Yay! It’s Fractal Friday! (It’s not, I just made that up.) But anyway, courtesy of Christopher Night, you can play around with this Julia set fractal. It works in a desktop browser (by moving the mouse) or on your phone (by dragging your finger).

The Julia set, if you don’t remember, goes thusly: Let f(z) be a complex rational function from the plane into itself, that is, f(z)=p(z)/q(z) f(z)=p(z)/q(z), where p(z) and q(z) are complex polynomials. Then there is a finite number of open sets F1, …, Fr, that are left invariant by f(z) which, uh, is um… yay! Fractal Friday! The colors are so pretty!