The equation can be any mathematical equation including the letters x, y, z, r, phi, theta and v, where r, phi, and theta are the radius, theta, and phi for polar coordiinates. v is a constant defined by the number input below the equation. If you do not include an = symbol, it will be assumed that the function equals 0.
Here is a list of operators:
Division by zero causes solid asymptotes to appear. To remove these, do your best to eliminate division by variables by multiplying them on the other side of the equal sign.
Due to precision issues, sometimes there will be strange, circular artifacts. This usually occurs when the function approaches an asymptote, or two areas of the surface come very close together. If you zoom in or rotate around, you can usually piece together what the graph looks like for the most part.