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22 Jacobian Elliptic FunctionsNotation

§22.1 Special Notation

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

x,y real variables.
z complex variable.
k modulus. Except in §§22.3(iv), 22.17, and 22.19, 0\leq k\leq 1.
k^{\prime} complementary modulus, k^{2}+{k^{\prime}}^{2}=1. If k\in[0,1], then k^{\prime}\in[0,1].
K, {K^{\prime}} K\left(k\right), {K^{\prime}}\left(k\right)=K\left(k^{\prime}\right) (complete elliptic integrals of the first kind (§19.2(ii))).
q nome. 0\leq q<1 except in §22.17; see also §20.1.
\tau i{K^{\prime}}/K.

All derivatives are denoted by differentials, not primes.

The functions treated in this chapter are the three principal Jacobian elliptic functions \operatorname{sn}\left(z,k\right), \operatorname{cn}\left(z,k\right), \operatorname{dn}\left(z,k\right); the nine subsidiary Jacobian elliptic functions \operatorname{cd}\left(z,k\right), \operatorname{sd}\left(z,k\right), \operatorname{nd}\left(z,k\right), \operatorname{dc}\left(z,k\right), \operatorname{nc}\left(z,k\right), \operatorname{sc}\left(z,k\right), \operatorname{ns}\left(z,k\right), \operatorname{ds}\left(z,k\right), \operatorname{cs}\left(z,k\right); the amplitude function \operatorname{am}\left(x,k\right); Jacobi’s epsilon and zeta functions \mathcal{E}\left(x,k\right) and \mathrm{Z}\left(x|k\right).

The notation \operatorname{sn}\left(z,k\right), \operatorname{cn}\left(z,k\right), \operatorname{dn}\left(z,k\right) is due to Gudermann (1838), following Jacobi (1827); that for the subsidiary functions is due to Glaisher (1882). Other notations for \operatorname{sn}\left(z,k\right) are \mathrm{sn}(z\mathpunct{|}m) and \mathrm{sn}(z,m) with m=k^{2}; see Abramowitz and Stegun (1964) and Walker (1996). Similarly for the other functions.