Al - Khwarizmi

Abu Ja'far Muhammad ibn Musa Al - Khwarizmi

Born: about 780 in Khwarazm (now Kharazm province in Uzbekistan.)

Al'Khwarizmi was an Islamic mathematician who wrote on Hindu - Arabic numerals andwas among the first to use zero as a place holder in positional base notation. The word algorithm derives from his name. His algebra treatise Hisab al - jabr w'al -muqabala gives us the wordalgebra and can be considered as the first book to be written on algebra.

We know few details of Abu Ja'far Muhammad ibn Musa al - Khwarizmi's life. One unfortunate effect of this lack of knowledge seems to be the temptation to make guesses based on very little evidence. But the name al - Khwarizmi may indicate that he came from Khwarizm south of the Aral Sea in Central Asia. The algebra treatise Hisab al - jabr w'al - muqabala was the most famous and important of all of al - Khwarizmi's works. It is the title of this text that gives us the word "algebra" and it is the first book to be written on algebra. The book was the written in Baghdad, where al - Khwarizmi worked under the patronage of Caliph Al - Mamun and he dedicated two of his texts to the Caliph. Al - Mamun was a great patron of learning and founded an academy called the House of Wisdom where Greek philosophical and scientific works were translated. He also built up a library of manuscripts, the first major library to be set up since that at Alexandria, collecting important works from Byzantium. In addition to the House of Wisdom, al - Mamun set up observatories in which Muslim astronomers could build on the knowledge acquired by earlier peoples. Al - Khwarizmi and his colleagues the Banu Musa were scholars at the House of Wisdom in Baghdad. Their tasks there involved the translation of Greekscientific manuscripts and they also studied, and wrote on, algebra, geometryand astronomy. These were his treatise on algebra and his treatise on astronomy.

 

Al - Khwarizmi also wrote a treatise on Hindu-Arabic numerals. The Arabic text is lost but a Latin translation, Algoritmi de numero Indorum in English Al - Khwarizmi on the Hindu Art of Reckoning gave rise to the word algorithm deriving from his name in the title. Unfortunately the Latin translation (translated into English in 19) is known to be much changed from al - Khwarizmi's original text (of which even the title is unknown). The work describes the Hindu place - value system of numerals based on 1, 2, 3, 4, 5, 6, 7, 8, 9, and 0. The first use of zero as a place holder in positional base notation was probably due to al - Khwarizmi in this work. Methods for arithmetical calculation are given, and a method to find square roots is known to have been in the Arabic original although it is missing from the Latin version.

Al - Khwarizmi wrote a major work on geography which give latitudes and longitudes for 2402 localities as a basis for a world map. The book, which is based on Ptolemy's Geography, lists with latitudes and longitudes, cities, mountains, seas, islands, geographicalregions, and rivers. The manuscript does include maps which on the whole are more accurate than those of Ptolemy. In particular it is clear that where more local knowledge was available to al - Khwarizmi such as the regions of Islam, Africa and the Far East then his work is considerably more accurate than that of Ptolemy, but for Europe al - Khwarizmi seems to have used Ptolemy's data. A number of minor works were written by al - Khwarizmi on topics such as the astrolabe, on which he wrote two works, on the sundial, and on the Jewish calendar. He also wrote a political history containing horoscopes of prominent persons.