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Reference Guide
fitExclude.C File Reference

Detailed Description

View in nbviewer Open in SWAN Illustrates how to fit excluding points in a given range.

FCN=84.1529 FROM MIGRAD STATUS=CONVERGED 31 CALLS 32 TOTAL
EDM=4.69843e-21 STRATEGY= 1 ERROR MATRIX ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 p0 2.84731e+01 9.46564e-01 1.81058e-03 -2.35464e-10
2 p1 -4.81581e+00 2.65330e-01 5.07521e-04 -8.40016e-10
#include <TH1.h>
#include <TF1.h>
#include <TROOT.h>
bool reject;
double fline(double *x, double *par)
{
if (reject && x[0] > 2.5 && x[0] < 3.5) {
return 0;
}
return par[0] + par[1]*x[0];
}
void fitExclude() {
//Create a source function
TF1 *f1 = new TF1("f1","[0] +[1]*x +gaus(2)",0,5);
f1->SetParameters(6,-1,5,3,0.2);
// create and fill histogram according to the source function
TH1F *h = new TH1F("h","background + signal",100,0,5);
h->FillRandom("f1",2000);
TF1 *fl = new TF1("fl",fline,0,5,2);
fl->SetParameters(2,-1);
//fit only the linear background excluding the signal area
reject = true;
h->Fit(fl,"0");
reject = false;
//store 2 separate functions for visualization
TF1 *fleft = new TF1("fleft",fline,0,2.5,2);
h->GetListOfFunctions()->Add(fleft);
gROOT->GetListOfFunctions()->Remove(fleft);
TF1 *fright = new TF1("fright",fline,3.5,5,2);
fright->SetParameters(fl->GetParameters());
h->GetListOfFunctions()->Add(fright);
gROOT->GetListOfFunctions()->Remove(fright);
h->Draw();
}
#define h(i)
Definition: RSha256.hxx:106
#define gROOT
Definition: TROOT.h:404
1-Dim function class
Definition: TF1.h:213
static void RejectPoint(Bool_t reject=kTRUE)
Static function to set the global flag to reject points the fgRejectPoint global flag is tested by al...
Definition: TF1.cxx:3692
virtual Double_t * GetParameters() const
Definition: TF1.h:525
virtual void SetParameters(const Double_t *params)
Definition: TF1.h:649
1-D histogram with a float per channel (see TH1 documentation)}
Definition: TH1.h:574
Double_t x[n]
Definition: legend1.C:17
TF1 * f1
Definition: legend1.C:11
Author
Rene Brun

Definition in file fitExclude.C.