[Eeglablist] 0.01 Hz highpass filter isn't running

[Metin Özyağcılar]

Dear EEGLAB community,

I have recently tried to change the settings for my highpass filter that I
used to pre-process my data. I was using a 0.05Hz highpass filter, now
trying out 0.01 Hz, and I am using the function pop_eegfiltnew(). However,
when I tried to run the function, even after 10-20minutes I see no progress.

After doing some research and reading the manuals online, I’ve seen a
recommendation that for FIR filters a lower limit of about 0.1 is
recommendable and limits lower than that are not. I’ve additionally learned
that the lower and higher limits used in this function do not directly
correspond to the “cut-off” (e.g using 0.05, the “cut-off frequency” is set
to 0.025). All of these led me to have some questions:

1) Is there any way to still run 0.01 highpass filter with pop_eegfiltnew()
and if so how?
2) If I chose to run a 0.05 Hz highpass filter instead, would it be
appropriate to still set the lower limit as 0.05 but also report the
outcome of the function when writing the paper (i.e. transition band width:
0.05 Hz / passband edge(s): 0.05 Hz / cutoff frequency(ies) (-6 dB): 0.025
Hz / filtering the data; zero-phase, non-causal)? I feel not so confident
playing around with the parameters and the default settings of the function.
3) On an unrelated note: the filters are run very slow, even the 0.05Hz.
Does anyone else maybe have the same issue and if so how are you dealing
with it? I updated MATLAB, EEGLAB, even my operating system to the latest
version + freed up my storge but nothing has changed.

Any feedback would be highly appreciated. Thank you!

Best,
Metin