ENH: Allow to choose line-search parameters in related optimization algorithms

[paulestano]

Is your feature request related to a problem? Please describe.

While looking at #18481 I noticed it is not yet possible to choose c1 and/or c2 parameters of the line-search algorithm used within multiple optimization algorithms (CG, BFGS, NEWTON-CG) from the scipy.optimize.minimize API.

Describe the solution you'd like.

Add c1 and c2 parameters with default values to 1e-4 and 0.9 to the signature of _minimize_newtoncg, _minimize_cg and _minimize_bfgs .

Describe alternatives you've considered.

I am not mastering the whole scipy.optimize code base but I can't see any other straightforward one.

Additional context (e.g. screenshots, GIFs)

No response

[andyfaff]

This is already covered by #18977 for BFGS

[paulestano]

I was not aware of this PR. Is there any reason for not exposing c1 and c2 for other algorithms than BFGS?

[dschmitz89]

I don't think there are reasons against it. So far just no one looked into it.

Would you be interested in submitting a PR? #18977 can serve as a helpful example.