Lommel function

The Lommel differential equation, named after Eugen von Lommel, is an inhomogeneous form of the Bessel differential equation:

$z^2\frac{d^{2}y}{d{z}^2}+z\frac{dy}{dz}+(z^2-{\nu }^2)y=z^{\mu +1}.$

Solutions are given by the Lommel functions s_μ,ν(z) and S_μ,ν(z), introduced by Eugen von Lommel (1880),

$s_{\mu ,\nu }(z)=\frac{\pi }{2}[Y_{\nu }(z)\underset{0}{\overset{z}{\int }}{x}^{\mu }{J}_{\nu }(x)dx-J_{\nu }(z)\underset{0}{\overset{z}{\int }}{x}^{\mu }{Y}_{\nu }(x)dx],$

$S_{\mu ,\nu }(z)=s_{\mu ,\nu }(z)+2^{\mu -1}\Gamma \left(\frac{\mu +\nu +1}{2}\right)\Gamma \left(\frac{\mu -\nu +1}{2}\right)(\sin [(\mu -\nu )\frac{\pi }{2}]J_{\nu }(z)-\cos [(\mu -\nu )\frac{\pi }{2}]Y_{\nu }(z)),$

where J_ν(z) is a Bessel function of the first kind and Y_ν(z) a Bessel function of the second kind.

The s function can also be written as

$s_{\mu ,\nu }(z)=\frac{z^{\mu +1}}{(\mu -\nu +1)(\mu +\nu +1)}{}_1{F}_2(1;\frac{\mu }{2}-\frac{\nu }{2}+\frac{3}{2},\frac{\mu }{2}+\frac{\nu }{2}+\frac{3}{2};-\frac{z^2}{4}),$

where _pF_q is a generalized hypergeometric function.

See also

• Anger function
• Lommel polynomial
• Struve function
• Weber function

References

• .

External links

• Weisstein, Eric W. "Lommel Differential Equation." From MathWorld—A Wolfram Web Resource.
• Weisstein, Eric W. "Lommel Function." From MathWorld—A Wolfram Web Resource.