InverseJacobiSN, InverseJacobiCN, ...
InverseJacobiSN[v, m], InverseJacobiCN[v, m], etc. give the inverse Jacobi elliptic functions etc.
There are a total of twelve functions, with names of the form InverseJacobiPQ, where P and Q can be any distinct pair of the letters S, C, D and N.
Mathematical functions (see Section A.3.10).
gives the value of for which .
The inverse Jacobi elliptic functions are related to elliptic integrals.
See The Mathematica Book: Section 3.2.11.