Homology cycles on a <a href="https://en.wikipedia.org/wiki/torus" class="extiw" title="w:torus">torus</a>. Radius of magenta circle is <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 R=15}"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mi>R</mi><mo>=</mo><mn>15</mn></mstyle></mrow><annotation encoding="application/x-tex">{\displaystyle R=15}</annotation></semantics></math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/a2f076895a95a54e38cc8d28bf64e9da3b7b0061" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.338ex; width:7.187ex; height:2.176ex;" alt="R=15"></span> and radius of red circle is <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 r=5}"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mi>r</mi><mo>=</mo><mn>5</mn></mstyle></mrow><annotation encoding="application/x-tex">{\displaystyle r=5}</annotation></semantics></math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/10587142d854f7a8ef3e5b76e3b3a593846a363f" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.338ex; width:5.31ex; height:2.176ex;" alt="r=5"></span>. Image created in <a href="https://en.wikipedia.org/wiki/maxima_(software)" class="extiw" title="w:maxima (software)">maxima</a> with <a href="https://en.wikipedia.org/wiki/gnuplot" class="extiw" title="w:gnuplot">gnuplot</a> backend and subsequently cropped manually using a text editor.
<a href="//commons.wikimedia.org/wiki/User:Krishnavedala" title="User:Krishnavedala">Krishnavedala</a>
2014-04-15 13:32:31
<span class="int-own-work" lang="en">Own work</span>