Muhammad ibn Musa al-Khwarizmi
The Father of Algebra
Muhammad ibn Mūsā al-Khwārizmī was a Persian polymath who produced works in mathematics, astronomy, and geography. Around 820 CE he was appointed as the astronomer and head of the library of the House of Wisdom in Baghdad. The term algebra itself comes from the title of his book (specifically the word al-jabr meaning "completion" or "rejoining"). His name gave rise to the terms algorism and algorithm.
He was born into a Persian family and Ibn al-Nadim gives his birthplace as Khwarezm in Greater Khorasan (modern Khiva, Xorazm Region, Uzbekistan). Al-Khwārizmī accomplished most of his work in the period between 813 and 833. After the Muslim conquest of Persia, Baghdad became the centre of scientific studies and trade. He worked in Baghdad as a scholar at the House of Wisdom established by Caliph al-Ma’mūn, where he studied the sciences and mathematics, which included the translation of Greek and Sanskrit scientific manuscripts.
Contributions
Algebra
Al-Khwarizmi's popularizing treatise on algebra (The Compendious Book on Calculation by Completion and Balancing, c. 813–833 CE) presented the first systematic solution of linear and quadratic equations. Because he was the first to treat algebra as an independent discipline and introduced the methods of "reduction" and "balancing", he has been described as the father or founder of algebra.
Arithmetic
In the 12th century, Latin translations of his textbook on arithmetic (Algorithmo de Numero Indorum) which codified the various Indian numerals, introduced the decimal positional number system to the Western world. The Compendious Book on Calculation by Completion and Balancing, translated into Latin by Robert of Chester in 1145, was used until the sixteenth century as the principal mathematical text-book of European universities.
Astronomy
Al-Khwārizmī produced a set of astronomical tables and wrote about calendaric works, as well as the astrolabe and the sundial. His book, Zīj al-Sindhind (astronomical tables of Siddhanta), consist of approximately 37 chapters on calendrical and astronomical calculations and 116 tables with calendrical, astronomical and astrological data, as well as a table of sine values. The work contains tables for the movements of the sun, the moon and the five planets known at the time. This work marked the turning point in Islamic astronomy.
Trigonometry
He also made important contributions to trigonometry, producing accurate sine and cosine tables, and the first table of tangents. Al-Khwārizmī's Zīj al-Sindhind contained tables for the trigonometric functions of sines and cosine. A related treatise on spherical trigonometry is also attributed to him.
Geography
In addition to his best-known works, he revised Ptolemy's Geography, listing the longitudes and latitudes of various cities and localities. Al-Khwārizmī's third major work is his Kitāb Sūrat al-Ard (Book of the Description of the Earth), also known as his Geography, which was finished in 833. It is a major reworking of Ptolemy's 2nd-century Geography, consisting of a list of 2402 coordinates of cities and other geographical features following a general introduction.
"When I consider what people generally want in calculating, I found that it always is a number."