I didn't write the Fourier stuff (that was Tom Ross, now of NIDA), but looking at the code, I don't see any builtin time series length limits. However, you could be running out of memory - the program has to store both the input dataset and the output dataset in RAM. When 3dFourier fails, do you get an error message?
If memory
is the problem, you could split the dataset into 2 (or more pieces)
in space using 3dZcutup, then filter each piece separately, then glue the results back together with 3dZcat, then delete the intermediate datasets. This would be a pain, I acknowledge, but could be automated in a script fairly easily.
bob cox
