Allowing xtol and ftol stopping criteria in OptimisationController

[MichaelClerx]

Closes #1502

• ftol is already possible, using set_max_unchanged_iterations(1, ftol)
• xtol can now similarly be implemented with set_max_unmoved_iterations(1, xtol)
• Moved part of stopping criteria code out of run(), as per Refactor MCMCController.run() and OptimiserController.run() #919

[MichaelClerx]

@martinjrobins @chonlei @mirams can you have a look and see if this makes sense, before I add tests?

[mirams]

"unmoved/unchanged" is a bit vague and not immediately obvious to me in terms of whether it refers to xtol or ftol? unmoved parameters, unchanged objective?

[MichaelClerx]

I agree! But can't think of anything better that doesn't involve deprecating set_max_unchanged_iterations which is probably one of the most used methods of the controller class

[mirams]

Hmmmm, given all the different names that exist already, inventing another set that are pints specific doesn't seem great anyway - and even more so if they are vague!

[MichaelClerx]

Fine, we can just go with long names

• set_max_unchanged_function_iterations
• set_max_unchanged_parameter_iterations
• Make "unchanged_iterations" be a deprecated alias of unchanged_function_iterations

[MichaelClerx]

Fine, we can just go with long names

* [ ]  set_max_unchanged_function_iterations

* [ ]  set_max_unchanged_parameter_iterations

* [ ]  Make "unchanged_iterations" be a deprecated alias of unchanged_function_iterations

Going to do this next week, merge it in, and do a new release that's compatible with latest numpy #1712 unless anyone has strong objections @mirams @martinjrobins @chonlei ?