I like very much the feature of ntuple->Draw("x-2y:z","z>0")
But as far as I can tell this clever code in TTree.cxx is underused.
OK, I can fill a histogram, I can fill a TPolyMarker, but I would like to be
able to fill a TGraph class and then use TGraph:Fit. I some cases points
would need to be sorted.
I just think that TNtuple(TTree) is the most convinient class for me to store
my spectra which consist of wavelength, and then several data channels
recorded. Various functions of them need to be plotted to get meaningful
information, but they are not to be treated as histograms. I have noticed the
same weakness in PAW: there was no easy way to get functions of ntuple
fields as vectors.
What I am in fact asking for is the simplest way to fit e.g. pol4
x*(1+2*z) = pol4 (3*y+x) for z>x where x,y,z are TNtuple fields.
Another problem is that ROOT's most developed objects are histograms, but my
data represents value AT some point, not mean value in some range. I can
probably construct histograms in such a way that bin centers correspond to my
data points, but is there any cleaner solution?
I would like to develop solutions for above mentioned problems, but please
tell me if this is not already done.
Best regards,
--
Tomasz Motylewski
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