batman equation in advanced graph app

[Gabriel]

Hi everyone,
yesterday I tried to plot in advanced graph mode the batman equation:
http://math.stackexchange.com/questions/...n-for-real
but I found 2 problems: if I try to plot only the first part: (x/7)^2*sqrt(||x|-3|/(|x|-3))+(y/3)^2*sqrt(|y-3sqrt33/7|/(y-3sqrt33/7))-1=0 (if I made some mistakes please check the link) the plot is incorrect, there are some extra parts( the plot should be like ( ) , the curved parts of the wings, while its more like (| |) ).
Furthermore if I try to plot 2 or more parts (e.g. (f1(x,y))*(f2(x,y))=0 ) I get a weird plot which is neither f1(x,y)=0 nor f2(x,y)=0.
In the plot gallery there are many complicated plots, so why I can't get my batman equation?