Yaʿqūb ibn Ṭāriq

Yaʿqūb ibn Ṭāriq (يعقوب بن طارق; died c. 796 AD) was an 8th-century Persian astronomer and mathematician who lived in Baghdad.

Works

Works ascribed to Yaʿqūb ibn Ṭāriq include:^[1]

• Zīj maḥlūl fī al‐Sindhind li‐daraja daraja (زيج محلول في السندهند لدرجة درجة, "Astronomical tables in the Sindhind resolved for each degree"),
• Tarkīb al‐aflāk (تركیب الأفلاك, "Arrangement of the orbs"),
• Kitāb al‐ʿilal (كتاب العلل, "Rationales"),
• Taqṭīʿ kardajāt al‐jayb (تقطيع كردجات الجيب, "Distribution of the kardajas of the sine"), and
• Mā irtafaʿa min qaws niṣf al‐nahār (ما إرتفع من قوس نصف النهار, "Elevation along the arc of the meridian").

An astrological work called Al‐maqālāt (المقالات, "The Chapters") is also ascribed to him by an unreliable source.^[1]

The Zīj, written around 770, was based on a Sanskrit work,^[1] thought to be similar to the Brāhmasphuṭasiddhānta.^[2] This work was brought to the court of al-Mansūr from Sindh,^[2] reportedly by an Sindhi astronomer named Kankah.^[3]

The Tarkīb al‐aflāk dealt with cosmography, that is, the placement and sizes of the heavenly bodies.^[1] Its estimates of the sizes and distances of the heavenly bodies were tabulated in al-Bīrūnī's work on India; according to him, Yaʿqūb ibn Ṭāriq gave the radius of the Earth as 1,050 farsakhs, the diameter of the Moon and Mercury as 5,000 farsakhs (4.8 Earth radii), and the diameter of the other heavenly bodies (Venus, the Sun, Mars, Jupiter, and Saturn) as 20,000 farsakhs (19.0 Earth radii.)^[4]

Notes

Further reading

• Hogendijk, Jan P. (1988). "New Light on the Lunar Crescent Visibility Table of Yaʿqūb ibn Ṭāriq". Journal of Near Eastern Studies. 47 (2): 95. doi:10.1086/373260. JSTOR 544381. 
• Kennedy, E. S. (1956). "A Survey of Islamic Astronomical Tables". Transactions of the American Philosophical Society, New Series. 46 (2): 123–177. doi:10.2307/1005726. JSTOR 1005726. 
• Kennedy, E. S. (1968). "The Lunar Visibility Theory of Yaʿqūb Ibn Ṭāriq". Journal of Near Eastern Studies. 27 (2): 126. doi:10.1086/371945. JSTOR 543759. 
• Pingree, David (1968). "The Fragments of the Works of Yaʿqūb Ibn Ṭāriq". Journal of Near Eastern Studies. 27 (2): 97. doi:10.1086/371944. JSTOR 543758. 
• Pingree, David (1976). "Yaʿqūb ibn Ṭāriq". In Gillispie, Charles Coulston. Dictionary of Scientific Biography. 14. New York: Charles Scribner's Sons. p. 546. ISBN 0-684-16962-2. 
• Plofker, Kim (2007). "Yaʿqūb ibn Ṭāriq". In Thomas Hockey; et al. The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 1250–1. ISBN 978-0-387-31022-0.  (PDF version)
• Sezgin, Fuat (1978). Geschichte des arabischen Schrifttums. Vol. 6, Astronomie, pp. 124–127. Leiden: E. J. Brill.
• Steinschneider, Moritz (1870). "Zur Geschichte der Uebersetzungen aus dem Indischen in's Arabische und ihres Einflusses aus die arabische Literatur". Zeitschrift der Deutschen Morgenländischen Gesellschaft. 24: 332. 
• Suter, Heinrich (1900). Die Mathematiker und Astronomer der Araber. p. 4. 

Mathematics in medieval Islam
Mathematicians (Works)	9th century 'Abd al-Hamīd ibn Turk Sind ibn Ali Al-Abbās ibn Said al-Jawharī Al-Ḥajjāj ibn Yūsuf ibn Maṭar Al-Kindi De Gradibus Al-Mahani Banū Mūsā Hunayn ibn Ishaq al-Khwārizmī The Compendious Book on Calculation by Completion and Balancing ibn Qurra Na'im ibn Musa Sahl ibn Bishr Habash al-Hasib al-Marwazi 10th century Abd al-Rahman al-Sufi Book of Fixed Stars al-Būzjānī Abū Ja'far al-Khāzin Abū Kāmil Shujāʿ ibn Aslam Abu'l-Hasan al-Uqlidisi Abu-Mahmud Khojandi Ahmad ibn Yusuf Al-Nayrizi Al-Saghani Brethren of Purity Ibn Sahl Ibn Yunus Ibrahim ibn Sinan Muhammad ibn Jābir al-Harrānī al-Battānī Sinan ibn Thabit Al-Isfahani Nazif ibn Yumn Abū Sahl al-Qūhī 11th century Abū Ishāq Ibrāhīm al-Zarqālī Abu Nasr Mansur Abū Rayḥān al-Bīrūnī Ibn al-Haytham / Alhazen Book of Optics Ibn Muʿādh al-Jayyānī Al-Karaji Al-Sijzi Alī ibn Ahmad al-Nasawī Avicenna The Book of Healing Ibn Tahir al-Baghdadi Kushyar ibn Labban Yusuf al-Mu'taman ibn Hud 12th century Al-Khazini Ibn Yahyā al-Maghribī al-Samaw'al Omar Khayyám Jabir ibn Aflah Abu Bakr al-Hassar 13th century Muhyi al-Dīn al-Maghribī Nasīr al-Dīn al-Tūsī Zij-i Ilkhani Shams al-Dīn al-Samarqandī Sharaf al-Dīn al-Tūsī Ibn al‐Ha'im al‐Ishbili Ibn Abi al-Shukr 14th century Yaʿīsh ibn Ibrāhīm al-Umawī Ibn al-Banna' al-Marrakushi Ibn al-Shatir Kamāl al-Dīn Fārisī Al-Khalili Qotb al-Din Shirazi Ahmad al-Qalqashandi 15th century Abū al-Ḥasan ibn ʿAlī al-Qalaṣādī Ali Qushji Jamshīd al-Kāshī Qāḍī Zāda al-Rūmī Ulugh Beg Ibn al-Majdi 16th century Al-Birjandi Muhammad Baqir Yazdi Taqi al-Din Ibn Hamza al-Maghribi Ibn Ghazi al-Miknasi
Other treatises	Almanac Encyclopedia of the Brethren of Purity Tables of Toledo Tabula Rogeriana Zij Zij-i-Sultani
Concepts	Alhazen's problem Islamic geometric patterns
Centers	Al-Azhar University Al-Mustansiriya University House of Knowledge House of Wisdom Istanbul observatory of Taqi al-Din Madrasah Maktab Maragheh observatory University of Al-Karaouine
Influences	Babylonian mathematics Greek mathematics Indian mathematics
Influenced	Byzantine mathematics European mathematics Indian mathematics