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10 Bessel FunctionsBessel and Hankel Functions

§10.16 Relations to Other Functions

Elementary Functions

10.16.1 J12⁡(z) =Y−12⁡(z)=(2π⁢z)12⁢sin⁡z,
J−12⁡(z) =−Y12⁡(z)=(2π⁢z)12⁢cos⁡z,
10.16.2 H12(1)⁡(z) =−i⁢H−12(1)⁡(z)=−i⁢(2π⁢z)12⁢ei⁢z,
H12(2)⁡(z) =i⁢H−12(2)⁡(z)=i⁢(2π⁢z)12⁢e−i⁢z.

For these and general results when ν is half an odd integer see §§10.47(ii) and 10.49(i).

Airy Functions

See §§9.6(i) and 9.6(ii).

Parabolic Cylinder Functions

With the notation of §12.14(i),

10.16.3 J14⁡(z) =−2−14⁢π−12⁢z−14⁢(W⁡(0,2⁢z12)−W⁡(0,−2⁢z12)),
J−14⁡(z) =2−14⁢π−12⁢z−14⁢(W⁡(0,2⁢z12)+W⁡(0,−2⁢z12)).
10.16.4 J34⁡(z) =−2−14⁢π−12⁢z−34⁢(W′⁡(0,2⁢z12)−W′⁡(0,−2⁢z12)),
J−34⁡(z) =−2−14⁢π−12⁢z−34⁢(W′⁡(0,2⁢z12)+W′⁡(0,−2⁢z12)).

Principal values on each side of these equations correspond.

Confluent Hypergeometric Functions

10.16.5 Jν⁡(z)=(12⁢z)ν⁢e∓i⁢zΓ⁡(ν+1)⁢M⁡(ν+12,2⁢ν+1,±2⁢i⁢z),

For the functions M and U see §13.2(i).

10.16.7 Jν⁡(z)=e∓(2⁢ν+1)⁢π⁢i/422⁢ν⁢Γ⁡(ν+1)⁢(2⁢z)−12⁢M0,ν⁡(±2⁢i⁢z),
2⁢ν≠−1,−2,−3,…,

For the functions M0,ν and W0,ν see §13.14(i).

In all cases principal branches correspond at least when |ph⁡z|≤12⁢π.

Generalized Hypergeometric Functions

With 𝐅 as in §15.2(i), and with z and ν fixed,

10.16.10 Jν⁡(z)=(12⁢z)ν⁢lim𝐅⁡(λ,μ;ν+1;−z2/(4⁢λ⁢μ)),

as λ and μ→∞ in ℂ. For this result see Watson (1944, §5.7).