Amy - The ITC phase coherence functions divide by the amplitude values, so /0 blows up. A more general approach might be to add a small bit of white noise to the data -- and investigate why the zeroes occur...<div><br></div>
<div>Scott Makeig<br><br><div class="gmail_quote">On Thu, May 26, 2011 at 11:23 AM, Amy Arlene Nash <span dir="ltr"><<a href="mailto:Amy.Nash@colorado.edu">Amy.Nash@colorado.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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<font face="Calibri, Verdana, Helvetica, Arial"><span style="font-size:11pt">Dear Arno -<br>
<br>
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 script’s inability to deal with zeroes in the data. The only workaround I’ve 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.<br>
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With thanks,<br><font color="#888888">
Amy</font><div><div></div><div class="h5"><br>
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On 5/25/11 11:23 PM, "Arnaud Delorme" <<a href="http://arno@ucsd.edu" target="_blank">arno@ucsd.edu</a>> wrote:<br>
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</div></div></span></font><div><div></div><div class="h5"><blockquote><font face="Calibri, Verdana, Helvetica, Arial"><span style="font-size:11pt">Dear Amy,<br>
<br>
I think the problem arises because you are trying to compute ERSP on continuous data. You need to extract data epochs first.<br>
Best,<br>
<br>
Arno<br>
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On May 5, 2011, at 2:34 PM, Amy Arlene Nash wrote:<br>
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</span></font><blockquote><font face="Calibri, Verdana, Helvetica, Arial"><span style="font-size:11pt">Thank you in advance for any help you all can offer with this question.<br>
<br>
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.<br>
<br>
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: ‘YLim’, Values must be increasing and non-NAN.<br>
<br>
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 haven’t been able to figure out why some files will analyze and plot and others won’t. 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.<br>
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Many thanks,<br>
Amy Nash<br>
<br>
Amy Nash, M.S., CCC-A<br>
Doctoral Candidate, University of Colorado at Boulder<br>
Brain and Behavior Laboratory<br>
<a href="tel:503-926-4919" value="+15039264919" target="_blank">503-926-4919</a> (cell) <br>
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