[Eeglablist] what is the difference between eegfilt and eegfiltfft

[Makoto Miyakoshi]

Dear QuietWaterDeepFlow,

Do not apply high-pass filter on the epoched data. Always go back to the
continuous data and apply it. Every filter has time constant (filter order)
which is like a sliding window. If you have a boundary on your data, the
filtering process terminates the process before it and resumes after it.
You don't want to have it happen too many times, because near the boundary
data are not properly filtered.

Makoto

On Sat, Feb 7, 2015 at 12:19 AM, 静水深流 <123975520 at qq.com> wrote:

> Hi,
>
> I encountered a problem when filtering the epoched data (the frame per
> epoch is 2000 and the sample rate is 500 Hz) with a highpass of 2 Hz. It
> was ok to use the eegfiltfft(data, 500, 2, []), but was wrong to use the
> eegfilt(data, 500, 2, []). However, It was ok to use the eegfilt(data,
> 500, 3, []). I am wondering why cannot filter the data with a highpass of
> < 3 Hz. Moreover, what the difference between eegfiltfft and eegfilt?
> Thanks.
>
> Regards
> Ya
>
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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