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: 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.