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11 Struve and Related FunctionsRelated Functions

§11.10 Anger–Weber Functions

Contents
  1. §11.10(i) Definitions
  2. §11.10(ii) Differential Equations
  3. §11.10(iii) Maclaurin Series
  4. §11.10(iv) Graphics
  5. §11.10(v) Interrelations
  6. §11.10(vi) Relations to Other Functions
  7. §11.10(vii) Special Values
  8. §11.10(viii) Expansions in Series of Products of Bessel Functions
  9. §11.10(ix) Recurrence Relations and Derivatives
  10. §11.10(x) Integrals and Sums

§11.10(i) Definitions

The Anger function 𝐉ν⁡(z) and Weber function 𝐄ν⁡(z) are defined by

11.10.1 𝐉ν⁡(z)=1π⁢∫0πcos⁡(ν⁢θ−z⁢sin⁡θ)⁢dθ,
11.10.2 𝐄ν⁡(z)=1π⁢∫0πsin⁡(ν⁢θ−z⁢sin⁡θ)⁢dθ.

Each is an entire function of z and ν. Also,

11.10.3 1π⁢∫02⁢πcos⁡(ν⁢θ−z⁢sin⁡θ)⁢dθ=(1+cos⁡(2⁢π⁢ν))⁢𝐉ν⁡(z)+sin⁡(2⁢π⁢ν)⁢𝐄ν⁡(z).

The associated Anger–Weber function 𝐀ν⁡(z) is defined by

11.10.4 𝐀ν⁡(z)=1π⁢∫0∞e−ν⁢t−z⁢sinh⁡t⁢dt,
ℜ⁡z>0.

(11.10.4) also applies when ℜ⁡z=0 and ℜ⁡ν>0.

§11.10(ii) Differential Equations

The Anger and Weber functions satisfy the inhomogeneous Bessel differential equation

11.10.5 d2wdz2+1z⁢dwdz+(1−ν2z2)⁢w=f⁡(ν,z),

where

11.10.6 f⁡(ν,z)=(z−ν)π⁢z2⁢sin⁡(π⁢ν),
w=𝐉ν⁡(z),

or

11.10.7 f⁡(ν,z)=−1π⁢z2⁢(z+ν+(z−ν)⁢cos⁡(π⁢ν)),
w=𝐄ν⁡(z).

§11.10(iii) Maclaurin Series

11.10.8 𝐉ν⁡(z)=cos⁡(12⁢π⁢ν)⁢S1⁡(ν,z)+sin⁡(12⁢π⁢ν)⁢S2⁡(ν,z),
11.10.9 𝐄ν⁡(z)=sin⁡(12⁢π⁢ν)⁢S1⁡(ν,z)−cos⁡(12⁢π⁢ν)⁢S2⁡(ν,z),

where

11.10.10 S1⁡(ν,z)=∑k=0∞(−1)k⁢(12⁢z)2⁢kΓ⁡(k+12⁢ν+1)⁢Γ⁡(k−12⁢ν+1),
11.10.11 S2⁡(ν,z)=∑k=0∞(−1)k⁢(12⁢z)2⁢k+1Γ⁡(k+12⁢ν+32)⁢Γ⁡(k−12⁢ν+32).

These expansions converge absolutely for all finite values of z.

§11.10(iv) Graphics

See accompanying text
Figure 11.10.1: Anger function 𝐉ν⁡(x) for −8≤x≤8 and ν=0,12,1,32. Magnify
See accompanying text
Figure 11.10.2: Weber function 𝐄ν⁡(x) for −8≤x≤8 and ν=0,12,1,32. Magnify
See accompanying text
Figure 11.10.3: Anger function 𝐉ν⁡(x) for −10≤x≤10 and 0≤ν≤5. Magnify 3D Help
See accompanying text
Figure 11.10.4: Weber function 𝐄ν⁡(x) for −10≤x≤10 and 0≤ν≤5. Magnify 3D Help

§11.10(v) Interrelations

11.10.12 𝐉ν⁡(−z) =𝐉−ν⁡(z),
𝐄ν⁡(−z) =−𝐄−ν⁡(z).
11.10.13 sin⁡(π⁢ν)⁢𝐉ν⁡(z) =cos⁡(π⁢ν)⁢𝐄ν⁡(z)−𝐄−ν⁡(z),
11.10.14 sin⁡(π⁢ν)⁢𝐄ν⁡(z) =𝐉−ν⁡(z)−cos⁡(π⁢ν)⁢𝐉ν⁡(z).

