[Eeglablist] FastICA failure in converge

[Klados Manousos]

Dear EEGLAB users,

I use FastICA v. 2.5 in EEG signals. My problem is that fastica does not
converge in 28 of my 54 datasets. When fastica stucks in one component, it
tries to converge five times (making 1000 iteration each time) and finaly it
appears me the following message.
*
Component number ##  did not converge in 1000 iterations.
Too many failures to converge (6). Giving up.
Adding the mean back to the data.*

I raised the number of interations to 10000 but then the algorithm becomes
very slow (so it loses it's fast ability) and in some datasets doesn't
converge again...

I would like to ask you why is that happening?

I read that *"The fastICA method failed completely to find the target
sources, since the Newton iteration always converged to one of the much
stronger confound sources."*  and that *"Even for very low signal strengths,
where the fastICA method fails to converge to the target sources"*
here<http://cds.ismrm.org/ismrm-2004/Files/000493.pdf>.
EEG signals have very low strength...so that is the answer to my previous
question or it's something more than EEG signal's strength?

Also i noticed that in the same dataset, fastica can converge ones and does
not converge other time...Is it that logical?

Thank you in advnace
Have a happy new year with my best wishes

Manousos


-- 
Klados A. Manousos
Graduate Student, Research Assistant
Group of Applied Neurosciences
Lab of Medical Informatics, Medical School
Aristotle University of Thessaloniki
Thessaloniki, Greece
_________________________________________________
Tel: +30-2310-999332
Website :
http://lomiweb.med.auth.gr/gan/index_en_files/Page609.htm
Blog: http://appliedneurosciences.blogspot.com
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