[Ifeffit] Random behaviour Artemis 0.7.001
Matt Newville
newville at cars.uchicago.edu
Wed Mar 17 09:35:13 CST 2004
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
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