Hi everybody,
I am fitting with different functions an histogram:
h_en_cm_photon.Draw("e1")
c1.SetLogy()
h_en_cm_photon.Fit("expo","R","EI",60,120)
TF1 *Au_fit_direct = new TF1(*(h_en_cm_photon.GetFunction("expo")))
Au_fit_direct.SetName("Au_fit_direct")
Au_fit_direct.SetRange(0,200);
Au_fit_direct.Draw("e1same")
TH1F *Au_direct = new TH1F(*(Au_fit_direct.GetHistogram()))
TH1F *Au_direct_subs = new
TH1F("Au_direct_subs","Au_direct_subs",h_en_cm_photon.GetNbinsX(),0,200)
Au_direct_subs.Sumw2();
Au_direct_subs.Add(h_en_cm_photon,Au_direct,1,-1);
Au_direct_subs.Draw("e1")
Au_direct_subs.Fit("expo","R","EI",30,50)
TF1 *Au_fit_therm = new TF1(*(Au_direct_subs.GetFunction("expo")))
Au_fit_therm.SetRange(0,200);
Au_fit_therm.SetName("Au_fit_therm")
Au_fit_therm.Draw("e1same")
TH1F *Au_therm = new TH1F(*(Au_fit_therm.GetHistogram()))
Au_therm.Draw("e1same")
h_en_cm_photon.Draw("e1")
Au_direct.Draw("e1same")
Au_therm.Draw("e1same")
h_en_cm_photon.Fit("Au_fit_direct + Au_fit_therm","R","",10,25)
Everything works as expected but the last instruction gives:
"Unknown function: Au_fit_direct + Au_fit_therm"
When, alternatively, trying to define a new function from the existent
ones via :
TF1 *Au_fit_total = new TF1("Au_fit_direct + Au_fit_therm")
I get "Error: illegal pointer to class object Au_fit_total" when trying
to draw it (Au_fit_total.Draw())....
Briefly, I don't get to know how to operate with functions created via
histo.GetFunction() to create new functions or to use them to fit
histograms .... and the Class Description for TFormula and TF1 (as well
as the different examples in the web) don't give me an answer (as far as
I know) ....
So, where I'm wrong ?
Thanks in advance,
David d'Enterria
----------------
TAPS (Subatech) phone : 02.51.85.84.89
mailto:enterria@in2p3.fr http://taps.in2p3.fr/nof/
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