Software for visualizing Julia sets I would like a program where I can enter any complex function and see its Julia set. I have not been able to find a web program which does this.  Most have functions which are of a fixed type, and you can only vary certain parameters.  
What software/online programs will allow me to view Julia set of whatever function I enter?
 A: First off, Julia sets are not defined for all complex functions. Even within the set of all functions where some notion of Julia set has been defined, the techniques used for one class of functions is likely different from the techniques used for another. For example, we might study polynomials, rational functions, entire functions, meromorphic functions, or perhaps other types. Thus, it makes sense that most software might focus on one type or another.
I've written some Javascript explorations of complex dynamics that you can find on my webspace. In particular, there is are links for both polynomials and rational functions. The functions are defined by entering lists of coefficients, so it's at least more general than playing with a parameter.
Of course, even within context of just quadratics, there are functions whose Julia sets are not computable and other Julia sets where a simple escape time algorithm requires more iterations than is feasible in a reasonable amount of time.
A: Software which lets the user enter the formula:


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