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