This picture represents the result of a conformal transformation of the complex plane tiled by a clock. Here: the <a href="https://en.wikipedia.org/wiki/en:Trigonometric_functions" class="extiw" title="w:en:Trigonometric functions">tangent function</a> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle z\mapsto \tan(z)}"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mi>z</mi><mo stretchy="false">↦<!-- ↦ --></mo><mi>tan</mi><mo>⁡<!-- ⁡ --></mo><mo stretchy="false">(</mo><mi>z</mi><mo stretchy="false">)</mo></mstyle></mrow><annotation encoding="application/x-tex">{\displaystyle z\mapsto \tan(z)}</annotation></semantics></math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/db8a49663cefc767e095516c2002b767af0d92a0" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.838ex; width:10.959ex; height:2.843ex;" alt="{\displaystyle z\mapsto \tan(z)}"></span>.
Christian Mercat
I created this picture from a clock with French writing