[Eeglablist] Slow ICA

[Kessler Memory Lab]

Dear EEGLAB users,
We've used ICA in our lab successfully in the past but recently came upon a
problem - some of our subjects's ICA take much longer than others. while
some take between 30-40 minutes, these may last up to 50+ hours.
I couldn't find a similar pattern in these subjects - some of them begin
with fixing rank computation inconsistency (64 to X), some start by
lowering learning rate and some begin training steps straight away.
Measuring was done using 64 electrodes + 5 external. Pre-process included
highpass over 0.01, and epochs were divided to [-1.2  1.8] sec windows.
Data was saved in double precision (.set + .fdt files)
I tried running on different computers, different versions of MATLAB, and
different methods (runica & binica) but still no change in speed.
One other thing, after pre-processing i noticed that when checking for th
rank (using rank(EEG.data(:,:)) the value is between 1-31, should it be 64?
Reducing PCA to 63 ('pca',63) dimensions also didn't help.
I read another thread with the same issue only I didn't quite get a
straight answer.
Any ideas on why this might happen?

Thank you,
Yair
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