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writer.,"
Both algebra, in the true sense of the
term, and the term itself (al-jabr) we
owe to him. Apart from mathematics,
Khawarazmi also did pioneer work in the
fields of astronomy, geography and the
theory of music.
It was due to
another exponent of Arab civilization,
Omar Khayyam (1040-1123), that algebra
made an enormous leap forward, two
centuries after Khawarazmi. Known in the
West as the author of Rubayat, a
poem made famous by Edward Fitzgerald's
translation, he was admired in the East
mainly as a mathematician. In his use of
analytical geometry, he anticipated the
geometry of Descartes. Commissioned by
the Seijuk Sultan Halikshah to reform the
Persian calendar, he prepared a calendar
said to be more accurate than the
Gregorian one in use to the present day.
For, whereas the latter leads to an error
of one day in 3,300 years, in Omar
Khayyam's calendar that error is one day
in 5,000 years.
Because of their Islamic faith, it was
essential for the Arabs to obtain a more
precise knowledge of astronomy and
geography than was already avail-
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able: a
Muslim is obliged to perform a number of
religious observances with distinctly
astronomicgeographical implications. When
he prays, he must face Mecca; if he
wishes to perform the pilgrimage to
Mecca, he must first know in what
direction and what distance he will have
to travel. Yet a thousand years ago such
ajourney might take months or even years,
for the would-be pilgrim might have been
living in Spain, Sicily or Asia Minor-all
of these forming parts of the medieval
Arab Empire. During Ramadan, the month of
fast, when between sunrise and sunset he
has to abstain from food and drink, he
must know in advance the precise moment
at which the moon rises and sets. All
these functions required a detailed
knowledge of astronomy and geography.
It was, thus,
under the great Caliph Ma'mun (813-833)
that the Arabs set out upon their
astronomical investigations. Ma'mun-a son
of Harun al-Rashid of Arabian Nights fame-built
a special observatory in Palmyra, Syria,
and gradually, his scientists determined
the length of a degree, thus establishing
longitude and latitude.
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