ISLAMIC MATHEMATICS
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Some examples of the complex symmetries used in Islamic temple decoration
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The Islamic Empire established across Persia, the Middle East,
Central Asia, North Africa, Iberia and parts of India from the 8th
Century onwards made significant contributions towards mathematics. They
were able to draw on and fuse together the mathematical developments of
both
Greece and
India.
One consequence of the Islamic prohibition on depicting the human
form was the extensive use of complex geometric patterns to decorate
their buildings, raising mathematics to the form of an art. In fact,
over time, Muslim artists discovered all the different forms of symmetry
that can be depicted on a 2-dimensional surface.
The Qu’ran itself encouraged the accumulation of knowledge, and a
Golden Age of Islamic science and mathematics flourished throughout the
medieval period from the 9th to 15th Centuries. The House of Wisdom was
set up in Baghdad around 810, and work started almost immediately on
translating the major
Greek and
Indian mathematical and astronomy works into Arabic.
The outstanding Persian mathematician
Muhammad Al-Khwarizmi
was an early Director of the House of Wisdom in the 9th Century, and
one of the greatest of early Muslim mathematicians. Perhaps
Al-Khwarizmi’s
most important contribution to mathematics was his strong advocacy of
the Hindu numerical system (1 - 9 and 0), which he recognized as having
the power and efficiency needed to revolutionize Islamic (and, later,
Western) mathematics, and which was soon adopted by the entire Islamic
world, and later by Europe as well.
Al-Khwarizmi's
other important contribution was algebra, and he introduced the
fundamental algebraic methods of “reduction” and “balancing” and
provided an exhaustive account of solving polynomial equations up to the
second degree. In this way, he helped create the powerful abstract
mathematical language still used across the world today, and allowed a
much more general way of analyzing problems other than just the specific
problems previously considered by the
Indians and
Chinese.
The 10th Century Persian mathematician Muhammad Al-Karaji worked to
extend algebra still further, freeing it from its geometrical heritage,
and introduced the theory of algebraic calculus. Al-Karaji was the first
to use the method of proof by mathematical induction to prove his
results, by proving that the first statement in an infinite sequence of
statements is true, and then proving that, if any one statement in the
sequence is true, then so is the next one.
Among other things, Al-Karaji used mathematical induction to prove
the binomial theorem. A binomial is a simple type of algebraic
expression which has just two terms which are operated on only by
addition, subtraction, multiplication and positive whole-number
exponents, such as (
x +
y)
2.
The co-efficients needed when a binomial is expanded form a symmetrical
triangle, usually referred to as Pascal’s Triangle after the 17th
Century French mathematician
Blaise Pascal, although many other mathematicians had studied it centuries before him in
India, Persia,
China and
Italy, including Al-Karaji.
Some hundred years after Al-Karaji, Omar Khayyam (perhaps better
known as a poet and the writer of the “Rubaiyat”, but an important
mathematician and astronomer in his own right) generalized
Indian
methods for extracting square and cube roots to include fourth, fifth
and higher roots in the early 12th Century. He carried out a systematic
analysis of cubic problems, revealing there were actually several
different sorts of cubic equations. Although he did in fact succeed in
solving cubic equations, and although he is usually credited with
identifying the foundations of algebraic geometry, he was held back from
further advances by his inability to separate the algebra from the
geometry, and a purely algebraic method for the solution of cubic
equations had to wait another 500 years and the Italian mathematicians
del Ferro and
Tartaglia.
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Al-Tusi was a pioneer in the field of spherical trigonometry
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The 13th Century Persian astronomer, scientist and mathematician
Nasir Al-Din Al-Tusi was perhaps the first to treat trigonometry as a
separate mathematical discipline, distinct from astronomy. Building on
earlier work by
Greek mathematicians such as Menelaus of Alexandria and
Indian
work on the sine function, he gave the first extensive exposition of
spherical trigonometry, including listing the six distinct cases of a
right triangle in spherical trigonometry. One of his major mathematical
contributions was the formulation of the famous law of sines for plane
triangles,
a⁄
(sin A) =
b⁄
(sin B) =
c⁄
(sin C),
although the sine law for spherical triangles had been discovered
earlier by the 10th Century Persians Abul Wafa Buzjani and Abu Nasr
Mansur.
Other medieval Muslim mathematicians worthy of note include:
the 9th Century Arab Thabit ibn Qurra, who developed a general
formula by which amicable numbers could be derived, re-discovered much
later by both Fermat and Descartes(amicable
numbers are pairs of numbers for which the sum of the divisors of one
number equals the other number, e.g. the proper divisors of 220 are 1,
2, 4, 5, 10, 11, 20, 22, 44, 55 and 110, of which the sum is 284; and
the proper divisors of 284 are 1, 2, 4, 71, and 142, of which the sum is
220);
the 10th Century Arab mathematician Abul Hasan al-Uqlidisi, who
wrote the earliest surviving text showing the positional use of Arabic
numerals, and particularly the use of decimals instead of fractions
(e.g. 7.375 insead of 73⁄8);
the 10th Century Arab geometer Ibrahim ibn Sinan, who continued Archimedes' investigations of areas and volumes, as well as on tangents of a circle;
the 11th Century Persian Ibn al-Haytham (also known as Alhazen),
who, in addition to his groundbreaking work on optics and physics,
established the beginnings of the link between algebra and geometry, and
devised what is now known as "Alhazen's problem" (he was the first
mathematician to derive the formula for the sum of the fourth powers,
using a method that is readily generalizable); and
the 13th Century Persian Kamal al-Din al-Farisi, who applied the
theory of conic sections to solve optical problems, as well as pursuing
work in number theory such as on amicable numbers, factorization and
combinatorial methods;
the 13th Century Moroccan Ibn al-Banna al-Marrakushi, whose works
included topics such as computing square roots and the theory of
continued fractions, as well as the discovery of the first new pair of
amicable numbers since ancient times (17,296 and 18,416, later
re-discovered by Fermat) and the the first use of algebraic notation since Brahmagupta.
With the stifling influence of the Turkish Ottoman Empire from the
14th or 15th Century onwards, Islamic mathematics stagnated, and further
developments moved to Europe.
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