I have a histogram, which represents some time series, for which I’d like to produce an FFT. I understand that ROOT has this capability, however I’m unable to find much documentation (a lot of what I’ve found appears to be dead links).
A couple questions. Firstly, do I understand correctly that FFT in ROOT is based on (or just a “wrapper” for?) FFTW? The time series in question does not have constant-time sampling (the samples are actually taken at random times, more or less). My understanding is that FFTW cannot be used on such time series. Is this the case for FFT in ROOT?
Second, how does one perform FFT on a histogram, in terms of the mechanics of it? I was able to find online some mentions of the different options available, however I don’t quite understand what each one does, so I started by simply trying a few combinations of different things and all I’m able to get is a straight line for the FFT.
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