The cumulative version of the <a href="https://en.wikipedia.org/wiki/von_Mises_distribution" class="extiw" title="en:von Mises distribution">en:von Mises distribution</a>.
<a href="//commons.wikimedia.org/wiki/User:Rainald62" title="User:Rainald62">Rainald62</a>
<span class="int-own-work" lang="en">Own work</span>