[FieldTrip] ft_freqanalysis wavelet problem

[Silvia Formica]

Dear all,


I am new to fieldtrip so I apologize in advance if my question is trivial.

I am trying to run a time frequency analysis with Morlet wavelets.

Here is the code I am using:


cfg = [];
cfg.channel    = 1:64;
cfg.method     = 'wavelet';
cfg.pad        = 10;
cfg.width      = 7;
cfg.output     = 'pow';
cfg.foi        = 4:1:30;
cfg.toi        = 0:0.0039:2;    % my sampling rate is 512 Hz
TFRwave        = ft_freqanalysis(cfg, data_clean);


Where data_clean is the struct containing my trials. All my trials are the same length.

When I run this code, I get the following warning:

Warning: output time-bins are different from input time-bins
trial 1, frequency 26 (29.00 Hz)
Warning: output time-bins aretrial 2, frequency 25 (28.00 Hz)
Warning: output time-bins aretrial 3, frequency 24 (27.00 Hz)
Warning: output time-bins aretrial 4, frequency 25 (28.00 Hz)
Warning: output time-bins aretrial 5, frequency 23 (26.00 Hz)
[...]

I have no idea what this means. Any suggestion?

Despite the warning, the TRFwave is computed, but when I try to plot it I get a completely blue output. Here is the code I am using for the plot:

cfg = [];
cfg.baseline     = [-0.5 -0.1];
cfg.baselinetype = 'absolute';
cfg.zlim         = [-3e-27 3e-27];
cfg.showlabels   = 'yes';
cfg.layout       = 'biosemi64.lay';
figure
ft_multiplotTFR(cfg, TFRwave)


When I check the content of my TFRwave I can see it is not made of NaNs.
Is the problem due to the setting cfg.zlim? It is not clear to me how to set it.

Thanks in advance for any help!

Silvia



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