[Eeglablist] Error message during time-frequency analysis

[Amy Arlene Nash]

Dear Arno -

Thanks so much for the time in responding.  However, I am already using
epoched files, not continuous data (.eeg is always epoched in Neuroscan ­ if
it were continuous, it would be a .cnt file).  The problem seems to center
upon the script¹s inability to deal with zeroes in the data.  The only
workaround I¹ve found so far (since writing earlier this month) is to add a
very small amount to the data to eliminate any possibility of zeroes (so
EEG.data=EEG.data+.00001 for example), and then it appears to analyze and
plot well.  Not ideal, but it is better than what I was dealing with before.

With thanks,
Amy


On 5/25/11 11:23 PM, "Arnaud Delorme" <arno at ucsd.edu> wrote:

> Dear Amy,
> 
> I think the problem arises because you are trying to compute ERSP on
> continuous data. You need to extract data epochs first.
> Best,
> 
> Arno
> 
> On May 5, 2011, at 2:34 PM, Amy Arlene Nash wrote:
> 
>> Thank you in advance for any help you all can offer with this question.
>> 
>> I have been running time-frequency analyses on a number of datasets which I
>> import from Neuroscan .eeg files.  Importing is no problem and most of the
>> time, I am able to get the analysis to run without issue, and lovely plots
>> are the result.  However, some of the time I get a warning about dividing by
>> zero, followed by a warning that the imaginary parts of complex X and/or Y
>> arguments are ignored.
>> 
>> Ultimately, the ERSP usually plots well, but the ITC is all dark blue, with
>> an error message that says: Bad property value found, Object name: axes,
>> Property name: ŒYLim¹, Values must be increasing and non-NAN.
>> 
>> Is there something I could change about my imported data files or analysis
>> parameters that would allow me to avoid this error?  These EEG recordings
>> were all acquired in the same way, and have similar properties overall... I
>> haven¹t been able to figure out why some files will analyze and plot and
>> others won¹t.  I apologize for my lack of general MATLAB troubleshooting
>> knowledge, and again, appreciate your input.  I would hate to lose some of my
>> sample to analysis errors like this.
>> 
>> Many thanks,
>> Amy Nash
>> 
>> Amy Nash, M.S., CCC-A
>> Doctoral Candidate, University of Colorado at Boulder
>> Brain and Behavior Laboratory
>> 503-926-4919 (cell)
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> 

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