How do I check the number of start conditions in a `EnsembleProblem`

[TorkelE]

Say that I have created a

eoptprob =  Optimization.EnsembleProblem(opt_prob, u_inits)

how do i actually retrieve the number of starts encoded in it from eoptprob (I could use u_inits, but here I have passed eoptprob into another function where I do not have u_inits). It seems like there should be a simple way but

length(eoptprob)

throws an error and

eoptprob.u_init

is nothing.

[ChrisRackauckas]

• Document the general ensembles interface SciMLBase.jl#1001
• https://docs.sciml.ai/Optimization/dev/tutorials/ensemble/

I updated the ensemble docs and added general interface docs that cover the space quite well. This interface was then fully deprecated for the more general form that is used in all of the other solver packages, so using prob_func for the callback should just work.

[TorkelE]

Being able to use prob_func is a great help, thanks a lot!