This sounds great and your changes with the API and dispatch are reassuring because I recently implemented something similar (for a totally unrelated package). A general question...
You wrote optimize(df, x0, BFGS()) I'm curious why you didn't make this optimize(df, x0, BFGS) Is there any performance difference between the two and why did you go with the former rather than the latter? Thanks for the update. Best regards, Eric
