too many trials

Sameer Walawalkar sameer at ANDREW.CMU.EDU
Sun Feb 18 16:53:01 CET 2007

thanks Robert,

I managed to do ICA for the data, but runica, fastica and jader gave
errors.  Varimax finally worked.

??? Error using ==> zeros
Product of dimensions is greater than maximum integer.

Error in ==> jader at 90
CM 		= zeros(m,m*nbcm);  % Storage for cumulant matrices

Error in ==> componentanalysis at 323
       weights = jader(dat);

Calculating covariance...
??? Error using ==> componentanalysis
call to fastica failed

step 60 - lrate 0.000000, wchange 69.06649297, angledelta 99.6 deg
runica(): QUITTING - weight matrix may not be invertible!
??? Error using ==> mtimes
Inner matrix dimensions must agree.

Error in ==> componentanalysis at 394
     comp.trial{trial} = weights * sphere * data.trial{trial};

Do these errors tell you anything about the data?

Finally, I really need to know (do I) about the .lay file to be used for
neuromag 306 data to see the independent components. I have asked about
this two or three times in earlier emails.


On Sun, 18 Feb 2007, Robert Oostenveld wrote:

> Hi Sameer,
> On 16 Feb 2007, at 18:12, Sameer Walawalkar wrote:
>> I am close to fixing the problem with too many trials, principaly by
>> writing another function which takes the cfg output from definetrial,
>> discards the trial definitions in cfg.trl and replaces it with the correct
>> set based on my reading the trigger channel.
> What you have done is that you have created your own 'trialfun'. That is
> perfectly acceptable, and actually FT is explicitely designed to support
> that. See also
> id=fieldtrip:documentation:tutorial:preprocessing at the bottom for an
> example. Another example is at
> id=fieldtrip:documentation:detect_the_muscle_activity_in_an_emg_channel_
> and_use_that_as_trial_definition
> In custom trialfuns, people can use whatever they want to make the "trl"
> structure, and use read_fcdc_event of they wish or not.
> You can still use definetrial by
>  cfg.trialfun = 'your_function'
> Actually the default is
>  cfg.trialfun = 'trialfun_general'
> and trialfun_general is using the data-independent read_fcdc_event. Feel free
> to add your trialfun to the example matlab scripts section on the
> documentation wiki.
>> But I have left cfg.event untouched.
>> My question is, for the proper working of DICS (and other processing) once
>> the trials have been defined, do I have to make any changes to cfg.event at
>> all or I could proceed.
> cfg.event is only stored for later reference by yourself. Other FT functions
> (except for "recodeevent", which is not included in the ftp version sofar) do
> not use it.
> Robert

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