BesselJ[n, z] gives the Bessel function of the first kind .
Mathematical function (see Section A.3.10).
satisfies the differential equation .
BesselJ[n, z] has a branch cut discontinuity in the complex z plane running from to .
FullSimplify and FunctionExpand include transformation rules for BesselJ.
See The Mathematica Book: Section 3.2.10.
See also: BesselY, StruveH, BesselK.
Related package: NumericalMath`BesselZeros`.