[Eeglablist] A non-EEGLAB question: What to do with small eigenvalues when performing data whitening in EEG artifact removal.

[Makoto Miyakoshi]

Dear Reza,

> But I don't one to compress my data at this point because I want to have
the same number of signals after artifact removal.

I would say this motivation is wrong. You should count the rank of the
data, not the number of the channels. What if your data are severely rank
deficient due to channel bridging etc? You don't want to let your ICA fail
in that way.

Makoto



On Fri, Oct 28, 2016 at 2:26 AM, Seyed Mohammad Reza Shahshahni <
smr.shahshahani at gmail.com> wrote:

> Dear all
>
> I'm trying to implement on-line artifact removal based on ICA. As known,
> in and ICA algorithm like FastICA or SOBI we need to perform data whitening
> to lessen the complexity.
> I have encountered a case where some eigenvalues I have computed are very
> small (in order of 1e-7) which are literally zeros. How should I deal with
> them. I know one solution is do as in PCA. But I don't one to compress my
> data at this point because I want to have the same number of signals after
> artifact removal.
>
> Any suggestions?
>
> Thanks,
>
> Regards,
> Reza M. Shahshahani
> PhD Candidate of Electical Engineering,
> Shahid Beheshti University,
> Tehran,Iran.
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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