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Gauss's Constant


The reciprocal of the arithmetic-geometric mean of 1 and sqrt(2),

G=2/piint_0^11/(sqrt(1-x^4))dx
(1)
=2/piint_0^(pi/2)(dtheta)/(sqrt(1+sin^2theta))
(2)
=L/pi
(3)
=1/(M(1,sqrt(2)))
(4)
=(2K(-1))/pi
(5)
=(sqrt(2))/piK(1/(sqrt(2)))
(6)
=theta_4^2(e^(-pi))
(7)
=(2pi)^(-3/2)[Gamma(1/4)]^2
(8)
=3/(2R_D(0,2,1))
(9)
=(2R_F(0,1,2))/pi
(10)
=R_K(1,2)
(11)
=0.83462684167...
(12)

(OEIS A014549), where L is the lemniscate constant, K(k) is the complete elliptic integral of the first kind, theta_4(q) is a Jacobi theta function, Gamma(z) is the gamma function, and R_D, R_F, R_K are Carlson elliptic integrals. This correspondence was first noticed by Gauss, and was the basis for his exploration of the lemniscate function (Borwein and Bailey 2003, pp. 13-15).

Two rapidly converging series for G are given by

G=[sum_(n=-infty)^(infty)(-1)^ne^(-pin^2)]^2
(13)
=2^(5/4)e^(-pi/3)[sum_(n=-infty)^(infty)(-1)^ne^(-2pi(3n+1)n)]^2
(14)

(Finch 2003, p. 421).

Gauss's constant has continued fraction [0, 1, 5, 21, 3, 4, 14, 1, 1, 1, 1, 1, 3, 1, 15, ...] (OEIS A053002).

The inverse of Gauss's constant is given by

 M=1/G=1.1981402347355922074399...
(15)

(OEIS A053004; Finch 2003, p. 420; Borwein and Bailey 2003, p. 13), which has [1, 5, 21, 3, 4, 14, 1, 1, 1, 1, 1, 3, 1, 15, 1, ...] (OEIS A053003).

The value

 M/(sqrt(2))=0.847213...
(16)

(OEIS A097057) is sometimes called the ubiquitous constant (Spanier and Oldham 1987; Schroeder 1994; Finch 2003, p. 421), and

 M/2=0.599070...
(17)

(OEIS A076390) is sometimes called the second lemniscate constant (Finch 2003, p. 421).

Gauss's constants G and M are related to the lemniscate constant L by

L=piG
(18)
=pi/M
(19)

(Finch 2003, p. 420).


See also

Arithmetic-Geometric Mean, Gauss-Kuzmin-Wirsing Constant, Lemniscate Constant, Lemniscate Function, Pythagoras's Constant

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References

Borwein, J. M. and Borwein, P. B. Pi & the AGM: A Study in Analytic Number Theory and Computational Complexity. New York: Wiley, p. 5, 1987.Borwein, J. and Bailey, D. Mathematics by Experiment: Plausible Reasoning in the 21st Century. Wellesley, MA: A K Peters, 2003.Goldman, J. R. The Queen of Mathematics: An Historically Motivated Guide to Number Theory. Wellesley, MA: A K Peters, p. 92, 1997.Finch, S. R. Mathematical Constants. Cambridge, England: Cambridge University Press, 2003.Gosper, R. W. "A Calculus of Series Rearrangements." In Algorithms and Complexity: New Directions and Recent Results. Proc. 1976 Carnegie-Mellon Conference (Ed. J. F. Traub). New York: Academic Press, pp. 121-151, 1976.Lewanowicz, S. and Paszowski, S. "An Analytic Method for Convergence Acceleration of Certain Hypergeometric Series." Math. Comput. 64, 691-713, 1995.Schroeder, M. "How Probable is Fermat's Last Theorem?" Math. Intell. 16, 19-20, 1994.Sloane, N. J. A. Sequences A014549, A053002, A053003, A053004, A076390, and A097057 in "The On-Line Encyclopedia of Integer Sequences."Spanier, J. and Oldham, K. B. "The Kelvin Functions." Ch. 55 in An Atlas of Functions. Washington, DC: Hemisphere, 1987.Todd, J. "The Lemniscate Constant." Comm. ACM 18, 14-19 and 462, 1975.

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Gauss's Constant

Cite this as:

Weisstein, Eric W. "Gauss's Constant." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/GausssConstant.html

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