number pi عدد ِ پی adad-e pi (π)
*Fr.: nombre pi (π)*
Symbol, π, for the ratio of the circumference of a circle to its
diameter in Euclidean geometry; a fundamental mathematical
constant, equal to 3.14159... π is an → *irrational number*
(Lambert, 1761) and also a → *transcendental number*
(von Lindemann, 1882). The most accurate determination of π prior to the Scientific
Revolution belongs to the Iranian mathematician Jamshid Kashani, who gave 16 correct
decimal places in A.D. 1424. With the advent of → *calculus*
and more recently the invention of powerful computers, the
decimal representation of π has now been computed to more than 10^{12}
digits. The π notation, representing the first letter of the Gk. word
περιμετρον
→ *perimeter*,
was first used by the British mathematician William Jones (1675-1749) in 1706.
Its use was generalized after its adoption by the Swiss mathematician Leonard Euler (1707-1783)
in 1737; → *number*. |