<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Piotr,<div><br></div><div>this is most likely because some of your channels are linear combinations of other channels. The runica function will first compute the rank of the data matrix and reduce the dimensionality of it if necessary. </div><div><br></div><div>The rank of a common reference EEG data array is usually equal to the number of channel (minus 1 if the reference is listed in the data channels). There was a Matlab bug in the first versions of Matlab 7 on 64-bit machines that caused the rank function to return inaccurate results when using single precision float data. This is why we now forces the EEG data to be converted to double precision before running ICA (although the data will remain in single precision if not enough memory is available). It might be that you re not using the latest version of Matlab and EEGLAB.</div><div><br></div><div>Refer also to the following bug repports:</div><div><br></div><div><a href="https://sccn.ucsd.edu/eeglab/bugzilla/show_bug.cgi?id=317">https://sccn.ucsd.edu/eeglab/bugzilla/show_bug.cgi?id=317</a></div><div><br></div><div><a href="https://sccn.ucsd.edu/eeglab/bugzilla/show_bug.cgi?id=191">https://sccn.ucsd.edu/eeglab/bugzilla/show_bug.cgi?id=191</a></div><div><br></div><div><a href="https://sccn.ucsd.edu/eeglab/bugzilla/show_bug.cgi?id=187">https://sccn.ucsd.edu/eeglab/bugzilla/show_bug.cgi?id=187</a></div><div><br></div><div>Hope this helps,</div><div><br></div><div>A. Delorme</div><div><br><div><div>On Oct 13, 2009, at 6:22 AM, Piotr Jaskowski wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div lang="PL" link="blue" vlink="purple"><div class="Section1"><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; ">Dear All,<o:p></o:p></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span> <span class="Apple-converted-space"> </span></span><span lang="EN-US">I run ICA with 32-channel segmented data. I expected to get 32 ICA components. In fact, I’ve got only 22 components and a following message:<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US"><o:p> </o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">Input data size [22,51775] = 22 channels, 51775 frames/nAfter PCA dimension reduction,<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US"><span> <span class="Apple-converted-space"> </span></span>finding 22 ICA components using extended ICA.<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US"><o:p> </o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">Could anybody explain me where the remaining 10 components disappeared?<span class="Apple-converted-space"> </span><span> </span><o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US"><o:p> </o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">Best regards,<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">Piotr<o:p></o:p></span></div><div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span>---------------------------------------------------<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span>Prof. Piotr Jaskowski, Ph.D.<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">Department of Cognitive Psychology<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">University of Finance and Management<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span>Pawia 55, 01-030 Warszawa, Poland<o:p></o:p></span></div></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><span><a href="http://cogn.vizja.pl" style="color: blue; text-decoration: underline; ">http://cogn.vizja.pl</a><o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-bottom: 0.0001pt; margin-left: 0cm; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div></div><br><pre>
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