Abu Ja'far Ahmad ibn Yusuf ibn Ibrahim ibn Tammam al-Siddiq Al-Baghdadi ( ar, أبو جعفر أحمد بن يوسف بن ابراهيم بن تمام الصديق البغدادي; 835–912), known in the West by his
Latinized name
Latinisation (or Latinization) of names, also known as onomastic Latinisation, is the practice of rendering a ''non''-Latin name in a Latin style. It is commonly found with historical proper names, including personal names and toponyms, and in ...
Hametus, was a
Muslim Arab
The Arabs (singular: Arab; singular ar, عَرَبِيٌّ, DIN 31635: , , plural ar, عَرَب, DIN 31635: , Arabic pronunciation: ), also known as the Arab people, are an ethnic group mainly inhabiting the Arab world in Western Asia, ...
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 ...
, like his father
Yusuf ibn Ibrahim ( ar, يوسف بن ابراهيم الصدَيق البغدادي ).
Life
Ahmad ibn Yusuf was born 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 ...
and moved with his father to
Damascus in 839. He later moved to
Cairo
Cairo ( ; ar, القاهرة, al-Qāhirah, ) is the Capital city, capital of Egypt and its largest city, home to 10 million people. It is also part of the List of urban agglomerations in Africa, largest urban agglomeration in Africa, List of ...
, but the exact date is unknown: since he was also known as ''al-Misri'', which means ''the Egyptian'', this probably happened at an early age. Eventually, he also died in Cairo. He probably grew up in a strongly intellectual environment: his father worked on
Mathematics,
Astronomy
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
and
Medicine
Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pr ...
, produced astronomical tables and was a member of a group of scholars. He achieved an important role in
Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Medit ...
, which was caused by Egypt's relative independence from the
Abbasid Caliph.
Work
In some of the works attributed to Ahmad, it is not clear if the text came from him, his father, or whether they wrote together. It is clear, however, that he worked on a book on
ratio
In mathematics, a ratio shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...
and
proportion. This was translated to Latin by
Gherard of Cremona
Gerard of Cremona (Latin: ''Gerardus Cremonensis''; c. 1114 – 1187) was an Italian translator of scientific books from Arabic into Latin. He worked in Toledo, Kingdom of Castile and obtained the Arabic books in the libraries at Toledo. Some of ...
and was a commentary of
Euclid
Euclid (; grc-gre, Εὐκλείδης; BC) was an ancient Greek mathematician active as a geometer and logician. Considered the "father of geometry", he is chiefly known for the '' Elements'' treatise, which established the foundations of ...
's ''Elements''. This book influenced early European mathematicians such as
Fibonacci
Fibonacci (; also , ; – ), also known as Leonardo Bonacci, Leonardo of Pisa, or Leonardo Bigollo Pisano ('Leonardo the Traveller from Pisa'), was an Italian mathematician from the Republic of Pisa, considered to be "the most talented Wester ...
. Further, in ''On similar arcs'', he commented on
Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance ...
's ''Karpos'' (or ''
Centiloquium
The ''Centiloquium'' (= "one hundred sayings"), also called ''Ptolemy's Centiloquium'', is a collection of one hundred aphorisms about astrology and astrological rules. It is first recorded at the start of the tenth century CE, when a commentary ...
''); many scholars believe that ibn Yusuf was in fact the true author of that work.
[Richard Lemay, Origin and success of the ''Kitab Thamara'' of Abu Ja'far Ahmad ibn Yusuf, in ''Proceedings of the 1st International Symposium for the History of Arabic Science, University of Aleppo (1976)'', Aleppo 1978] He also wrote a book on the
astrolabe. He invented methods to solve tax problems that were later presented in Fibonacci's ''Liber Abaci''. He was also quoted by mathematicians such as
Thomas Bradwardine,
Jordanus de Nemore
Jordanus de Nemore (fl. 13th century), also known as Jordanus Nemorarius and Giordano of Nemi, was a thirteenth-century European mathematician and scientist. The literal translation of Jordanus de Nemore (Giordano of Nemi) would indicate that he w ...
and
Luca Pacioli.
See also
*
List of Arab scientists and scholars
This is a list of Arab scientists and scholars from the Muslim World, including Al-Andalus (Spain), who lived from antiquity up until the beginning of the modern age, consisting primarily of scholars during the Middle Ages. For a list of cont ...
Notes
*
* H. L. L. Busard and P. S. van Koningsveld, ''Der "Liber de arcubus similibus" des Ahmad ibn Jusuf'',
Annals of science 30 (1973), 381–406.
* M Steinschneider, Yusuf ben Ibrahim und Ahmad ibn Yusuf, Bibliotheca mathematic (1888), 49–117.
External links
*
*
{{DEFAULTSORT:Ahmad ibn Yusuf
Astronomers from the Abbasid Caliphate
People from Baghdad
9th-century mathematicians
10th-century mathematicians
835 births
912 deaths
9th-century Arabs
10th-century Arabs
Mathematicians from the Abbasid Caliphate
10th-century astronomers
10th-century people from the Abbasid Caliphate