Algorism is the technique of performing basicarithmetic by writing numbers inplace value form and applying a set of memorized rules andfacts to the digits. One who practices algorism is known as analgorist. Thispositional notation system has largely superseded earlier calculation systems that used a different set of symbols for each numericalmagnitude, such asRoman numerals, and in some cases required a device such as anabacus.
The wordalgorism comes from the nameAl-Khwārizmī (c. 780–850), aPersian[2][3]mathematician,astronomer,geographer andscholar in theHouse of Wisdom inBaghdad, whose name means "the native ofKhwarezm", which is now in modern-dayUzbekistan.[4][5][6] He wrote a treatise in Arabic language in the 9th century, which was translated intoLatin in the 12th century under the titleAlgoritmi de numero Indorum. This title means "Algoritmi on the numbers of the Indians", where "Algoritmi" was the translator's Latinization of Al-Khwarizmi's name.[7] Al-Khwarizmi was the most widely read mathematician in Europe in the late Middle Ages, primarily through his other book, theAlgebra.[8] In late medieval Latin,algorismus, the corruption of his name, simply meant the "decimal number system" that is still the meaning of modern English algorism. During the 17th century, the French form for the word – but not its meaning – was changed toalgorithm, following the model of the wordlogarithm, this form alluding to the ancient Greekarithmos = number. English adopted the French very soon afterwards, but it wasn't until the late 19th century that "algorithm" took on the meaning that it has in modern English.[9] In English, it was first used about 1230 and then by Chaucer in 1391.[10] Another early use of the word is from 1240, in a manual titledCarmen de Algorismo composed byAlexandre de Villedieu. It begins thus:
Haec algorismus ars praesens dicitur, in qua / Talibus Indorum fruimur bis quinque figuris.
which translates as:
This present art, in which we use those twice five Indian figures, is called algorismus.
The wordalgorithm also derives fromalgorism, a generalization of the meaning to any set of rules specifying a computational procedure. Occasionallyalgorism is also used in this generalized meaning, especially in older texts.
Starting with theintegerarithmetic developed in India usingbase 10 notation,Al-Khwārizmī along with othermathematicians in medieval Islam, documented new arithmetic methods and made many other contributions to decimal arithmetic (see the articles linked below). These included the concept of the decimal fractions as an extension of the notation, which in turn led to the notion of thedecimal point. This system was popularized in Europe by Leonardo of Pisa, now known asFibonacci.[11]
