[Eeglablist] The number of the ICA components is smaller than the number of channels.

[hui zhang]

Hi David,

Thank you. But my data does have 66 channels, and I am interested in 2:63.
And for different data sets, the output of detected channel number is
different.

After high pass filter, it became normal. Anyone here can explain this?

On Wed, Mar 9, 2011 at 6:55 AM, David Post <djp227 at cornell.edu> wrote:

> Hello Hui,
>
> I believe the problem you are experiencing is due to the fact that your
> data has 39 channels, and in your code you use the option 'chanind' and set
> the channels to 2:63.  You might fix your problem by instead using the
> command:
>
> *EEG = pop_runica(EEG, 'icatype', 'runica', 'chanind', 1:39, 'extended',
> 1);*
>
> Regards,
> David
>
>
>
> On Tue, Mar 8, 2011 at 5:02 PM, Arnaud Delorme <arno at ucsd.edu> wrote:
>
>> Dear Hui,
>>
>> as the warning says, this is probably due to some problem with Matlab when
>> computing the rank of your Matrix. You should upgrade to a newer Matlab
>> version and this should be fine.
>>
>> Best regards,
>>
>> Arno
>>
>> On Feb 4, 2011, at 12:39 PM, hui zhang wrote:
>>
>> Hi,
>>
>> When using the function of pop_runica to run ica on epoched data, I got
>> the following message:
>> *
>> Attempting to convert data matrix to double precision for more accurate
>> ICA results.
>> Warning: fixing rank computation inconsistency (39 vs 38) most likely
>> because running under Linux 64-bit MatlabData rank (39) is smaller than the
>> number of channels (62).
>>
>> Input data size [39,654000] = 39 channels, 654000 frames/nAfter PCA
>> dimension reduction,
>>   finding 39 ICA components using extended ICA.*
>>
>> The matlab code:
>> *eeglab;
>> EEG = pop_loadset('filename',filename);
>> EEG = pop_runica(EEG, 'icatype', 'runica', 'chanind',[2:63], 'extended',
>> 1);*
>>
>> I ran this code on datasets of previous project, it seems fine.
>> The version of eeglab installed on my computer is: eeglab9.0.1.2b.
>>
>> Does anyone have any idea on this? Is there any ways I can turn the pca
>> off in my code?
>>
>> Thanks in advance!
>>
>> -Hui
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