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graph2dfit.C File Reference

## Detailed Description

Fitting a TGraph2D

****************************************
Chi2 = 4.25425e+06
NDf = 398
Edm = 5.85197e-13
NCalls = 45
p0 = 0.574556 +/- 0.109977
p1 = 1.72367 +/- 0.329932
#include <TMath.h>
#include <TGraph2D.h>
#include <TRandom.h>
#include <TStyle.h>
#include <TCanvas.h>
#include <TF2.h>
#include <TH1.h>
void graph2dfit()
{
auto c = new TCanvas("c","Graph2D example",0,0,600,800);
c->Divide(2,3);
double rnd, x, y, z;
double e = 0.3;
int nd = 400;
int np = 10000;
double fl = 6;
auto f2 = new TF2("f2","1000*(([0]*sin(x)/x)*([1]*sin(y)/y))+200",
-fl,fl,-fl,fl);
f2->SetParameters(1,1);
auto dt = new TGraph2D();
// Fill the 2D graph
double zmax = 0;
for (int N=0; N<nd; N++) {
f2->GetRandom2(x,y);
// Generate a random number in [-e,e]
rnd = 2*r.Rndm()*e-e;
z = f2->Eval(x,y)*(1+rnd);
if (z>zmax) zmax = z;
dt->SetPoint(N,x,y,z);
}
double hr = 350;
auto h1 = new TH1D("h1",
"#splitline{Difference between Original}{#splitline{function and Function}{with noise}}",
100, -hr, hr);
auto h2 = new TH1D("h2",
"#splitline{Difference between Original}{#splitline{function and Delaunay triangles}{interpolation}}",
100, -hr, hr);
auto h3 = new TH1D("h3",
"#splitline{Difference between Original}{function and Minuit fit}",
500, -hr, hr);
f2->SetParameters(0.5,1.5);
dt->Fit(f2);
auto fit2 = (TF2*)dt->FindObject("f2");
f2->SetParameters(1,1);
for (int N=0; N<np; N++) {
f2->GetRandom2(x,y);
// Generate a random number in [-e,e]
rnd = 2*r.Rndm()*e-e;
z = f2->Eval(x,y)*(1+rnd);
h1->Fill(f2->Eval(x,y)-z);
z = dt->Interpolate(x,y);
h2->Fill(f2->Eval(x,y)-z);
z = fit2->Eval(x,y);
h3->Fill(f2->Eval(x,y)-z);
}
c->cd(1);
f2->SetTitle("Original function with Graph2D points on top");
f2->SetMaximum(zmax);
f2->Draw("surf1");
dt->Draw("same p0");
c->cd(3);
dt->SetMargin(0.1);
dt->SetFillColor(36);
dt->SetTitle("Histogram produced with Delaunay interpolation");
dt->Draw("surf4");
c->cd(5);
fit2->SetTitle("Minuit fit result on the Graph2D points");
fit2->Draw("surf1");
h2->SetFillColor(38);
h3->SetFillColor(29);
c->cd(2); h1->Fit("gaus","Q") ; h1->Draw();
c->cd(4); h2->Fit("gaus","Q") ; h2->Draw();
c->cd(6); h3->Fit("gaus","Q") ; h3->Draw();
c->cd();
}
#define c(i)
Definition RSha256.hxx:101
#define e(i)
Definition RSha256.hxx:103
#define N
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void char Point_t Rectangle_t WindowAttributes_t Float_t Float_t Float_t Int_t Int_t UInt_t UInt_t Rectangle_t Int_t Int_t Window_t TString Int_t GCValues_t GetPrimarySelectionOwner GetDisplay GetScreen GetColormap GetNativeEvent const char const char dpyName wid window const char font_name cursor keysym reg const char only_if_exist regb h Point_t np
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void char Point_t Rectangle_t WindowAttributes_t Float_t r
R__EXTERN TStyle * gStyle
Definition TStyle.h:433
virtual void SetFillColor(Color_t fcolor)
Set the fill area color.
Definition TAttFill.h:37
The Canvas class.
Definition TCanvas.h:23
A 2-Dim function with parameters.
Definition TF2.h:29
Graphics object made of three arrays X, Y and Z with the same number of points each.
Definition TGraph2D.h:41
1-D histogram with a double per channel (see TH1 documentation)}
Definition TH1.h:620
virtual TFitResultPtr Fit(const char *formula, Option_t *option="", Option_t *goption="", Double_t xmin=0, Double_t xmax=0)
Fit histogram with function fname.
Definition TH1.cxx:3897
virtual Int_t Fill(Double_t x)
Increment bin with abscissa X by 1.
Definition TH1.cxx:3341
void Draw(Option_t *option="") override
Draw this histogram with options.
Definition TH1.cxx:3063
This is the base class for the ROOT Random number generators.
Definition TRandom.h:27
void SetOptStat(Int_t stat=1)
The type of information printed in the histogram statistics box can be selected via the parameter mod...
Definition TStyle.cxx:1636
void SetHistTopMargin(Double_t hmax=0.05)
Definition TStyle.h:382
void SetOptFit(Int_t fit=1)
The type of information about fit parameters printed in the histogram statistics box can be selected ...
Definition TStyle.cxx:1589
Double_t y[n]
Definition legend1.C:17
Double_t x[n]
Definition legend1.C:17
TH1F * h1
Definition legend1.C:5

Definition in file graph2dfit.C.