[Feature Request] Allow user to supply G2

[cpappenheimer]

Allow the user to supply MINUIT with an externally computed 2nd derivative of the gradient (e.g., with auto diff), in the same way that the user may specify the grad.

[HDembinski]

I'd like that as well, please report upstream at https://github.com/root-project/root

We are only wrapping Minuit2, which currently does not allow that.

Chances that someone will work on this is low, however. It is likely an invasive change to a difficult code base. You'd need to provide excellent value for someone to spend that time.

[cpappenheimer]

Reported upstream and received this reply: This is already possible in Minuit 2 by overriding FCNBase::G2() and HasG2(). This feature was implemented in 2022 by PR #11755. Since this feature is not documented yet, maybe you missed it and the way to address this GitHub issue is to improve the documentation.