Al-Hassar or Abu Bakr Muhammad ibn Abdallah ibn Ayyash al-Hassar () 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, mathematical structure, structure, space, Mathematica ...
. 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 glossary of mathematical symbols, symbols for representing operation (mathematics), operations, unspecified numbers, relation (mathematics), relations, and any other mathematical objects and assembling ...
for
fractions
A fraction (from , "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-fifths, thre ...
, where the
numerator
A fraction (from , "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-fifths, thre ...
and
denominator
A fraction (from , "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-fifths, thre ...
are separated by a horizontal bar. This same fractional notation appeared soon after in the work of
Fibonacci
Leonardo Bonacci ( – ), commonly known as Fibonacci, was an Italians, Italian mathematician from the Republic of Pisa, considered to be "the most talented Western mathematician of the Middle Ages".
The name he is commonly called, ''Fibonacci ...
in the 13th century.
References
Further reading
*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 (Penn or UPenn) is a Private university, private Ivy League research university in Philadelphia, Pennsylvania, United States. One of nine colonial colleges, it was chartered in 1755 through the efforts of f ...
, Philadelphi
(retrieved 01-09-2010)
{{DEFAULTSORT:Hassar, Abubakr
Medieval Moroccan mathematicians
12th-century mathematicians
Year of death unknown
Year of birth missing
12th-century Moroccan writers