Neumann polynomial
In mathematics, the Neumann polynomials, introduced by Carl Neumann for the special case , are a sequence of polynomials in used to expand functions in term of Bessel functions.Abramowitz and Stegun, [https://www.math.sfu.ca/~cbm/aands/page_363.htm p. 363, 9.1.82] ff.
The first few polynomials are
:
:
:
:
:
A general form for the polynomial is
:
and they have the "generating function"
:
where J are Bessel functions.
To expand a function f in the form
:
for
:
where
Examples
An example is the extension
:
or the more general Sonine formula{{citation
| last1 = Erdélyi | first1 = Arthur
| last2 = Magnus | first2 = Wilhelm
| last3 = Oberhettinger | first3 = Fritz
| last4 = Tricomi | first4 = Francesco G.
| mr = 58756
| publisher = McGraw-Hill
| title = Higher Transcendental Functions. Vols. I, II, III
| year = 1955}} II.7.10.1, p.64
:
where
:
:
the confluent hypergeometric function
:
and in particular
:
the index shift formula
:
the Taylor expansion (addition formula)
:
(cf.{{cite book |author-first1=Izrail Solomonovich |author-last1=Gradshteyn |author-link1=Izrail Solomonovich Gradshteyn |author-first2=Iosif Moiseevich |author-last2=Ryzhik |author-link2=Iosif Moiseevich Ryzhik |author-first3=Yuri Veniaminovich |author-last3=Geronimus |author-link3=Yuri Veniaminovich Geronimus |author-first4=Michail Yulyevich |author-last4=Tseytlin |author-link4=Michail Yulyevich Tseytlin |author-first5=Alan |author-last5=Jeffrey |editor-first1=Daniel |editor-last1=Zwillinger |editor-first2=Victor Hugo |editor-last2=Moll |editor-link2=Victor Hugo Moll |translator=Scripta Technica, Inc. |title=Table of Integrals, Series, and Products |publisher=Academic Press, Inc. |date=2015 |orig-year=October 2014 |edition=8 |language=English |isbn=0-12-384933-0 |lccn=2014010276 |title-link=Gradshteyn and Ryzhik |chapter=8.515.1. |page=944}}{{verification failed|date=September 2011|reason=The referenced identity seems to be only superficially similar. It does not directly support the identity here.}}) and the expansion of the integral of the Bessel function,
:
are of the same type.