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 Hametus, was a
Muslim
Muslims ( ar, المسلمون, , ) are people who adhere to Islam, a monotheistic religion belonging to the Abrahamic tradition. They consider the Quran, the foundational religious text of Islam, to be the verbatim word of the God of Abrah ...
Arab mathematician, like his father
Yusuf ibn Ibrahim ( ar, يوسف بن ابراهيم الصدَيق البغدادي ).
Life
Ahmad ibn Yusuf was born in
Baghdad and moved with his father to
Damascus
)), is an adjective which means "spacious".
, motto =
, image_flag = Flag of Damascus.svg
, image_seal = Emblem of Damascus.svg
, seal_type = Seal
, map_caption =
, ...
in 839. He later moved to
Cairo, 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
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
,
Astronomy and
Medicine, produced astronomical tables and was a member of a group of scholars. He achieved an important role in
Egypt, which was caused by Egypt's relative independence from the
Abbasid Caliph
The Abbasid caliphs were the holders of the Islamic title of caliph who were members of the Abbasid dynasty, a branch of the Quraysh tribe descended from the uncle of the Islamic prophet Muhammad, Al-Abbas ibn Abd al-Muttalib.
The family came t ...
.
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 and
proportion. This was translated to Latin by
Gherard of Cremona and was a commentary of
Euclid's ''Elements''. This book influenced early European mathematicians such as
Fibonacci. Further, in ''On similar arcs'', he commented on
Ptolemy's ''Karpos'' (or ''
Centiloquium''); 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
An astrolabe ( grc, ἀστρολάβος ; ar, ٱلأَسْطُرلاب ; persian, ستارهیاب ) is an ancient astronomical instrument that was a handheld model of the universe. Its various functions also make it an elaborate inclin ...
. 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
Thomas Bradwardine (c. 1300 – 26 August 1349) was an English cleric, scholar, mathematician, physicist, courtier and, very briefly, Archbishop of Canterbury. As a celebrated scholastic philosopher and doctor of theology, he is often call ...
,
Jordanus de Nemore and
Luca Pacioli
Fra Luca Bartolomeo de Pacioli (sometimes ''Paccioli'' or ''Paciolo''; 1447 – 19 June 1517) was an Italian mathematician, Franciscan friar, collaborator with Leonardo da Vinci, and an early contributor to the field now known as accounting ...
.
See also
*
List of Arab scientists and scholars
Notes
*
* H. L. L. Busard and P. S. van Koningsveld, ''Der "Liber de arcubus similibus" des Ahmad ibn Jusuf'',
Annals of science
''Annals of Science'' is a peer-reviewed academic journal covering the history of science and technology. It is published by Taylor & Francis and was established in 1936. The founding editor-in-chief was the Canadian historian of science Harcourt ...
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