[Eeglablist] Hardware recommendations

[Malte Anders]

Dear Makoto and Dear EEGLAB List,

I am still having trouble finding the right settings for ERSP.
My test data set is - for preprocessing - only highpass filtered at 1 Hz
(and a small amount of ASR).

I now call pop_newtimef() with the following settings:
Epoch -1 to 2 seconds as recommended
Cycles 3 0.5

In the first test, I set Frequency limits to [3 40] (or 'freqs', [3 40].
This gives me a good plot that shows ERSP roughly between 3 Hz and 40 Hz:
https://imgur.com/ldviMsZ
In the second test, the only thing I change is Frequency limits to [3 80]
(or 'freqs', [3 80]). The resulting plot cuts off quite a few amount of
data and only plots ERSP roughly between 6 Hz and 80 Hz:
https://imgur.com/sQnAqvD

I actually wanna see ERSP between 1 Hz and 80 Hz. However, the more I
increase the number of the highest frequency (e.g. 40 Hz to 80 Hz), the
more is cut off in the lower frequency range. I don't even get down to 1 Hz
with 'freqs', [3 40]. Setting  'freqs', [1 40] results in an error: Not
enough data points, reduce the window size or lowest frequency.
The bad thing is that I do need especially the lower frequencies (1 - 12 Hz
would be perfect) and the higher gamma frequencies between 40 and 80 Hz

I have dug into the available documentation, from my understanding setting
freqs to [3 40] and wavelet cycles to [3 0.5] should result in 1 Hz being
the lowest frequency analyzed, but in this case the plot is cut off at 3
Hz. Those are the settings: https://imgur.com/q8jcAss, resulting in the
picture above ( https://imgur.com/sQnAqvD ) where crucial info below 5-6 Hz
is simply cut off in the plot...

Anybody can shed some light onto what I need to change?

Thanks!

Malte

Am Mi., 15. Jan. 2020 um 20:14 Uhr schrieb Makoto Miyakoshi <
mmiyakoshi at ucsd.edu>:

> Dear Malte,
>
> Let me summarize our communication outside the list for others.
>
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>
> > CPU utilization is ~40% during the process, RAM utilization is 100% (so
> 100% of the 32 Gb are used)
>
> I suggest you try the following solution.
>
>    - Use the following optional inputs: 'cycles', [3 10], 'freqs', [1 45],
>    'nfreqs', [50], 'timesout', 6849 This should set your sliding window
> size
>    to 3380 ms or something like that, which should produce 6849 time point
>    i.e., about 1 time point per second.
>
> The most alarming sign was 'Using 3 cycles at lowest freq to 25600 at
> highest' 25600 cycles sounds crazy. If you use the above parameters, it
> will be up to 10.
>
> Makoto
>
> On Mon, Jan 13, 2020 at 11:20 PM Malte Anders <malteanders at gmail.com>
> wrote:
>
> > Hi everybody,
> >
> > I have collected huge amounts of EEG data with 512 Hz sampling frequency
> > and 34 electrodes.
> >
> > For one subject (~2-3 hours of data), a simple Time/Frequency
> decomposition
> > between 1 and 40 Hz with standard settings calling the newtimef function
> > takes approx. 8 hours for 1 hour of recorded data on my Computer (4790k,
> 32
> > Gb of DDR3 Ram, Intel HD GPU), so 16-24 hours for one dataset in total.
> > This is simply too long as I am currently working alone on this. CPU
> > utilization is ~40% during the process, RAM utilization is 100% (so 100%
> of
> > the 32 Gb are used).
> >
> > I would like to invest in new hardware (I am also considering used
> > hardware) with a price point around 1500-3000€. Which would make more
> > sense:
> > -A new Ryzen 3950x, 16 cores with 128 Gb of DDR4 RAM (2666 Mhz) ~ 1500€
> > -A used workstation, e.g. with Dual CPU: 2 x 12 core Xeon E52670v3 and
> 256
> > Gb RAM ~ used approx. 2200€
> >
> > The Xeon has more cores, but way lower clock speed. It does have double
> the
> > amount of RAM though.
> >
> > Would you recommend a dedicated GPU (Nvidia?) for this?
> >
> > Any recommendations are greatly appreciated. Thanks!
> > Malte
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-- 
Mit freundlichen Grüßen,

Malte Anders