[FieldTrip] error with runica

[Lozano Soldevilla, D. (Diego)]

Hi Phyllis, This error occurs when the input data is rank deficient, see: http://fieldtrip.fcdonders.nl/faq/why_does_my_ica_output_contain_complex_numbers Try to exclude the reference channel of your EEG (which is a linear combination of other EEG channels and can produce the rank deficiency) or ask runinca N independent components being N the rank of your data best, Diego ----- Original Message -----
> From: "Phyllis Mania" <phyllis.mania at uni-hamburg.de>
> To: fieldtrip at science.ru.nl
> Sent: Wednesday, 16 October, 2013 6:09:03 PM
> Subject: [FieldTrip] error with runica
> Dear all,
> I have a problem with running an ICA in one of my subjects (EEG, 70
> channels, 878 trials), even though it was preprocessed exactly like
> all others (same number of channels, similar number of trials). When
> calling ft_componentanalysis with ‘runica’ the learning rate gets as
> low as 3.09032e-05 before it actually starts with step 1. It takes up
> to 512 steps (very slowly) but the lrate never changes from 0 after
> the first few steps while the angledelta is constant at 22.3.
> In the the end I get the following warning:
> Warning: Matrix is close to singular or badly scaled. Results may be
> inaccurate. RCOND = 1.190323e-16.
> > In runica at 1430
> In ft_componentanalysis at 463
> When trying to plot the components with ft_topoplotTFR only one black
> & white head shows up and the following error:
> Error using surf (line 75)
> X, Y, Z, and C cannot be complex.
> Error in ft_plot_topo (line 251)
> h = surf(Xi-deltax/2,Yi-deltay/2,zeros(size(Zi)), Zi, 'EdgeColor',
> 'none', 'FaceColor', shading);
> Error in topoplot_common (line 704)
> ft_plot_topo(chanX,chanY,datavector,'interpmethod',cfg.interpolation,...
> Error in ft_topoplotTFR (line 185)
> [cfg] = topoplot_common(cfg, varargin{:});
> Error in ft_topoplotIC (line 148)
> ft_topoplotTFR(cfg, varargin{:});
> Running ‘fastica’ seems to work fine. I read about the issue with some
> 64 bit computers but the workaround with pop_runica didn’t work for
> me.
> Thank you in advance!
> Best,
> Phyllis
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-- PhD Student Neuronal Oscillations Group Donders Institute for Brain, Cognition and Behaviour Centre for Cognitive Neuroimaging Radboud University Nijmegen NL-6525 EN Nijmegen The Netherlands http://www.ru.nl/people/donders/lozano-soldevilla-d/
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