Hi Tahsina,
Your definition of "total" is not correct. Instead of:
total = new TF1("total","landau(0)+gaus(0)",-20,200);
it should be:
total = new TF1("total","gaus(0)+landau(3)",-20,200);
Look again as it is defined in multifit.C
Rene Brun
Tahsina Ferdousi wrote:
>
> Hi Rooters,
>
> I was trying to fit a histogram with a gaussian+landau. My intention was
> as follows. The histogram ranges from -20 to 200. I want to fit the range
> from -20 to 10 with a gaussian and from 10 to 200 with a landau. Then I
> add the two fitting functions (gaus+landau) to fit the overall
> distribution. Here comes my problem I want the overall fit (which from now
> on we call "total") to follow a gaussian shape between -20 and 10 and then
> a landau shape between 10 and 200. But instead what I get is a continuous
> fitting shape (with no dip at 10 and no bump at 15, where the MPV of the
> landau is). I was following the "How to fit in a sub-range of an
> histogram" from the ROOT tutorial.
>
> I would appreciate if someone could kindly point me where I am doing wrong
> (or should I try some other procedure as $ROOTSYS/tutorials/FittingDemo.C
> where I define my own function).
>
> I am attaching the code I used (which is
> really $ROOTSYS/tutorials/multifit.C)
>
> //*************************
> TFile *f = new TFile("ADC_final.root");
> adc_high_cent4 = (TH1F*)f->Get("adc_high_cent4");
>
> g2 = new TF1("g2","landau",10,200);
> g1 = new TF1("g1","gaus",-20,10);
> total = new TF1("total","landau(0)+gaus(0)",-20,200);
> total->SetLineColor(2);
> g1->SetLineColor(4);
> adc_high_cent4->Fit("g1","R0");
> g1->GetParameters(&par[0]);
> adc_high_cent4->Fit("g2","R0+");
> g2->GetParameters(&par[3]);
> total->SetParameters(par);
> adc_high_cent4->Fit("total","R0+");
> adc_high_cent4->Draw();
> g1->Draw("same");
> g2->Draw("same");
> total->Draw("same");
> //*************************
>
> Best Regards,
>
> -tahsina
>
> -----------------------------------------------------------------------------
> Tahsina Ferdousi
> ------------------------------------------------------------------------------
> Graduate Student |email: |Phone:
> Department of Physics |tahsina@phyun0.ucr.edu |(909)-787-7301
> University of California |tahsina@ucrhi2.ucr.edu |
> Riverside, CA 92521 |url: |
> USA |www.phenix.bnl.gov/~tahsina|
> ------------------------------------------------------------------------------
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