<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">One typically gets the complex numbers from ICA when the data have less than full rank. For example, if there is a channel that is a flat line (maybe a bad channel or a reference) or when two channels are perfectly correlated (as when the data is mean mastoid referenced and one has included both mastoid channels as they will have a perfect -1 correlation).<div><br></div><div>Cheers!</div><div><br></div><div>Joe<br><div><br></div><div><br></div><div><br><div><div>On Oct 5, 2012, at 12:30 PM, Valentina Niccolai <<a href="mailto:vale.niccolai@gmail.com">vale.niccolai@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><p class="MsoNormal">Hallo.</p><p class="MsoNormal">I have a problem with the ICA, which I did not have before
with the same dataset. It seems not to work properly because it gives complex
numbers. The problem occurs also if I use older ft versions. I give in the ICA
the output of ft_rejectvisual (already preprocessed data), which looks normal
to me.</p><p class="MsoNormal">Here below is the output of ft_componentanalysis and in
attachment the strange output when calling ft_databrowser: some or all the
components are “dead” and the head views as well as the component number on the
top disappear.</p><p class="MsoNormal">I am thankful for any help.</p><div> <br class="webkit-block-placeholder"></div><p class="MsoNormal">Valentina Niccolai</p><div> <br class="webkit-block-placeholder"></div><p class="MsoNormal">
cfg.method = 'runica'; </p><p class="MsoNormal"> cfg.channel
= {'all','-EOG','-EMG'};</p><p class="MsoNormal"> comp = ft_componentanalysis(cfg,
rej_vis_res); </p><div> <br class="webkit-block-placeholder"></div><div> <br class="webkit-block-placeholder"></div><p class="MsoNormal">The result of my component analysis looks like this:</p><p class="MsoNormal">comp = </p><div> <br class="webkit-block-placeholder"></div><p class="MsoNormal"> fsample: 600</p><p class="MsoNormal"> time:
{1x237 cell}</p><p class="MsoNormal"> trial: {1x237
cell}</p><p class="MsoNormal"> topo:
[306x2 double]</p><p class="MsoNormal"> unmixing: [2x306 double]</p><p class="MsoNormal"> label: {2x1 cell}</p><p class="MsoNormal"> topolabel: {306x1 cell}</p><p class="MsoNormal"> grad: [1x1
struct]</p><p class="MsoNormal"> trialinfo: [237x1 double]</p><p class="MsoNormal"> cfg:
[1x1 struct]</p><div> <br class="webkit-block-placeholder"></div><p class="MsoNormal">and in comp.trial I get imaginary numbers:</p><div> <br class="webkit-block-placeholder"></div><p class="MsoNormal">>> comp.trial{1}</p><p class="MsoNormal">ans =</p><p class="MsoNormal"> 1.0e-18 *</p><p class="MsoNormal"> Columns 1 through 6</p><p class="MsoNormal"> 0.0127 - 0.0000i -0.0339 + 0.0000i
-0.0203 + 0.0000i -0.0269 - 0.0000i 0.0176 + 0.0000i
-0.0538 + 0.0000i</p><p class="MsoNormal"> -0.0069 - 0.0000i 0.0075 -
0.0000i 0.0097 - 0.0000i 0.0033 - 0.0000i
0.0214 - 0.0001i -0.0031 - 0.0001i</p><div> <br class="webkit-block-placeholder"></div>
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