Lommel function
The Lommel differential equation is an inhomogeneous form of the Bessel differential equation:
Two solutions are given by the Lommel functions sμ,ν(z) and Sμ,ν(z), introduced by Eugen von Lommel (1880),
where Jν(z) is a Bessel function of the first kind, and Yν(z) a Bessel function of the second kind.
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