[Eeglablist] setting a common 'powbase'

[Toby Fernsler]

Hi Matt,
Baseline power is in units of Power, not amplitude. i.e. 
baseline_power=mean(abs(fft).^2), taken with regard to each frequency 
band, so each frequency has its own baseline power.
Hope That Helps,
Toby

Matt Valley wrote:
> Hello,
> I would like to use a common baseline for multiple ERSP calculations of 
> epoched
> single-channel data.  Specifically, i want to use the 2-sec baseline 
> region from
> one epoched dataset as the baseline for all my other epoched datasets.
>
> My attempts so far have been to produce a [new_powbase] matrix using the
> desired baseline waveform (it is automatically double and complex), and 
> then to enter
> 'powbase', [new_powbase], as an optional FFT/DFT parameter for all the 
> rest of my ersp calculations.
> Unfortunately this creates an error message saying that matlab cannot 
> plot imaginary numbers (unbelievable!).
>
> from the timef.m file, it looks like the paramater 'powbase' should be a 
> number,
> not a matrix name.
>
> if isnan(g.powbase)
>   myprintf(g.verbose,'\nComputing the mean baseline spectrum\n');
>   mbase = mean(P(:,baseln),2)';
> else
>   myprintf(g.verbose,'Using the input baseline spectrum\n');
>   mbase = g.powbase;
> end
>
> How can i make this 'powbase' value refer to the [new_powbase] matrix of 
> baseline
> ersp power that i have created?
>
> Thanks for your help
> Matt
>
>
> ---------------------
> Matt Valley
> Graduate Student, Firestein Lab
> Dept. Biological Sciences
> Columbia University
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