Jacobi ns
From specialfunctionswiki
The $\mathrm{ns}$ function is defined by $$\mathrm{ns}(u)=\dfrac{1}{\mathrm{sn}(u)},$$ where $\mathrm{sn}$ denotes the Jacobi sn function.
Domain coloring of $\mathrm{ns}$ corresponding to $m=0.8$.
References
Special functions by Leon Hall