[Feature] Support external julia libraries for custom operators

Is your feature request related to a problem? Please describe. I’d like to use a bessel function as a custom binary operator with PySR. It seems that I need to use an external library like SpecialFunctions.jl. However, I can not seem to figure out an easy way to use a library function with binary_operators argument. Everything I’ve tried so far ended up in JULIA: AssertionError: Your configuration is invalid - one of your operators (besselj) is not well-defined over the real line., although I assume this means a compile rather then mathematical issue underneath.

Describe the solution you’d like A custom parameter with library names to additionally load passed to PySRRegressor could probably be doable?

Additional context I’m not a Julia user, so I might be missing something trivial.

[MilesCranmer]

Awesome; will add it.

Happy to hear you are enjoying the package! No need for the tip, but thanks for the offer – be sure to spread the word about PySR though 😃 (Although if we meet in person I will gladly take you up on a beer!)

[EvilMav]

Wow, thank you for the fast response and all the work! This should do the trick =)

As a side note, I think I should just make all the SpecialFunctions.jl functions available by default in PySR, since it has a lot of useful functions. What do you think?

I agree =)

PS I’d be happy to buy you a beer for this amazing project - feel free to drop me a link if you wish.