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14 Legendre and Related FunctionsReal Arguments

§14.5 Special Values

Contents
  1. §14.5(i) x=0
  2. §14.5(ii) μ=0, ν=0,1
  3. §14.5(iii) μ=±12
  4. §14.5(iv) μ=−ν
  5. §14.5(v) μ=0, ν=±12
  6. §14.5(vi) Addendum to §14.5(ii): μ=0, ν=2

§14.5(i) x=0

14.5.1 𝖯νμ⁡(0)=2μ⁢π1/2Γ⁡(12⁢ν−12⁢μ+1)⁢Γ⁡(12−12⁢ν−12⁢μ),
14.5.2 d𝖯νμ⁡(x)dx|x=0=−2μ+1⁢π1/2Γ⁡(12⁢ν−12⁢μ+12)⁢Γ⁡(−12⁢ν−12⁢μ),
14.5.3 𝖰νμ⁡(0)=−2μ−1⁢π1/2⁢sin⁡(12⁢(ν+μ)⁢π)⁢Γ⁡(12⁢ν+12⁢μ+12)Γ⁡(12⁢ν−12⁢μ+1),
ν+μ≠−1,−2,−3,…,
14.5.4 d𝖰νμ⁡(x)dx|x=0=2μ⁢π1/2⁢cos⁡(12⁢(ν+μ)⁢π)⁢Γ⁡(12⁢ν+12⁢μ+1)Γ⁡(12⁢ν−12⁢μ+12),
ν+μ≠−1,−2,−3,….

§14.5(ii) μ=0, ν=0,1

14.5.5 𝖯0⁡(x)=P0⁡(x)=1,
14.5.6 𝖯1⁡(x)=P1⁡(x)=x.
14.5.7 𝖰0⁡(x) =12⁢ln⁡(1+x1−x),
14.5.8 𝖰1⁡(x) =x2⁢ln⁡(1+x1−x)−1.
14.5.9 𝑸0⁡(x) =12⁢ln⁡(x+1x−1),
14.5.10 𝑸1⁡(x) =x2⁢ln⁡(x+1x−1)−1.

For the corresponding formulas when ν=2 see §14.5(vi).

§14.5(iii) μ=±12

In this subsection and the next two, 0<θ<π and ξ>0.

14.5.11 𝖯ν1/2⁡(cos⁡θ) =(2π⁢sin⁡θ)1/2⁢cos⁡((ν+12)⁢θ),
14.5.12 𝖯ν−1/2⁡(cos⁡θ) =(2π⁢sin⁡θ)1/2⁢sin⁡((ν+12)⁢θ)ν+12,
14.5.13 𝖰ν1/2⁡(cos⁡θ) =−(π2⁢sin⁡θ)1/2⁢sin⁡((ν+12)⁢θ),
14.5.14 𝖰ν−1/2⁡(cos⁡θ)=(π2⁢sin⁡θ)1/2⁢cos⁡((ν+12)⁢θ)ν+12.
14.5.15 Pν1/2⁡(cosh⁡ξ) =(2π⁢sinh⁡ξ)1/2⁢cosh⁡((ν+12)⁢ξ),
14.5.16 Pν−1/2⁡(cosh⁡ξ) =(2π⁢sinh⁡ξ)1/2⁢sinh⁡((ν+12)⁢ξ)ν+12,
14.5.17 𝑸ν±1/2⁡(cosh⁡ξ) =(π2⁢sinh⁡ξ)1/2⁢exp⁡(−(ν+12)⁢ξ)Γ⁡(ν+32).

§14.5(iv) μ=−ν

14.5.18 𝖯ν−ν⁡(cos⁡θ) =(sin⁡θ)ν2ν⁢Γ⁡(ν+1),
14.5.19 Pν−ν⁡(cosh⁡ξ) =(sinh⁡ξ)ν2ν⁢Γ⁡(ν+1).

§14.5(v) μ=0, ν=±12

In this subsection K⁡(k) and E⁡(k) denote the complete elliptic integrals of the first and second kinds; see §19.2(ii).

14.5.21 𝖯−12⁡(cos⁡θ) =2π⁢K⁡(sin⁡(12⁢θ)),
14.5.22 𝖰12⁡(cos⁡θ) =K⁡(cos⁡(12⁢θ))−2⁢E⁡(cos⁡(12⁢θ)),
14.5.23 𝖰−12⁡(cos⁡θ) =K⁡(cos⁡(12⁢θ)).
14.5.26 𝑸12⁡(cosh⁡ξ)=2⁢π−1/2⁢cosh⁡ξ⁢sech⁡(12⁢ξ)⁢K⁡(sech⁡(12⁢ξ))−4⁢π−1/2⁢cosh⁡(12⁢ξ)⁢E⁡(sech⁡(12⁢ξ)),

§14.5(vi) Addendum to §14.5(ii): μ=0, ν=2

14.5.28 𝖯2⁡(x) =P2⁡(x)=3⁢x2−12,
14.5.29 𝖰2⁡(x) =3⁢x2−14⁢ln⁡(1+x1−x)−32⁢x,
14.5.30 𝑸2⁡(x) =3⁢x2−18⁢ln⁡(x+1x−1)−34⁢x.