Is Adobe Acrobat's icon a special function? 
It looks like a function in polar coordinates. 
Is it a special function ?
 A: 
Thanks you guys! Very grateful for this discussion. This is just what I was looking for. It's a Cinema4D Formula Object. Did a little Z tweaking to make it loop like Acrobat Logo. Apologies for my home made Z formula, kinda hacked at it. Sure there is a better solution.


*

*$X= 300 \cdot \cos(t) \cdot (\sin(t+.5) +\cos(3t+.5))$

*$Y= 300 \cdot \sin(t) \cdot (\sin(t+.5)  -\cos(3t+.5))$

*$Z= 10 \cdot \cos(t) \cdot 10 \cdot \sin(t)$

*TMin $=-1.571$

*TMin $=1.571$

A: The logo dates back to Adobe Reader v1.0. (link) I always thought it was chosen simply because it looks like the letter A for Acrobat. 
A parametric function that approximates the logo is:
$$x(t)=5\cos(t)\times \left(\sin(t+.5)+\cos(3t+.5) \right) \\
y(t)=5\sin(t)\times \left(\sin(t+.5)-\cos(3t+.5) \right) $$

A: It bears a strong resemblance to (in cartesian coordinates)
$ x = \cos(t) + 3 \cos(2 t)/4, y = \sin(t) - 3 \sin(2 t)/4$ 
but not quite as symmetric.

A: It looks a bit like a deltoid, which belongs to the family of Kakeya sets. It was thought to be the solution to the problem of finding the minimal area you need to rotate a needle in the plane.
