[Eeglablist] Re: [PMX:####] Having memory size problems, how do people handle this?

Schloegl Alois alois.schloegl at tugraz.at
Sat Jan 15 03:16:46 PST 2005

> Jim Kroger wrote:
>> Hi, we're trying to analyze EEG data collected with a Biosemi 128
>> channel system. Some of our data files are around 3 gigabytes. We
>> started with Windows and Matlab, but have since purchased the newest
>> Suse for our Dual Opteron IBM Intellistation APro and have installed
>> 64 bit Matlab and EEGLAB. Still, today when we tried to load a 2 gig
>> file, we got a Matlab out of memory error. When we installed Suse, we
>> allocated 7 gigs to it, and we made a 2 gig swap partition. We presume
>> we have it things set up so that it uses the swap partition as desired
>> (??). We have one gig of ram for each processor; as I understand it,
>> the machine shares these so that the processor we are effectively
>> using to run Matlab has 2 gigs available.
>> Where do we need to tackle this problem? Should we increase swap? Is
>> our problem too little RAM? Is it just impossible to work with files
>> above a certain size?  If the latter, how do you Biosemi users
>> approach this problem?
>> Many thanks for any info,
>> Jim

Dear Jim,

you can use SOPEN, SREAD, SCLOSE from BIOSIG to read only part of the data.
HDR = SOPEN(filename, CHAN) allows you to select channels,
SREAD(HDR,number_of_seconds,startposition) allows you to read segments 
of data.
The functions are implemented in such a way that only the required data is

BIOSIG is already included in the latest EEGLAB version or you can 
download the
latest version for BIOSIG from http://biosig.sf.net/

I hope this helps

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