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28 Mathieu Functions and Hill’s EquationModified Mathieu Functions

§28.23 Expansions in Series of Bessel Functions

We use the following notations:

28.23.1 𝒞μ(1) =Jμ,
𝒞μ(2) =Yμ,
𝒞μ(3) =Hμ(1),
𝒞μ(4) =Hμ(2);

compare §10.2(ii). For the coefficients cnν⁡(q) see §28.14. For Anm⁡(q) and Bnm⁡(q) see §28.4.

28.23.2 meν⁡(0,h2)⁢Mν(j)⁡(z,h) =∑n=−∞∞(−1)n⁢c2⁢nν⁡(h2)⁢𝒞ν+2⁢n(j)⁡(2⁢h⁢cosh⁡z),
28.23.3 meν′⁡(0,h2)⁢Mν(j)⁡(z,h) =i⁢tanh⁡z⁢∑n=−∞∞(−1)n⁢(ν+2⁢n)⁢c2⁢nν⁡(h2)⁢𝒞ν+2⁢n(j)⁡(2⁢h⁢cosh⁡z),

valid for all z when j=1, and for ℜ⁡z>0 and |cosh⁡z|>1 when j=2,3,4.

valid for all z when j=1, and for ℜ⁡z>0 and |sinh⁡z|>1 when j=2,3,4.

In the case when ν is an integer

28.23.6 Mc2⁢m(j)⁡(z,h) =(−1)m⁢(ce2⁢m⁡(0,h2))−1⁢∑ℓ=0∞(−1)ℓ⁢A2⁢ℓ2⁢m⁡(h2)⁢𝒞2⁢ℓ(j)⁡(2⁢h⁢cosh⁡z),
28.23.7 Mc2⁢m(j)⁡(z,h) =(−1)m⁢(ce2⁢m⁡(12⁢π,h2))−1⁢∑ℓ=0∞A2⁢ℓ2⁢m⁡(h2)⁢𝒞2⁢ℓ(j)⁡(2⁢h⁢sinh⁡z),
28.23.8 Mc2⁢m+1(j)⁡(z,h) =(−1)m⁢(ce2⁢m+1⁡(0,h2))−1⁢∑ℓ=0∞(−1)ℓ⁢A2⁢ℓ+12⁢m+1⁡(h2)⁢𝒞2⁢ℓ+1(j)⁡(2⁢h⁢cosh⁡z),
28.23.9 Mc2⁢m+1(j)⁡(z,h) =(−1)m+1⁢(ce2⁢m+1′⁡(12⁢π,h2))−1×coth⁡z×∑ℓ=0∞(2⁢ℓ+1)⁢A2⁢ℓ+12⁢m+1⁡(h2)×𝒞2⁢ℓ+1(j)⁡(2⁢h⁢sinh⁡z),
28.23.10 Ms2⁢m+1(j)⁡(z,h) =(−1)m⁢(se2⁢m+1′⁡(0,h2))−1⁢tanh⁡z×∑ℓ=0∞(−1)ℓ⁢(2⁢ℓ+1)⁢B2⁢ℓ+12⁢m+1⁡(h2)×𝒞2⁢ℓ+1(j)⁡(2⁢h⁢cosh⁡z),
28.23.11 Ms2⁢m+1(j)⁡(z,h) =(−1)m⁢(se2⁢m+1⁡(12⁢π,h2))−1⁢∑ℓ=0∞B2⁢ℓ+12⁢m+1⁡(h2)⁢𝒞2⁢ℓ+1(j)⁡(2⁢h⁢sinh⁡z),
28.23.12 Ms2⁢m+2(j)⁡(z,h) =(−1)m⁢(se2⁢m+2′⁡(0,h2))−1⁢tanh⁡z×∑ℓ=0∞(−1)ℓ⁢(2⁢ℓ+2)⁢B2⁢ℓ+22⁢m+2⁡(h2)×𝒞2⁢ℓ+2(j)⁡(2⁢h⁢cosh⁡z),
28.23.13 Ms2⁢m+2(j)⁡(z,h) =(−1)m+1⁢(se2⁢m+2′⁡(12⁢π,h2))−1×coth⁡z×∑ℓ=0∞(2⁢ℓ+2)⁢B2⁢ℓ+22⁢m+2⁡(h2)×𝒞2⁢ℓ+2(j)⁡(2⁢h⁢sinh⁡z).

When j=1, each of the series (28.23.6)–(28.23.13) converges for all z. When j=2,3,4 the series in the even-numbered equations converge for ℜ⁡z>0 and |cosh⁡z|>1, and the series in the odd-numbered equations converge for ℜ⁡z>0 and |sinh⁡z|>1.

For proofs and generalizations, see Meixner and Schäfke (1954, §§2.62 and 2.64).