Hello R Sak,
It looks like there was a misunderstanding regarding the use of the 'freqrange' argument in the 'pmtm' function. The 'freqrange' parameter you are referring to specifies the type of the Power Spectral Density (PSD) estimate returned ('onesided', 'twosided', or 'centered'), rather than allowing you to directly specify a numeric frequency range (e.g., 
Hz) for the analysis.
Hz) for the analysis.Given this clarification, here's how you can use the 'freqrange' argument correctly with the 'pmtm' function:
% Your pre-processed EEG signal is in 'smoothdata'
Fs = 256; % Sampling frequency
NW = 2.5; % Time-halfbandwidth product, adjust as needed
% Estimate PSD with 'onesided', 'twosided', or 'centered' spectrum
[Pxx, F] = pmtm(smoothdata, NW, [], Fs, 'onesided'); % Example for 'onesided'
% If you need to analyze a specific frequency range, e.g., 0-4 Hz, after estimation:
idx = F >= 0 & F <= 4;
Pxx_range = Pxx(idx);
F_range = F(idx);
% 'Pxx_range' and 'F_range' contain the PSD values and frequencies for 0-4 Hz, respectively
Note that the choice between 'onesided', 'twosided', and 'centered' depends on the nature of your input signal (real-valued or complex-valued) and your analysis requirements.
For more information about the syntax and different use cases, refer to the documentation:
I hope this helps!
