Mauro, Bruce, Peter,
3. Sometimes the fit have no-sense values so I have to save the project, rerun Artemis, and with the same parameters I obtain good fit. It seems like after a certain number of fits the software starts to fail.
This one I *have* seen. My current hypothesis is that I am using ifeffit's erase() command in a way that is flakey. Unfortunately, I haven't been able to come up with a simple enough demonstration of the problem to merit complaining to Matt about it. Indeed, I am not sure that erase() is really the problem. In any case, I changed how erase() is used in a few places in the version I am currently working on and haven't seen this problem recently. So, there is hope ;-) In the meantime, I don't have better advice than to save and restart.
I have also experienced the same problem when using "gifeffit", not artemis. Sometimes a "mutant" of this bug appears with the fit parameters staying okay, but the errors increasing with each fit attempt to enormous values. Unfortunately I also didn't find a cause -> effect relation until now.
For what it's worth, I agree that erase() seems to cause problems on some occassions, especially after multiple erase()'s and re-setting of arrays. I've also seen some odd problems using the slice() and interpolation functions in combination with the minimize() command. I have a hard time reproducing these problems myself, so they're difficult to diagnose. Sorry for the trouble!! --Matt