The Smath 'Genfit' is ½ robust compared to Mathcad.
Up until now, that's the only offer from the bakery.
This document shows the automatic iterative procedure.
The art under the hood is the initials. As a rule, there
is no rule about guessing the "initials". A rule that
works generally is trial/error to pass the manual
initials through two points of the data set.
You can recomfort yourself that some model are so
reactive that even Mathcad can not do.

Jean

Genfit Iterate.sm (43kb) downloaded 35 time(s).