Ahmad ibn Yusuf

Abu Ja'far Ahmad ibn Yusuf ibn Ibrahim ibn Tammam al-Siddiq Al-Baghdadi (Arabic: 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 Arab mathematician, like his father Yusuf ibn Ibrahim (Arabic: يوسف بن ابراهيم الصدَيق البغدادي).

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Life

Ahmad ibn Yusuf was born in Baghdad and moved with his father to Damascus 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, 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.

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.^[1] 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 and Luca Pacioli.

Notes

^ 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

Schrader, Dorothy (1970). "Aḥmad Ibn Yūsef". Dictionary of Scientific Biography. Vol. 1. New York: Charles Scribner's Sons. pp. 82–83. ISBN 0-684-10114-9.
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

O'Connor, John J.; Robertson, Edmund F., "Ahmad ibn Yusuf", MacTutor History of Mathematics Archive, University of St Andrews
Schrader, Dorothy V. (2008) [1970–80]. "Aḥmad Ibn Yūsuf". Complete Dictionary of Scientific Biography. Encyclopedia.com.

Mathematics in the medieval Islamic world

Mathematicians

9th century	'Abd al-Hamīd ibn Turk Sanad ibn Ali al-Jawharī Al-Ḥajjāj ibn Yūsuf Al-Kindi Qusta ibn Luqa Al-Mahani al-Dinawari Banū Mūsā Hunayn ibn Ishaq Al-Khwarizmi Yusuf al-Khuri Ishaq ibn Hunayn Na'im ibn Musa Thābit ibn Qurra al-Marwazi Abu Said Gorgani
10th century	Abu al-Wafa al-Khazin Al-Qabisi Abu Kamil Ahmad ibn Yusuf Aṣ-Ṣaidanānī Sinān ibn al-Fatḥ al-Khojandi Al-Nayrizi Al-Saghani Brethren of Purity Ibn Sahl Ibn Yunus al-Uqlidisi Al-Battani Sinan ibn Thabit Ibrahim ibn Sinan Al-Isfahani Nazif ibn Yumn al-Qūhī Abu al-Jud Al-Sijzi Al-Karaji al-Majriti al-Jabali
11th century	Abu Nasr Mansur Alhazen Kushyar Gilani Al-Biruni Ibn al-Samh Abu Mansur al-Baghdadi Avicenna al-Jayyānī al-Nasawī al-Zarqālī ibn Hud Al-Isfizari Omar Khayyam Muhammad al-Baghdadi
12th century	Jabir ibn Aflah Al-Kharaqī Al-Khazini Al-Samawal al-Maghribi al-Hassar Sharaf al-Din al-Tusi Ibn al-Yasamin
13th century	Ibn al‐Ha'im al‐Ishbili Ahmad al-Buni Ibn Munim Alam al-Din al-Hanafi Ibn Adlan al-Urdi Nasir al-Din al-Tusi al-Abhari Muhyi al-Din al-Maghribi al-Hasan al-Marrakushi Qutb al-Din al-Shirazi Shams al-Din al-Samarqandi Ibn al-Banna' Kamāl al-Dīn al-Fārisī
14th century	Nizam al-Din al-Nisapuri Ibn al-Shatir Ibn al-Durayhim Al-Khalili al-Umawi
15th century	Ibn al-Majdi al-Rūmī al-Kāshī Ulugh Beg Ali Qushji al-Wafa'i al-Qalaṣādī Sibt al-Maridini Ibn Ghazi al-Miknasi
16th century	Al-Birjandi Muhammad Baqir Yazdi Taqi ad-Din Ibn Hamza al-Maghribi Ahmad Ibn al-Qadi