Al-Hassar or Abu Bakr Muhammad ibn Abdallah ibn Ayyash al-Hassar ( ar, أبو بكر محمد ابن عياش الحصَار) was a 12th-century Moroccan

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

. He is the author of two books ''Kitab al-bayan wat-tadhkar'' (Book of Demonstration and Memorization), a manual of calculation and ''Kitab al-kamil fi sinaat al-adad'' (Complete Book on the Art of Numbers), on the breakdown of numbers. The first book is lost and only a part of the second book remains. Al-Hassar developed the modern symbolic

mathematical notation Mathematical notation consists of using symbols for representing operations, unspecified numbers, relations and any other mathematical objects, and assembling them into expressions and formulas. Mathematical notation is widely used in mathem ...

for

fractions A fraction (from la, fractus, "broken") represents a part of a whole or, more generally, any number of equal parts. When spoken in everyday English, a fraction describes how many parts of a certain size there are, for example, one-half, eight ...

, where the

numerator A fraction (from la, fractus, "broken") represents a part of a whole or, more generally, any number of equal parts. When spoken in everyday English, a fraction describes how many parts of a certain size there are, for example, one-half, eight ...

and

denominator A fraction (from la, fractus, "broken") represents a part of a whole or, more generally, any number of equal parts. When spoken in everyday English, a fraction describes how many parts of a certain size there are, for example, one-half, eight ...

are separated by a horizontal bar. This same fractional notation appeared soon after in the work of

Fibonacci Fibonacci (; also , ; – ), also known as Leonardo Bonacci, Leonardo of Pisa, or Leonardo Bigollo Pisano ('Leonardo the Traveller from Pisa'), was an Italian mathematician from the Republic of Pisa, considered to be "the most talented Wester ...

in the 13th century.

References

*Suter, Heinrich, ''Beitraege zur Geschichte der Mathematik und Astronomie im Islam. Nachdruck seiner Schriften aus den Jahren 1892-1922.'' ontributions to the history of mathematics and astronomy in Islam. Reprint of his works from the years 1892-1922 Hrsg. von Fuat Sezgin. Baende 1 und 2. d. by Fuat Sezgin. Volumes 1 and 2Veroeffentlichungen des Institutes fuer Geschichte der Arabisch-Islamischen Wissenschaften. Reihe B: Nachdrucke, Abteilung Mathematik, Bd. 1 ublications of the Institute for the History of Arabic-Islamic Sciences. Series B: Section Mathematics, vol. 1Frankfurt am Main: Institut fuer Geschichte der Arabisch- Islamischen Wissenschaften an der Johann Wolfgang Goethe-Universitaet, 1986. Band I: xiii, 761 S.; Band II: x, 724 S. *

External links

*Prof. Paul Kunitzsch, ''Al-Hassâr's Kitâb al-Bayân and the Transmission of the Hindu-Arabic Numerals'

retrieved 01-09-2010) *Manuscript of ''Kitâb al-bayân wa-l-tadhkâr'', online by Library of the

University of Pennsylvania The University of Pennsylvania (also known as Penn or UPenn) is a private research university in Philadelphia. It is the fourth-oldest institution of higher education in the United States and is ranked among the highest-regarded universitie ...

, Philadelphi

(retrieved 01-09-2010) {{DEFAULTSORT:Hassar, Abubakr Medieval Moroccan mathematicians 12th-century mathematicians Moroccan writers Year of death unknown Year of birth missing 12th-century Moroccan writers

References

Further reading

External links