Habash al-Hasib al-Marwazi
Habash al - Hasib al - Marwazi (Arabic حبش الحاسب المروزي, DMG Habas al - Hasib al - Marwazi, Ahmad ibn Abdallah al - actually Marwazi / أحمد بن عبد الله المروزي / Aḥmad b. ʿ Abd Allāh al - Marwazi (* in Merv probably before 796; † after 869 probably in Samarra ) was a Persian mathematician, astronomer and geographer.
Life
He looked in under the caliph al - Ma ʾ mun ( 830 Founder of the House of Wisdom in Baghdad ) and its successor al - Mu'tasim bi- ' llāh, first in Baghdad and possibly Damascus, later in Samarra ( the 838 capital of the Abbasid dynasty ). The exact life data are not known, but he died after Ibn al - Nadim (d. 995 ) with more than 100 years. The earliest news about him has been handed down by the Egyptian astronomer Ibn Yunus, who reported in Baghdad by an observation of al - Marwazi 829/830. Habash al - Hasib means Habash, the computer (meaning theoretical astronomy).
He wrote two astronomical handbooks ( Zīdsch ) still show no Ptolemaic influence (one is in the Indian Sindhind tradition and by Muhammad ibn Ibrahim al - Khwarizmi and al- Fazarhi ) and therefore probably arose prior to the time around 830, when the Caliph in Baghdad, a group of astronomers called ( Ashab al - Mumtahan ), which should verify the parameters of the Ptolemaic system. Al- Marwazi belonged to her although not directly by its own account, but presented in this context observations and presented the results after the death of al - Mamun in a third, Ptolemaic embossed astronomical handbook represents the only preserved by him Zīdsch. From the latest there recorded observation (September 15, 869 ) results that he died after 869 ( and his major work completed and only then ). Assuming that he was at that time not more than 75 years, he was born before 796. Its life span is thus approximately equal to that of al -Kindi and Albumasar. The investigations of the school of Baghdad sat down in the Islamic world the ancient Ptolemaic astronomical system of the Persian and Indian through. It is also the earliest preserved astronomical separate manual from the Islamic world following the Ptolemaic system. He improved the parameters of Ptolemy and led their own calculation methods a (probably influenced by Indian sources ). Of particular importance are his trigonometric tables. He was the first to tangent and cotangent on panels that were defined by the Arabs on the length of the shadow of sundials ( with a horizontal bar on a vertical wall or a vertical bar on the plane). He also calculated accurate sine tables ( at a distance of 1 degree to three decimal places ).
Manuscripts of his main work in Istanbul and Berlin. In addition, smaller works are preserved:
- The book of the body and distances, in which he describes, among other things, an expedition to determine the radius of the earth .. There are also made information about diameters and distances of the sun and moon.
- A book about the construction of a melon -shaped astrolabe.
- A manuscript on an original instrument to determine the sidereal time.
- Works on the spherical astrolabe, the armillary sphere and celestial globe.
He gave a graphic design determining the direction to Mecca ( analemma construction ), received in a letter from al -Biruni and the main plant ( Zīdsch ) of al - Marwazi.