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The number π (/ p aɪ / ⓘ; spelled out as "pi") is a mathematical constant, approximately equal to 3.14159, that is the ratio of a circle's circumference to its diameter. It appears in many formulae across mathematics and physics , and some of these formulae are commonly used for defining π , to avoid relying on the definition of the length ...
Archimedes, in his Measurement of a Circle, created the first algorithm for the calculation of π based on the idea that the perimeter of any (convex) polygon inscribed in a circle is less than the circumference of the circle, which, in turn, is less than the perimeter of any circumscribed polygon. He started with inscribed and circumscribed ...
The calculations Archimedes used to approximate the area numerically were laborious, and he stopped with a polygon of 96 sides. A faster method uses ideas of Willebrord Snell ( Cyclometricus , 1621), further developed by Christiaan Huygens ( De Circuli Magnitudine Inventa , 1654), described in Gerretsen & Verdenduin (1983 , pp. 243–250).
Perhaps the most notable hypergeometric inversions are the following two examples, involving the Ramanujan tau function and the Fourier coefficients of the J-invariant (OEIS: A000521): ∑ n = − 1 ∞ j n q n = 256 ( 1 − z + z 2 ) 3 z 2 ( 1 − z ) 2 , {\displaystyle \sum _{n=-1}^{\infty }\mathrm {j} _{n}q^{n}=256{\dfrac {(1-z+z^{2})^{3}}{z ...
Made use of a desk calculator [24] 620: 1947 Ivan Niven: Gave a very elementary proof that π is irrational: January 1947 D. F. Ferguson: Made use of a desk calculator [24] 710: September 1947 D. F. Ferguson: Made use of a desk calculator [24] 808: 1949 Levi B. Smith and John Wrench: Made use of a desk calculator 1,120
For example, German mathematician Ludolph van Ceulen of the 16th century spent a major part of his life calculating the first 35 digits of pi. [22] Using computers and supercomputers , some of the mathematical constants, including π, e , and the square root of 2, have been computed to more than one hundred billion digits.
Archimedes used the method of exhaustion to compute the area inside a circle. Archimedes used the method of exhaustion as a way to compute the area inside a circle by filling the circle with a sequence of polygons with an increasing number of sides and a corresponding increase in area.
In mathematics, Machin-like formulas are a popular technique for computing π (the ratio of the circumference to the diameter of a circle) to a large number of digits.They are generalizations of John Machin's formula from 1706: