RFC: add `@stdlib/stats/base/dists/generalized-hyperbolic/mean`

[Planeshifter]

Description

This RFC proposes implementing the mean for the Generalized Hyperbolic distribution as package @stdlib/stats/base/dists/generalized-hyperbolic/mean.

Related Issues

Parent: #5486

Questions

No.

Other

Implementation notes:

• Follow existing stdlib patterns for implementations of the various statistical distributions. See the existing distribution implementations for guidance.

Checklist

• I have read and understood the Code of Conduct.
• Searched for existing issues and pull requests.
• The issue name begins with RFC:.

[saurabhraghuvanshii]

I am working on this.

[Planeshifter]

@saurabhraghuvanshii Per definition of the mean on Wikipedia, we probably need the modified Bessel function of the second kind of any real-valued order (see SciPy to implement this, which we currently do not have as a special function.

Marking this as blocked until we have the pre-requisites ready.