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<div class="moz-cite-prefix">Although I am not an expert in
connectivity analysis, but from a mathematical point of view it
looks like the case where at least one variable in covariance
matrix is a exact linear combination of other and hence it is not
positive definite.<br>
This could be due to rejection of few components by ICA ? Other
experts may shed more light...<br>
<br>
<br>
On 22/04/2013 21:36, Martin Winkels wrote:<br>
</div>
<blockquote
cite="mid:CAHDG_rUoTP-UA1Sy0opwLDuzT7OAAxssbsXx9pN5Ydw5Hbi_nQ@mail.gmail.com"
type="cite">
<div dir="ltr">Hello Guys,<br>
<div class="gmail_quote">
<div dir="ltr">
<div>
<div><br>
</div>
<div>I am trying to perform connectivity analysis in
sensor domain (fieldtrip and matlab are up to date).
Within doing that I am facing a small problem in the ICA
analysis in combination with a MVAR analysis. If I
execute the following code, I get an error message as
follows:<br>
<br>
<br>
</div>
Error using chol<br>
Matrix must be positive definite.<br>
<br>
Error in armorf (line 40)<br>
ap(:,:,1) = inv((chol(ap(:,:,1)/Nr*(Nl-1)))');<br>
<br>
Error in ft_mvaranalysis (line 390)<br>
[ar, tmpnoisecov] = armorf(dat,
numel(rpt{rlop}), size(tmpdata.trial{1},2), cfg.order);<br>
<br>
Error in mu_firstexample (line 90)<br>
mdata = ft_mvaranalysis(cfg, data_ma_ica);<br>
<br>
<br>
</div>
Can anybody help me with that issue?<br>
<div>
<div><br>
<div><br>
% artifact correction: ica component analysis <br>
<br>
cfg = [];<br>
cfg.method = 'runica'; <br>
cfg.runica.pca = 40;<br>
comp = ft_componentanalysis(cfg, data_ma);<br>
<br>
cfg = [];<br>
cfg.layout = 'CTF275.lay';<br>
cfg.viewmode = 'component';<br>
ft_databrowser(cfg, comp)<br>
<br>
%% artifact correction: ica component rejection<br>
<br>
cfg = [];<br>
cfg.component = [4]; % to be removed component(s)<br>
data_ma_ica = ft_rejectcomponent(cfg, comp,
data_ma);<br>
<br>
%% compute MVAR, spectral transfer and granger<br>
<br>
% mvar<br>
cfg = [];<br>
cfg.order = 5;<br>
cfg.toolbox = 'bsmart';<br>
<br>
mdata = ft_mvaranalysis(cfg, data_ma_ica);<br>
<br>
<br>
</div>
<div>Thank you,<br clear="all">
</div>
<div><br>
-- <br>
Martin Winkels<br>
<br>
B.Sc. / Ingenieur in
<div>
Medizininformatik und Biomedizintechnik
<div>
<br>
University of Münster<br>
<br>
phone: <a moz-do-not-send="true"
href="tel:%2B49%20177%206090603"
value="+491776090603" target="_blank">+49 177
6090603</a><br>
mail: <a moz-do-not-send="true"
href="mailto:m_wink10@uni-muenster.de"
target="_blank">m_wink10@uni-muenster.de</a></div>
</div>
</div>
</div>
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</div>
<br>
</div>
<br>
</div>
<br>
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</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
With Best Regards,
Narayan P Subramaniyam, M.Sc.
Researcher/PhD student
Department of Electronics and Communications Engineering
Tampere University of Technology
Finn-Medi 1, 4th Floor, Room 203
Biokatu 6, FI-33520 Tampere, Finland
Tel: +358 (0)40 198 1951
E-mail: <a class="moz-txt-link-abbreviated" href="mailto:narayan.ps@tut.fi">narayan.ps@tut.fi</a>
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