A parameter used to specify an Elliptic Integral of the Third Kind.
See also Amplitude, Elliptic Integral, Modular Angle, Modulus (Elliptic Integral), Nome, Parameter
References
Abramowitz, M. and Stegun, C. A. (Eds.).
Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing.
New York: Dover, p. 590, 1972.