TITLE: Equation of a 3D spiral
QUESTION [9 upvotes]: I want to know if a 3D spiral, that looks like this:

can be approximated to any sort of geometric primitive that can be described with a known equation, like some sort of twisted cylinder I suppose.
Thanks

REPLY [2 votes]: The tube thickness can also be varied as a function of any desired parameter ( radius, axial length, theta, arc length along tube etc.), the following image is that of of a helix on a cone. Code line is in Mathematica.