Interesting plot of an implicit equation with square root of signum functions

[Micko]

Hello,

recently, I have found so called Batman graph and equation, which basically plots Batman sign.

I have even found Python code that plots this implicit equation.
Code can be found here:
.

And the equation is given here:
[url]http://i.imgur.com/CNy9J.jpg

If you look closelx, you'll see that there are a lot of signum functions and for many numbers that belongs to the graph, there is square root of negative number which is not defined in real number space.
This is a warning sign that equation is not good.
But somehow, if you use this equation it still plots OK.

I cannot explained this. Can you help me understand this?

Python plot just discard nonsence and doesn't plot (naturally) complex numbers.

 

[fresh_42]

It's probably easy to explain if we saw the equations. Firstly the range of the variables have to be taken into account and secondly, some curves are no functions, so it looks as if e.g. $y^2=x$ is used instead of $y=\sqrt{x}$ which would be only one branch.