[Eeglablist] More on memory, 64-bit Opteron

Gwen Alexandra Frishkoff sasha at cs.uoregon.edu
Thu Mar 24 11:14:09 PST 2005


Hi.

Would you explain the benefit of sampling >512hz for simultaneous
recordings with fMRI? Is it to allow better noise-signal separation?

Thank you,
Gwen F.

****************************
Gwen Alexandra ("Sasha") Frishkoff, Ph.D.
APA/IES Postdoctoral Fellow
Learning Research and Development Center
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University of Pittsburgh
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gwenf at pitt.edu OR sasha at cs.uoregon.edu
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On Thu, 24 Mar 2005, Arnaud Delorme wrote:

> Dear Jim,
>
> > Matlab has a limit on the size of an array or matrix because of the
> > memory address size. On 32 bit computers it was 2^31 (maybe 32). On
> > the 64-bit version, it's unfortunately still 2^31 for compatibility,
> > but you can now have multiple of those arrays/matrixes.
>
> I was able to reserve more than 3Gb in a single array (below) on the
> beta version of Matlab 64-bit for AMD Opteron computer (ours has 6Gb of
> RAM and is running Linux).
>
>   a     39000x10000           3120000000  double array
>
> On the web page below (which is more than 6-month old so it might
> already be outdated?), they mention that you should be able to create
> arrays of size up to 16Gb under Matlab 64-bit
>
> http://www.mathworks.com/access/helpdesk_beta/amd64/amd64_beta_rn.html
>
> About your sampling frequency (2048 Hz). Unless you want to perform
> simultaneous fMRI recordings, it is probably not necessary to sample at
> more than 512Hz.
>
> Arno
>


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