FFT problem

Roofit and RooStats
1

Dear all,
I have a problem using the FFT, if I do:

TH1 *hm =0;
TVirtualFFT::SetTransform(0);
hm = hresult->FFT(hm, “MAG”);

I get the hm (hresult is defined previously)

but it is not clear to me is I have hm and I need to do the inverse FFT which flag to put

thanks

2

Hi,

If you want to do the inverse you need both the real and the imaginary part since you are doing by default a real to complex transformation. You can do this using the option “C2R” with the TVirtualFFT class.
See root.cern.ch/root/htmldoc/TVirtualFFT.html

Lorenzo