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Tsu Ch'ung Chi (430-501) was a Chinese mathematician and astronomer. His approximation of pi was 355/113, which is correct to six decimal places. In astronomy, he arrived at the precise time of the solstice by measuring the sun's shadow at noon on days around the solstice.
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Muhammed ibn Musa al-Khwarizmi was a Persian mathematician
of the
9th century whose name comes down to us in the word "algorithm." The
translation of his arithmetic treatises into Latin in the 12th
century brought the advantages of the Indo-Arabic method of
positional counting, including the use of zero, to western Europe,
where counting tables based on the abacus and Latin numerals were
still used. The title of his work Al-jabr wa'l muqabalah has
become our word "algebra." (Detail)
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Adam Riese (1489-1559) was the most famous and influential German
arithmetician of the 16th century, and author of many popular
commercial arithmetic books which made use of Indo-Arabic numerals
instead of counters.(Detail)
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John Napier's (1550-1617) invention of logarithms immensely
facilitated mathematical computations before the age of computers.
Lengthy multiplications and divisions of large numbers were
replaced by the addition or subtraction of their logarithms, which
were calculated and conveniently available in tables of great
accuracy. The Nicaraguan stamp shows astronomical equipment and
the Big Dipper.(Detail)
Astronomical calculations benefitted enormously from the use of accurate
logarithmic tables. Napier's "bones," or sliding scales, later became the slide
rule, an
essential tool for engineers and scientists until replaced by the
hand-held calculator of the 1970's. On the Romanian stamps of 1957
publicizing a Congress of Engineers and Technicians, calipers and
slide rule represent quintessential tools for measurement and calculation. |
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Johannes Kepler (1571-1630) was a German mathematician who is
remembered for his three laws of planetary motion, derived
empirically from Tycho Brahe's data and observations. The laws
describe the solar system as having the sun at the focus of elliptic
planetary orbits. In his writings on conic sections he introduced
the word focus into mathematical language. (s.a. Astronomy and Cosmology I)
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Gottfried Wilhelm Leibniz (1646-1716) developed a system
of the
calculus independently from Newton's, and was unjustly accused of
plagiarism by Newton's followers. His notation flourished in
Europe and is now generally used, while Newton's was preferred in England. The
German stamp
shows a page of his manuscripts. Both Newton and Leibniz had "Big Hair." (Detail)
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Like Eve and Snow White, Isaac Newton (1642-1727) was the
alleged victim of an apple, but with more positive results: the
law of gravitation which not only applies to apples falling from
trees but also describes the relationship of mutual attraction
between planets and celestial bodies in the universe. On the 300th
anniversary of the publication of his Principia Mathematica, Great
Britain issued this set of commemoratives. Planetary motion
according to the inverse square law and optical refraction are
shown on two of the stamps. Newton is also considered the inventor
of the calculus at the same time as Leibniz developed his version
of the calculus; understandably, the German stamp honoring Newton
features his Optics instead.(Detail)
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Leonhard Euler (1707-1783), a Swiss mathematician, worked in number
theory, differential geometry, calculus, differential equations,
and is here commemorated with his polyhedron formula:
