[FieldTrip] Question about ft_freqanalysis using wavelet method

"Jörn M. Horschig" jm.horschig at donders.ru.nl
Sat Jul 6 14:19:58 CEST 2013

Hi Szabi,

That error has nothing to do with the wavelet approach but with the fact 
that you want to have steps of 5ms (as specified in cfg.toi) for your 
TFR. FieldTrip will create one big data matrin nTrials x nChannels x 
nSamples x nFrequencies. With the settings you specified this will be 
quite huge, and it does not fit into memory when Matlab tries to 
initiate that variable. I would suggest you use 50ms steps, that is 
sufficient especially given that you need some tens of milliseconds for 
estimating the frequency content anyway. An alternative would be to use 
the torque/maui cluster at the Donders and request a session with loads 
of memory :)


On 7/5/2013 4:51 PM, Szabolcs Szebényi wrote:
> Dear Fieldtrip developers and users,
> I have a question about ft_freqanalysis when I use the 'wavelet' 
> method. When I call this fieldtrip function with the specifications 
> below, I get an error message right at the first trial:
> Error using zeros
> Out of memory. Type HELP MEMORY for your options.
> Error in ft_freqanalysis (line 601)
>         if powflg, powspctrm     = 
> nan+zeros(ntrials,nchan,nfoi,ntoi,cfg.precision);
>         end
> Here are my specifications:
>         cfg              = [];
>         cfg.trials       = find(data.trialinfo(:,3) == iPhase);
>         cfg.channel      = 'MEG';
>         cfg.method       = 'wavelet';
>         cfg.toi          = -1.5:0.005:4;
>         cfg.foi          = 30:1:90;
>         cfg.width        = 5;
>         cfg.keeptrials   = 'yes';
>         cfg.output       = 'pow';
>         cfg.pad          = 'maxperlen';
>         cfg.padtype      = 'zero';
>         cfg.polyremoval  = 0;
> I tried out the wavelet approach already for lower frequencies (foi = 
> 1:0.5:30; toi = -1.5:0.1:4; width = 7) and it worked fine for that. 
> For the higher frequencies above, it cannot proceed further to the 2nd 
> trial with 60GB memory either, so I think, the problem is somewhere else.
> The data itself consists of 275 trials, with a sampling rate of 600Hz; 
> 273 channels CTF MEG.
> I would highly appreciate if you could tell me where the problem is 
> and what I should change in order to proceed.
> Thank you in advance for your help,
> Szabolcs Szebényi
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> fieldtrip at donders.ru.nl
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Jörn M. Horschig
PhD Student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen
Neuronal Oscillations Group
FieldTrip Development Team

P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands

E-Mail: jm.horschig at donders.ru.nl
Tel:    +31-(0)24-36-68493
Web: http://www.ru.nl/donders

Visiting address:
Trigon, room 2.30
Kapittelweg 29
NL-6525 EN Nijmegen
The Netherlands

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