[FieldTrip] importing large edf data

[Leila Ayoubian]

Hi:Thanks for providing us with this amazing toolbox.
I am new to fieldtrip. I am trying to import EEG data in the format of *.edf for the purpose of seizure detection for epileptic patients. I can't break up the data as you understand the detection has to have continuous data. However I could load section of the data at a time and clear what is already used and reload again. 
So trying to load the data like this:
cfg.dataset= ('mydata.edf');
rawdata=ft_preprocessing(cfg);
This is the error message I get :
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error using zeros
Requested 51x51927040 (19.7GB) array exceeds maximum array size preference. Creation of arrays greater than this limit may take a long time
and cause MATLAB to become unresponsive. See array size limit or preference panel for more information.

Error in read_edf (line 403)
  dat = zeros(length(chanindx),nepochs*epochlength);

Error in ft_read_data (line 622)
    dat = read_edf(filename, hdr, begsample, endsample, chanindx);

Error in ft_preprocessing (line 566)
      dat = ft_read_data(cfg.datafile, 'header', hdr, 'begsample', begsample, 'endsample', endsample, 'chanindx', rawindx, 'checkboundary',
      strcmp(cfg.continuous, 'no'), 'dataformat', cfg.dataformat);

Error in ReadFedfiles (line 8)
rawdata=ft_preprocessing(cfg);%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
I tried the ft_redefinetrial, but since the input to this file is the output from ft-PREPROCESSING it gives me the same error. 


I also tried to use ft_read_data to choose the samples I want to load : filename     = 'mydata.edf'
 hdr   = ft_read_header(filename);
 sample.start=1
 sample.end=100
dat = ft_read_data(filename,'sample.start','1','sample.end','100') 
and here is again the error message:
Error using zeros
Requested 51x51927040 (19.7GB) array exceeds maximum array size preference. Creation of arrays greater than this limit may take a
long time and cause MATLAB to become unresponsive. See array size limit or preference panel for more information.

Error in read_edf (line 403)
  dat = zeros(length(chanindx),nepochs*epochlength);

Error in ft_read_data (line 622)
    dat = read_edf(filename, hdr, begsample, endsample, chanindx);

Error in ReadFedfiles (line 31)
dat = ft_read_data(filename,'sample.start','1','sample.end','100')
 
>> 

Could you please direct me as to which functions and in which order I should be using the functions to load data in smaller samples.Some examples would be useful.
Thanks again for your support and assistance. 
We appreciate your effort.
Kind regards

___________________________________________________ Dr. Leila Ayoubian 
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