Hi Experts:

I analyzed the data collected in my lab following the tutorial of SPM for fNIRS toolbox. I encountered a problem when I perform the temporal analysis.

My data is large (~100,000 time points in raw data). I followed exactly the same parameter settings as the tutorial, especially I intended to downsample it to 1 Hz. However, during the execution of temporal analysis, an error was printed on the screen:

---------------------------------------------------------
Apply temporal filters to fNIRS data...
---------------------------------------------------------
Read and display time series of fNIRS data...
Specify parameters for temporal preprocessing...
Completed.

Apply a temporal filter to hemoglobin changes...
Error using filter_with_correction (line 51)
Calculated filter coefficients have poles on or outside the unit circle and will not be stable. Try a higher
cutoff frequency or a different type/order of filter.
Error in filter_with_correction (line 51)
error('Calculated filter coefficients have poles on or outside the unit circle and will not be stable. Try a
higher cutoff frequency or a different type/order of filter.');
Error in ft_preproc_bandstopfilter (line 283)
filt = filter_with_correction(B,A,dat,dir,usefftfilt);
Error in spm_fnirs_preproc (line 113)
for j = 1:nf, Y = ft_preproc_bandstopfilter(Y', P.fs, P.K.C.cutoff(j,:), forder, ftype, fdir)'; end
Error in spm_fnirs_temporalpreproc_ui (line 155)
[fy, P] = spm_fnirs_preproc(y, P);
Error in spm_fnirs>push_temporal_Callback (line 69)
spm_fnirs_temporalpreproc_ui;
Error in gui_mainfcn (line 95)
feval(varargin{:});
Error in spm_fnirs (line 25)
gui_mainfcn(gui_State, varargin{:});
Error in @(hObject,eventdata)spm_fnirs('push_temporal_Callback',hObject,eventdata,guidata(hObject))
Error while evaluating UIControl Callback
==========================

This error was reported after when I observed the motion artifacts correction progress bar disappear. This error could get around by deselecting the cut-off filtering.

Thank you very much!

Best,
Victor