TOPICS
Search

Bateman Function


The Bateman function k_nu(x) is the special function defined for real x and nu by the integral

 k_nu(x)=2/piint_0^(pi/2)cos(xtantheta-nutheta)dtheta.
(1)

It was studied by Bateman (1931) in connection with an ordinary differential equation arising in the theory of turbulence.

For x>0, it can also be defined by

 k_nu(x)=(e^(-x))/(Gamma(1+1/2nu))U(-1/2nu,0,2x),
(2)

where Gamma is the gamma function and U is the confluent hypergeometric function of the second kind. At negative even values of nu, the reciprocal gamma function factor is interpreted by continuity, giving k_(-2m)(x)=0 for integers m>=1 and x>0.

The ordinary differential equation satisfied for x>0 is

 xk_nu^('')(x)=(x-nu)k_nu(x).
(3)

The first few even-order cases for x>0 are

k_0(x)=e^(-x)
(4)
k_2(x)=2xe^(-x)
(5)
k_4(x)=2x(x-1)e^(-x).
(6)

At the origin,

 k_nu(0)=(2sin(pinu/2))/(pinu)
(7)

for nu!=0, with k_0(0)=1 (Bateman 1931, Apelblat et al. 2021).


See also

Confluent Hypergeometric Differential Equation, Confluent Hypergeometric Function of the Second Kind, Hypergeometric Function

Explore with Wolfram|Alpha

References

Apelblat, A.; Consiglio, A.; and Mainardi, F. "The Bateman Functions Revisited After 90 Years--A Survey of Old and New Results." Mathematics 9, 1273, 2021. https://doi.org/10.3390/math9111273.Bateman, H. "The k-Function, a Particular Case of the Confluent Hypergeometric Function." Trans. Amer. Math. Soc. 33, 817-831, 1931.Koepf, W. Hypergeometric Summation: An Algorithmic Approach to Summation and Special Function Identities. Braunschweig, Germany: Vieweg, p. 179, 1998.Koepf, W. and Schmersau, D. "Bounded Nonvanishing Functions Are Bateman Functions." Complex Variables 25, 237-259, 1994.

Referenced on Wolfram|Alpha

Bateman Function

Cite this as:

Weisstein, Eric W. "Bateman Function." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/BatemanFunction.html

Subject classifications