Abū al-Ḥassan, Aḥmad Ibn Ibrāhīm, al-Uqlīdisī (, ) was a
Muslim
Muslims () are people who adhere to Islam, a Monotheism, monotheistic religion belonging to the Abrahamic religions, Abrahamic tradition. They consider the Quran, the foundational religious text of Islam, to be the verbatim word of the God ...
Arab
Arabs (, , ; , , ) are an ethnic group mainly inhabiting the Arab world in West Asia and North Africa. A significant Arab diaspora is present in various parts of the world.
Arabs have been in the Fertile Crescent for thousands of years ...
mathematician of the Islamic Golden Age, possibly from
Damascus
Damascus ( , ; ) is the capital and List of largest cities in the Levant region by population, largest city of Syria. It is the oldest capital in the world and, according to some, the fourth Holiest sites in Islam, holiest city in Islam. Kno ...
, who wrote the earliest surviving book on the use of
decimal
The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers (''decimal fractions'') of th ...
fractions with
Hindu–Arabic numerals, ''Kitāb al-Fuṣūl fī al-Ḥisāb al-Hindī'' (''The Book of Chapters on Hindu Arithmetic''), in
Arabic
Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...
in 952. The book is well preserved in a single 12th century manuscript,
[MS 802 at Yeni Cami Library, ]Istanbul
Istanbul is the List of largest cities and towns in Turkey, largest city in Turkey, constituting the country's economic, cultural, and historical heart. With Demographics of Istanbul, a population over , it is home to 18% of the Demographics ...
, written in 582 AH (1186 AD) but other than the author's name, original year of publication (341
AH, 952/3 AD) and the place (
Damascus
Damascus ( , ; ) is the capital and List of largest cities in the Levant region by population, largest city of Syria. It is the oldest capital in the world and, according to some, the fourth Holiest sites in Islam, holiest city in Islam. Kno ...
) we know nothing else about the author: after an extensive survey of extant reference material, mathematical historian
Ahmad Salīm Saʿīdān, who discovered the manuscript in 1960, could find no other mention of him. His nickname ''al-Uqlīdisī'' ("the Euclidean") was commonly given to people who sold manuscript copies of
Euclid's ''Elements''.
In the introductory remarks to his ''Arithmetic'', Al-Uqlīdisī claims that he traveled to confer with every arithmetic expert he knew of, and read every previous book he could find, and comprehensively synthesized this previous work while adding his own ideas. The ''Arithmetic'' describes the main calculation methods of
medieval Islamic arithmetic, including finger reckoning, the Greco-Babylonian
sexagesimal
Sexagesimal, also known as base 60, is a numeral system with 60 (number), sixty as its radix, base. It originated with the ancient Sumerians in the 3rd millennium BC, was passed down to the ancient Babylonians, and is still used—in a modified fo ...
system commonly used for astronomy, calculations with fractions, and positional decimal calculations using the Hindu–Arabic system performed using the dust board and stylus. It is especially notable for its treatment of
decimal fractions, and for showing how to calculate using pen and paper rather than an erasable dust board.
While the
Persian mathematician
Jamshīd al-Kāshī
Ghiyāth al-Dīn Jamshīd Masʿūd al-Kāshī (or al-Kāshānī) ( ''Ghiyās-ud-dīn Jamshīd Kāshānī'') (c. 1380 Kashan, Iran – 22 June 1429 Samarkand, Transoxiana) was a Persian astronomer and mathematician during the reign of Tamerlane.
...
claimed to have discovered decimal fractions himself in the 15th century, J. Lennart Berggren notes that he was mistaken, as decimal fractions were first used five centuries before him by al-Uqlidisi as early as the 10th century.
A. S. Saidan who studied al-Uqlidisi's mathematical treatise in detail wrote:
The most remarkable idea in this work is that of decimal fraction. Al-Uqlidisi uses decimal fractions as such, appreciates the importance of a decimal sign, and suggests a good one. Not al-Kashi (d. 1436/7) who treated decimal fractions in his "Miftah al-Hisab", but al-Uqlidisi, who lived five centuries earlier, is the first Muslim mathematician so far known to write about decimal fractions.
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10th-century Arab people
10th-century mathematicians
Medieval Syrian mathematicians
People from Damascus
10th-century Syrian people
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