<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:arial,helvetica,sans-serif;font-size:10pt"><div>Dear Ingrid,<br><br>The analysis is painfully slow; it would need weeks to finish. Is there a MEX implementation of the time freq. analysis? Which is faster wltconvol or mtmconvol?<br>
Below is the configuration of the time freq. analysis.<br>
<br>
    cfg.sgn          = 'MEG';<br>
    cfg.method       = 'mtmconvol';    <br>
    cfg.output        = 'pow';<br>
    cfg.foi          = 40:2:100 ;<br>
    cfg.toi          = -1.4:0.01:1.4;<br>
    cfg.keeptrials='yes';<br>
    cfg.t_ftimwin    = ones(length(cfg.foi),1).*0.5;   % length of time window = 0.5 sec<br>
    cfg.taper        = 'hanning';   <br>
    TFR = freqanalysis(cfg, TFA_slo_fz);  <br><br>vs<br><br>    cfg.sgn          = 'MEG';<br>

    cfg.method       = 'wltconvol ';<br>

    cfg.width        = 7;<br>

    cfg.output        = 'pow';<br>

    cfg.foi          = 40:2:100 ;<br>

    cfg.toi          = -1.4:0.01:1.4;<br>

    cfg.keeptrials='yes';<br>

    TFR = freqanalysis(cfg, TFA_slo_fz);  <br>
<br>Data configuration:<br>Number of channels:151<br>
Sampling rate:250<br>
Number of trials:391<br><br>PC configuration: Windows Vista Business SP1 64 bit - Intel Core 2 CPU 6320 @ 1.86Ghz  1.86Ghz - RAM 4GB <br><br></div><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt;">Best regards,<br>Amr<br><br><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Ingrid Nieuwenhuis <ingrid.nieuwenhuis@DONDERS.RU.NL><br><b><span style="font-weight: bold;">To:</span></b> FIELDTRIP@NIC.SURFNET.NL<br><b><span style="font-weight: bold;">Sent:</span></b> Thursday, August 6, 2009 2:26:28 PM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [FIELDTRIP] freqanalysis_wltconvol variance<br></font><br>



 
 

 

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<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">Dear Amr,</span></font></p> 

<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">  </span></font></p> 

<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">If you do freqanalysis with cfg.keeptrials
= ‘yes’, you get the power per trial. If you subsequently use
freqdescriptives (see help for detailed options) you can compute the variance
over trials.</span></font></p> 

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<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">Best Ingrid</span></font></p> 

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<p class="MsoNormal"><b><font face="Tahoma" size="2"><span style="font-size: 10pt; font-family: Tahoma; font-weight: bold;">From:</span></font></b><font face="Tahoma" size="2"><span style="font-size: 10pt; font-family: Tahoma;">
 FieldTrip discussion list 
[mailto:FIELDTRIP@NIC.SURFNET.NL] <b><span style="font-weight: bold;">On Behalf
Of </span></b>Amr Ayoub<br>
<b><span style="font-weight: bold;">Sent:</span></b> Thursday, August 06, 2009
1:56 PM<br>
<b><span style="font-weight: bold;">To:</span></b> FIELDTRIP@NIC.SURFNET.NL<br>
<b><span style="font-weight: bold;">Subject:</span></b> [FIELDTRIP]
freqanalysis_wltconvol variance</span></font></p> 

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<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial;">Hello,<br>
<br>
I am expecting that you are averaging the power spectrum across the trials in
freqanalysis_wltconvol. Is there a way to compute the variance across the
number of trials?<br>
<br>
Thanks in advance<br>
Amr Ayoub</span></font></p> 

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<p>The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis.</p>
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