Struve and related functions?

[gwater]

Struve and related functions?

[gwater]

Hmm, good question. I am asking myself a few questions when I think about scope: Could these functions benefit from sharing code (developer side)? Would users often use these functions side by side (user side)?

[heltonmc]

Yes - good questions!

Of course, these functions are rarely used so on the user side it would be hard for me to say but they are related with some code overlap. Looking at https://arxiv.org/pdf/2104.01700.pdf, Lommel, Anger-Weber, and Struve functions all share similar asymptotic expansions and the forms of the power series would be very similar. Of course these are all closely related to Bessel functions but I think these are better as a separate package as they are less used.

For developing, I'm not sure if these functions really require a different package if there is going to be any code overlap. I'd imagine even including all of these functions will be pretty lightweight. Though, would it be harder for users to find say Anger functions if they were under a package called Struve.jl?

I think my last point may be mute. There is some momentum to having SpecialFunctions.jl reexport native julia implementations so we can include a list of Special function libraries there which would help users identify which packages they need to use. Therefore, we can point them here for struve, lommel, anger, kelvin etc. But I do think defining a very specific scope for this package would be nice! SpecialFunctions.jl seems to struggle about not having a scope so noone knows what to include there.

I might suggest that this package includes

• Struve Functions
• Lommel
• Anger
• Weber
• Anger-Weber

Scorer functions could go in a separate package alongside airy functions. That kind of leaves Kelvin functions out on their own but they are so closely related to bessel functions it might be good to have them there (can have that discussion over at Bessels.jl)....

Edit: And of course including more functions here increases maintenance burden for you for a package that you may have wanted to be small. I'm of course happy to help maintain as well.