[FieldTrip] problem with ICA

Valentina Niccolai vale.niccolai at gmail.com
Fri Oct 5 18:30:02 CEST 2012


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.

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

I am thankful for any help.

Valentina Niccolai

    cfg.method       = 'runica';

    cfg.channel      = {'all','-EOG','-EMG'};

    comp = ft_componentanalysis(cfg, rej_vis_res);

The result of my component analysis looks like this:

comp =

      fsample: 600

         time: {1x237 cell}

        trial: {1x237 cell}

         topo: [306x2 double]

     unmixing: [2x306 double]

        label: {2x1 cell}

    topolabel: {306x1 cell}

         grad: [1x1 struct]

    trialinfo: [237x1 double]

          cfg: [1x1 struct]

and in comp.trial I get imaginary numbers:

>> comp.trial{1}

ans =

   1.0e-18 *

  Columns 1 through 6

   0.0127 - 0.0000i  -0.0339 + 0.0000i  -0.0203 + 0.0000i  -0.0269 -
0.0000i   0.0176 + 0.0000i  -0.0538 + 0.0000i

  -0.0069 - 0.0000i   0.0075 - 0.0000i   0.0097 - 0.0000i   0.0033 -
0.0000i   0.0214 - 0.0001i  -0.0031 - 0.0001i
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