§11.10(vi) Relations to Other Functions

11.10.17 𝐉ν⁡(z) =sin⁡(π⁢ν)π⁢(s0,ν⁡(z)−ν⁢s−1,ν⁡(z)),
11.10.18 𝐄ν⁡(z) =−1π⁢(1+cos⁡(π⁢ν))⁢s0,ν⁡(z)−νπ⁢(1−cos⁡(π⁢ν))⁢s−1,ν⁡(z).
11.10.19 𝐉−12⁡(z) =𝐄12⁡(z)=(12⁢π⁢z)−12⁢(A+⁡(χ)⁢cos⁡z−A−⁡(χ)⁢sin⁡z),
11.10.20 𝐉12⁡(z) =−𝐄−12⁡(z)=(12⁢π⁢z)−12⁢(A+⁡(χ)⁢sin⁡z+A−⁡(χ)⁢cos⁡z),

where

11.10.21 A±⁡(χ) =C⁡(χ)±S⁡(χ),
χ =(2⁢z/π)12.

For the Fresnel integrals C and S see §7.2(iii).

For n=1,2,3,…,

11.10.22 𝐄n⁡(z)=−𝐇n⁡(z)+1π⁢∑k=0m1Γ⁡(k+12)Γ⁡(n+12−k)⁢(12⁢z)n−2⁢k−1,

and

11.10.23 𝐄−n⁡(z)=−𝐇−n⁡(z)+(−1)n+1π⁢∑k=0m2Γ⁡(n−k−12)Γ⁡(k+32)⁢(12⁢z)−n+2⁢k+1,

where

11.10.24 m1 =⌊12⁢n−12⌋,
m2 =⌈12⁢n−32⌉.

§11.10(vii) Special Values

11.10.25 𝐉ν⁡(0) =sin⁡(π⁢ν)π⁢ν, 𝐄ν⁡(0) =1−cos⁡(π⁢ν)π⁢ν.
11.10.26 𝐄0⁡(z) =−𝐇0⁡(z), 𝐄1⁡(z) =2π−𝐇1⁡(z).
11.10.29 𝐉n⁡(z)=Jn⁡(z),
n∈ℤ.

§11.10(viii) Expansions in Series of Products of Bessel Functions

11.10.30 𝐉ν⁡(z)=2⁢sin⁡(12⁢ν⁢π)⁢∑k=0∞(−1)k⁢Jk−12⁢ν+12⁡(12⁢z)⁢Jk+12⁢ν+12⁡(12⁢z)+2⁢cos⁡(12⁢ν⁢π)⁢∑′k=0′∞′⁢(−1)k⁢Jk−12⁢ν⁡(12⁢z)⁢Jk+12⁢ν⁡(12⁢z),
11.10.31 𝐄ν⁡(z)=−2⁢cos⁡(12⁢ν⁢π)⁢∑k=0∞(−1)k⁢Jk−12⁢ν+12⁡(12⁢z)⁢Jk+12⁢ν+12⁡(12⁢z)+2⁢sin⁡(12⁢ν⁢π)⁢∑′k=0′∞′⁢(−1)k⁢Jk−12⁢ν⁡(12⁢z)⁢Jk+12⁢ν⁡(12⁢z),

where the prime on the second summation symbols means that the first term is to be halved.

§11.10(ix) Recurrence Relations and Derivatives

11.10.32 𝐉ν−1⁡(z)+𝐉ν+1⁡(z)=2⁢νz⁢𝐉ν⁡(z)−2π⁢z⁢sin⁡(π⁢ν),
11.10.33 𝐄ν−1⁡(z)+𝐄ν+1⁡(z)=2⁢νz⁢𝐄ν⁡(z)−2π⁢z⁢(1−cos⁡(π⁢ν)).
11.10.34 2⁢𝐉ν′⁡(z) =𝐉ν−1⁡(z)−𝐉ν+1⁡(z),
11.10.35 2⁢𝐄ν′⁡(z) =𝐄ν−1⁡(z)−𝐄ν+1⁡(z),
11.10.36 z⁢𝐉ν′⁡(z)±ν⁢𝐉ν⁡(z)=±z⁢𝐉ν∓1⁡(z)±sin⁡(π⁢ν)π,
11.10.37 z⁢𝐄ν′⁡(z)±ν⁢𝐄ν⁡(z)=±z⁢𝐄ν∓1⁡(z)±(1−cos⁡(π⁢ν))π.

§11.10(x) Integrals and Sums

For collections of integral representations and integrals see Erdélyi et al. (1954a, §§4.19 and 5.17), Marichev (1983, pp. 194–195 and 214–215), Oberhettinger (1972, p. 128), Oberhettinger (1974, §§1.12 and 2.7), Oberhettinger (1990, pp. 105 and 189–190), Prudnikov et al. (1990, §§1.5 and 2.8), Prudnikov et al. (1992a, §3.18), Prudnikov et al. (1992b, §3.18), and Zanovello (1977).

For sums see Hansen (1975, pp. 456–457) and Prudnikov et al. (1990, §§6.4.2–6.4.3).