problem on wavelet analysis, combine channel

Christian Hesse c.hesse at FCDONDERS.RU.NL
Fri Mar 30 17:22:54 CEST 2007


Hi Eve,

just to chip in here: what (in simple terms) do you want to achieve
using wavelet analysis of your data? What do you ultimately want to
plot?

Christian




On 30 Mar 2007, at 15:49, alotof eve wrote:

> Dear Jan and Nathan,
>
>     Thank you so much. But I am 80 percent sure it's not a common
> memory problem. My computer is 1GB of RAM. And if I don't use
> combination, I can select very fine parameters for wavelet
> analysis. My data is neuromag .fif data. I suppose something wrong
> with the channel counting.
>     Thanks.
>
> Best,
> eve
>
> Jan Mathijs Schoffelen <Jan.Schoffelen at FCDONDERS.RU.NL> wrote:
> Dear Eve,
>
> I totally agree with Nathan. Specifying (unintended, but
> still... ;o) )
> 'powandcsd', in particular in combination with a spectro-temporal
> reconstruction really blows up your memory requirements. Especially
> when
> (again probably unintended) you are computing csd's for all
> channelcombination. I'll leave it up to you to calculate how many
> bytes are
> needed only to represent your output csd-matrix in memory.
> Some hints:
> -each double precision number requires 8 bytes of memory in matlab
> -each complex number consists of two double precision numbers
> -(numberoftrials)x(numberofchannelcombinations)x
> (numberoffrequencypoints)x
> (numberoftimepoints) can become really big.
>
> Yours,
>
> Jan-Mathijs
>
> -----Original Message-----
> From: FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL]
> On Behalf
> Of Nathan Weisz
> Sent: Friday, March 30, 2007 9:31 AM
> To: FIELDTRIP at NIC.SURFNET.NL
> Subject: Re: [FIELDTRIP] problem on wavelet analysis, combine channel
>
> hi eve,
>
> i'm not too familiar with the fieldtrip specifications, but:
>
> > Out of memory. Type HELP MEMORY for your options.
>
> do you have enough RAM?
>
> this would then not be a real fieldtrip problem, but a rather common
> problem generally when using matlab.
>
> good luck!
>
> nathan
>
>
> Expecting? Get great news right away with email Auto-Check.
> Try the Yahoo! Mail Beta.

----------------------------------------------------------------------
Christian Hesse, PhD, MIEEE

F.C. Donders Centre for Cognitive Neuroimaging
P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands

Tel.: +31 (0)24 36 68293
Fax: +31 (0)24 36 10989

Email: c.hesse at fcdonders.ru.nl
Web: www.fcdonders.ru.nl
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