daylamites.
The Church of the East es ...
, south of the
Caspian Sea
The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central Asia ...
,
Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
.
Career
His main work was probably done about the beginning of the eleventh century, and seems to have taken an important part in the elaboration of
trigonometry
Trigonometry () is a branch of mathematics that studies relationships between side lengths and angles of triangles. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies ...
. For example, he continued the investigations of
Abul Wáfa
Abū al-Wafāʾ Muḥammad ibn Muḥammad ibn Yaḥyā ibn Ismāʿīl ibn al-ʿAbbās al-Būzjānī or Abū al-Wafā Būzhjānī ( fa, ابوالوفا بوزجانی or بوژگانی) (10 June 940 – 15 July 998) was a Persian mathematician ...
, and devoted much space to this in his
zij (or collection of tables) ''az-Zīj al-Jamī wal-Baligh'' ("the comprehensive and mature tables"), which incorporated the improved values of the planetary apogees observed by
al-Battani
Abū ʿAbd Allāh Muḥammad ibn Jābir ibn Sinān al-Raqqī al-Ḥarrānī aṣ-Ṣābiʾ al-Battānī ( ar, محمد بن جابر بن سنان البتاني) ( Latinized as Albategnius, Albategni or Albatenius) (c. 858 – 929) was an astron ...
.
[E. S. Kennedy, ''A Survey of Islamic Astronomical Tables,'' (Transactions of the American Philosophical Society, New Series, 46, 2), Philadelphia, 1956, pp. 3, 34-5.] The tables were translated into Persian before the end of the century. He wrote also an astrological introduction and an arithmetic treatise ''Kitab fi usul hisab al-hind'' (
Principles of Hindu Reckoning
''Principles of Hindu Reckoning'' (''Kitab fi usul hisab al-hind'') is a mathematics book written by the 10th- and 11th-century Persian mathematician Kushyar ibn Labban. It is the second-oldest book extant in Arabic about Hindu arithmetic using Hi ...
, extant in Arabic and Hebrew).
He was the teacher of
Ahmad Nasawi. He is thought to have died in
Baghdad
Baghdad (; ar, بَغْدَاد , ) is the capital of Iraq and the second-largest city in the Arab world after Cairo. It is located on the Tigris near the ruins of the ancient city of Babylon and the Sassanid Persian capital of Ctesiphon. I ...
.
See also
*
List of Iranian scientists
The following is a non-comprehensive list of Iranian scientists, engineers, and scholars who lived from antiquity up until the beginning of the modern age. For the modern era, see List of contemporary Iranian scientists, scholars, and engineer ...
*
zij
References
Sources
* H. Suter: Mathematiker und Astronomen der Araber (83, 235, 1900; 168, 1902).
* M Levey and M Petruck (trs.), Kushyar ibn Labban, Principles of Hindu reckoning (Madison, 1965).
External links
*
PDF version
971 births
1029 deaths
10th-century Iranian mathematicians
10th-century Iranian astronomers
11th-century Iranian astronomers
People from Gilan Province
{{Asia-mathematician-stub