A Modulus such that
Abel (quoted in Whittaker and Watson 1990, p. 525) proved that if is an
Integer, or more generally whenever
See also Elliptic Integral Singular Value, Elliptic Integral of the First Kind, Elliptic Lambda Function, Modulus (Elliptic Integral)
Whittaker, E. T. and Watson, G. N. A Course in Modern Analysis, 4th ed. Cambridge, England: Cambridge
University Press, pp. 524-528, 1990.