Support for Bessel functions (or SpecialFunctions.jl in general)

[merlinpelz]

It seems there is no ::Interval support for besselk and besseli of SpecialFunctions.jl since IntervalRootFinding.roots() gives a StackOverflowError when applied to (a combination of) these functions. This issue may be relevant for both IntervalArithmetic and IntervalRootFinding.

[dpsanders]

Yes, unfortunately implementing interval versions of special functions is Non-trivial.

However, many such functions are implemented in arb, so I think we should just wrap those.

[merlinpelz]

That would be highly appreciated - since the performance of IntervalRootFinding is so strong for "normal" functions and Bessel functions appear often in boundary value problems.

[wsshin]

I am suffering from this exact issue as well. It will be very nice to be able to find the roots of special functions by IntervalRootFinding.jl.