[Eeglablist] Out of memory

[Matthew Zivot]

I've been having similar memory problems importing EGI raw files.  As  
a fix, I'm playing around with the pop_readsegegi function.  It calls  
the readegi function, which reads the eeg data in as doubles, in which  
each number require 8 bytes of storage.  I have converted these to  
int8 (for the event data) which requires 1 byte and int16 (for the eeg  
data) which requires 2 bytes.  Considering the amount of data points,  
this greatly decreases the memory usage.

int8 storage can only integers from -128 to 127 but I believe that the  
event channel is only zeros and ones.  int16 storage can only hold  
integers from -32,768 to 32,767 but I believe that the eeg data is  
exclusively integers and there is no value close to 32,767 in my data.

I am not well versed in EEG analysis.  Can anyone see problems with  
this approach?

Thank you,
Matthew Zivot

Quoting Arnaud Delorme <arno at ucsd.edu>:

> Dear Alexandre,
>
> increasing virtual or swap memory will most likely not help because  
> Matlab only seems to be able to allocate real physical non-paged  
> memory.
>
> The most affected operating system seems to be Windows 32-bit with  
> recent versions of Matlab where even with more than 2Gb physical  
> memory, it is sometimes impossible to open 100Mb files.
>
> The solutions are
> - buy even more RAM
> - Close all programs, remove Windows services (Adobe etc?), reboot
> - Change of OS (Windows 7 might seems to have less problems than Win XP)
> - Try different memory manager ?start Matlab from the DOS command  
> line with matlab ?memmgr fast option
> - Use older versions of Matlab that behave better with 32-bit  
> systems (how old?)
> - Look at http://www.mathworks.com/support/tech-notes/1100/1107.html
>
> Under OSx or linux, Matlab cannot allocated inactive memory. You may  
> free it by tiping "du -sx /" (in OSx you will see the blue inactive  
> memory decreasing).
>
> Arno
>
> ps: under Matlab 2010b Linux Fedora Core 64-bit, we have  
> successfully allocated matrices of up to 74Gb.
>
> On Nov 13, 2010, at 9:23 PM, Alexandre Lehmann wrote:
>
>> Hello All,
>>
>> Klados, when you say "Try to swap your physical memory from the  
>> hard drive.", you mean adding some pagfile in memory preferences in  
>> windows ? Or are you refering to another procedure or another OS ?
>>
>> I did try to increase my virtual memory by creating a pagefile of  
>> 4Gb, but even 150Mb bdf files would still give an out of memory  
>> error.
>>
>> Thanks,
>>
>> Regards
>>
>> Alexandre
>>
>>
>>
>> On Thu, Nov 11, 2010 at 2:21 AM, Klados Manousos  
>> <mklados at med.auth.gr> wrote:
>> Hello to all,
>>
>> Both systems you menioned are running the same programes? Because  
>> one system may run in background applications that need more memory  
>> than the other....
>>
>> Try to swap your physical memory from the hard drive... With that  
>> way i achieved to load big files in EEGLAB
>>
>> 2010/11/9 Benjamin Kuhr <bkuhr at uni-osnabrueck.de>
>>
>> Hi,
>>
>> I tried to import a large *.bdf file, 614 MB. I get the "Out of memory" -
>> message, but not on all computers and for some reason it seems as it does
>> not depend on the actual memory. It works on a weaker system, but not on
>> the current one, which has 3.8 GiB of memory and a Intel Core 2 Duo CPU
>> R7500 @ 2.93 GHz.
>>
>> Even on identical systems with the same hardware and same software I can
>> load the file only on one of them. I tired it with Windows XP and Ubuntu
>> 10 on the system mentioned above, no difference. Any suggestions?
>>
>> Thanks in advance
>> Benjamin Kuhr
>>
>>
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>>
>>
>> --
>> Manousos A. Klados
>> PhD Candidate -- Research Assistant
>> Group of Applied Neurosciences
>> Lab of Medical Informatics
>> School of Medicine
>> Aristotle University of Thessaloniki
>> P.O. Box 323 54124 Thessaloniki Greece
>> _________________________________________________
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>> Fax:+30-2310-999263
>> Website: http://lomiweb.med.auth.gr/gan/mklados
>>
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