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11 Struve and Related FunctionsStruve and Modified Struve Functions

§11.4 Basic Properties

Contents
  1. §11.4(i) Half-Integer Orders
  2. §11.4(ii) Inequalities
  3. §11.4(iii) Analytic Continuation
  4. §11.4(iv) Expansions in Series of Bessel Functions
  5. §11.4(v) Recurrence Relations and Derivatives
  6. §11.4(vi) Derivatives with Respect to Order
  7. §11.4(vii) Zeros

§11.4(i) Half-Integer Orders

For n=0,1,2,…,

11.4.1 𝐊n+12⁡(z)=(2π⁢z)12⁢∑m=0n(2⁢m)!⁢ 2−2⁢mm!⁢(n−m)!⁢(12⁢z)n−2⁢m,
11.4.2 𝐋n+12⁡(z)=I−n−12⁡(z)−(2π⁢z)12⁢∑m=0n(−1)m⁢(2⁢m)!⁢ 2−2⁢mm!⁢(n−m)!⁢(12⁢z)n−2⁢m,
11.4.3 𝐇−n−12⁡(z) =(−1)n⁢Jn+12⁡(z),
11.4.4 𝐋−n−12⁡(z) =In+12⁡(z).
11.4.5 𝐇12⁡(z) =(2π⁢z)12⁢(1−cos⁡z),
11.4.6 𝐇−12⁡(z) =(2π⁢z)12⁢sin⁡z,
11.4.9 𝐇32⁡(z)=(z2⁢π)12⁢(1+2z2)−(2π⁢z)12⁢(sin⁡z+cos⁡zz),
11.4.10 𝐇−32⁡(z)=(2π⁢z)12⁢(cos⁡z−sin⁡zz),
11.4.11 𝐋32⁡(z)=−(z2⁢π)12⁢(1−2z2)+(2π⁢z)12⁢(sinh⁡z−cosh⁡zz),

§11.4(ii) Inequalities

11.4.13 𝐇ν⁡(x)≥0,
x>0, ν≥12.
11.4.14 𝐇ν⁡(z)=2⁢(12⁢z)ν+1π⁢Γ⁡(ν+32)⁢(1+ϑ),
ν≠−32,−52,−72,…,

where

11.4.15 |ϑ|<23⁢exp⁡(14⁢|z|2|ν0+32|−1),

and |ν0+32| is the smallest of the numbers |ν+32|, |ν+52|, |ν+92|,….

§11.4(iii) Analytic Continuation

§11.4(iv) Expansions in Series of Bessel Functions

11.4.18 𝐇ν⁡(z)=4π1/2⁢Γ⁡(ν+12)⁢∑k=0∞(2⁢k+ν+1)⁢Γ⁡(k+ν+1)k!⁢(2⁢k+1)⁢(2⁢k+2⁢ν+1)⁢J2⁢k+ν+1⁡(z),
ν≠−1,−2,−3,…,
11.4.20 𝐇ν⁡(z)=(12⁢z)ν+12Γ⁡(ν+12)⁢∑k=0∞(12⁢z)kk!⁢(k+ν+12)⁢Jk+12⁡(z),
11.4.21 𝐇0⁡(z)=4π⁢∑k=0∞J2⁢k+1⁡(z)2⁢k+1=2⁢∑k=0∞(−1)k⁢Jk+122⁡(12⁢z),
11.4.22 𝐇1⁡(z)=2π⁢(1−J0⁡(z))+4π⁢∑k=1∞J2⁢k⁡(z)4⁢k2−1=4⁢∑k=0∞J2⁢k+12⁡(12⁢z)⁢J2⁢k+32⁡(12⁢z).

For these and further results see Luke (1969b, §9.4.5), and §10.23(iii).

§11.4(v) Recurrence Relations and Derivatives

11.4.23 𝐇ν−1⁡(z)+𝐇ν+1⁡(z) =2⁢νz⁢𝐇ν⁡(z)+(12⁢z)νπ⁢Γ⁡(ν+32),
11.4.24 𝐇ν−1⁡(z)−𝐇ν+1⁡(z) =2⁢𝐇ν′⁡(z)−(12⁢z)νπ⁢Γ⁡(ν+32),
11.4.25 𝐋ν−1⁡(z)−𝐋ν+1⁡(z) =2⁢νz⁢𝐋ν⁡(z)+(12⁢z)νπ⁢Γ⁡(ν+32),
11.4.26 𝐋ν−1⁡(z)+𝐋ν+1⁡(z) =2⁢𝐋ν′⁡(z)−(12⁢z)νπ⁢Γ⁡(ν+32).
11.4.27 ddz⁡(zν⁢𝐇ν⁡(z))=zν⁢𝐇ν−1⁡(z),
11.4.28 ddz⁡(z−ν⁢𝐇ν⁡(z))=2−νπ⁢Γ⁡(ν+32)−z−ν⁢𝐇ν+1⁡(z),
11.4.29 ddz⁡(zν⁢𝐋ν⁡(z))=zν⁢𝐋ν−1⁡(z),
11.4.30 ddz⁡(z−ν⁢𝐋ν⁡(z))=2−νπ⁢Γ⁡(ν+32)+z−ν⁢𝐋ν+1⁡(z).
11.4.31 ℋν−m⁡(z)=zm−ν⁢(1z⁢ddz)m⁡(zν⁢ℋν⁡(z)),
m=1,2,3,…,

where ℋν⁡(z) denotes either 𝐇ν⁡(z) or 𝐋ν⁡(z).

11.4.32 𝐇0′⁡(z) =2π−𝐇1⁡(z),
ddz⁡(z⁢𝐇1⁡(z)) =z⁢𝐇0⁡(z),
11.4.33 𝐋0′⁡(z) =2π+𝐋1⁡(z),
ddz⁡(z⁢𝐋1⁡(z)) =z⁢𝐋0⁡(z).

§11.4(vi) Derivatives with Respect to Order

For derivatives with respect to the order ν, see Apelblat (1989) and Brychkov and Geddes (2005).

§11.4(vii) Zeros

For properties of zeros of 𝐇ν⁡(x) see Steinig (1970).

For asymptotic expansions of zeros of 𝐇0⁡(x) see MacLeod (2002a).