29 Lamé FunctionsNotation

§29.1 Special Notation

(For other notation see Notation for the Special Functions.)

m,n,p nonnegative integers.
x real variable.
z complex variable.
h,k,ν real parameters, 0<k<1, ν≥−12.
k′ 1−k2, 0<k′<1.
K⁡, K′⁡ complete elliptic integrals of the first kind with moduli k,k′, respectively (see §19.2(ii)).

All derivatives are denoted by differentials, not by primes.

The main functions treated in this chapter are the eigenvalues aν2⁢m⁡(k2), aν2⁢m+1⁡(k2), bν2⁢m+1⁡(k2), bν2⁢m+2⁡(k2), the Lamé functions 𝐸𝑐ν2⁢m⁡(z,k2), 𝐸𝑐ν2⁢m+1⁡(z,k2), 𝐸𝑠ν2⁢m+1⁡(z,k2), 𝐸𝑠ν2⁢m+2⁡(z,k2), and the Lamé polynomials 𝑢𝐸2⁢nm⁡(z,k2), 𝑠𝐸2⁢n+1m⁡(z,k2), 𝑐𝐸2⁢n+1m⁡(z,k2), 𝑑𝐸2⁢n+1m⁡(z,k2), 𝑠𝑐𝐸2⁢n+2m⁡(z,k2), 𝑠𝑑𝐸2⁢n+2m⁡(z,k2), 𝑐𝑑𝐸2⁢n+2m⁡(z,k2), 𝑠𝑐𝑑𝐸2⁢n+3m⁡(z,k2). The notation for the eigenvalues and functions is due to Erdélyi et al. (1955, §15.5.1) and that for the polynomials is due to Arscott (1964b, §9.3.2). The normalization is that of Jansen (1977, §3.1).

Other notations that have been used are as follows: Ince (1940a) interchanges aν2⁢m+1⁡(k2) with bν2⁢m+1⁡(k2). The relation to the Lamé functions Lc⁢ν(m), Ls⁢ν(m)of Jansen (1977) is given by

𝐸𝑐ν2⁢m⁡(z,k2) =(−1)m⁢Lc⁢ν(2⁢m)⁡(ψ,k′2),
𝐸𝑐ν2⁢m+1⁡(z,k2) =(−1)m⁢Ls⁢ν(2⁢m+1)⁡(ψ,k′2),
𝐸𝑠ν2⁢m+1⁡(z,k2) =(−1)m⁢Lc⁢ν(2⁢m+1)⁡(ψ,k′2),
𝐸𝑠ν2⁢m+2⁡(z,k2) =(−1)m⁢Ls⁢ν(2⁢m+2)⁡(ψ,k′2),

where ψ=am⁡(z,k); see §22.16(i). The relation to the Lamé functions Ecνm, Esνm of Ince (1940b) is given by

𝐸𝑐ν2⁢m⁡(z,k2) =cν2⁢m⁡(k2)⁢Ecν2⁢m⁡(z,k2),
𝐸𝑐ν2⁢m+1⁡(z,k2) =cν2⁢m+1⁡(k2)⁢Esν2⁢m+1⁡(z,k2),
𝐸𝑠ν2⁢m+1⁡(z,k2) =sν2⁢m+1⁡(k2)⁢Ecν2⁢m+1⁡(z,k2),
𝐸𝑠ν2⁢m+2⁡(z,k2) =sν2⁢m+2⁡(k2)⁢Esν2⁢m+2⁡(z,k2),

where the positive factors cνm⁡(k2) and sνm⁡(k2) are determined by

(cνm⁡(k2))2 =4π⁢∫0K⁡(𝐸𝑐νm⁡(x,k2))2⁢dx,
(sνm⁡(k2))2 =4π⁢∫0K⁡(𝐸𝑠νm⁡(x,k2))2⁢dx.