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Reference Guide
graph2derrorsfit.C File Reference

Detailed Description

View in nbviewer Open in SWAN Draw and fit a TGraph2DErrors

#include <TMath.h>
#include <TGraph2DErrors.h>
#include <TRandom.h>
#include <TStyle.h>
#include <TCanvas.h>
#include <TF2.h>
void graph2derrorsfit()
{
TCanvas *c1 = new TCanvas("c1");
Double_t rnd, x, y, z, ex, ey, ez;
Double_t e = 0.3;
Int_t nd = 500;
TF2 *f2 = new TF2("f2","1000*(([0]*sin(x)/x)*([1]*sin(y)/y))+200",-6,6,-6,6);
f2->SetParameters(1,1);
// Fill the 2D graph
Double_t zmax = 0;
for (Int_t i=0; i<nd; i++) {
f2->GetRandom2(x,y);
rnd = r.Uniform(-e,e); // Generate a random number in [-e,e]
z = f2->Eval(x,y)*(1+rnd);
if (z>zmax) zmax = z;
dte->SetPoint(i,x,y,z);
ex = 0.05*r.Rndm();
ey = 0.05*r.Rndm();
ez = TMath::Abs(z*rnd);
dte->SetPointError(i,ex,ey,ez);
}
f2->SetParameters(0.5,1.5);
dte->Fit(f2);
TF2 *fit2 = (TF2*)dte->FindObject("f2");
fit2->SetTitle("Minuit fit result on the Graph2DErrors points");
fit2->SetMaximum(zmax);
fit2->SetLineColor(1);
fit2->SetLineWidth(1);
fit2->Draw("surf1");
dte->Draw("same p0");
}
#define e(i)
Definition: RSha256.hxx:103
int Int_t
Definition: RtypesCore.h:45
double Double_t
Definition: RtypesCore.h:59
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:414
virtual void SetLineWidth(Width_t lwidth)
Set the line width.
Definition: TAttLine.h:43
virtual void SetLineColor(Color_t lcolor)
Set the line color.
Definition: TAttLine.h:40
The Canvas class.
Definition: TCanvas.h:23
virtual void SetMaximum(Double_t maximum=-1111)
Set the maximum value along Y for this function In case the function is already drawn,...
Definition: TF1.cxx:3437
void SetTitle(const char *title="") override
Set function title if title has the form "fffffff;xxxx;yyyy", it is assumed that the function title i...
Definition: TF1.cxx:3595
virtual void SetParameters(const Double_t *params)
Definition: TF1.h:649
virtual Double_t Eval(Double_t x, Double_t y=0, Double_t z=0, Double_t t=0) const
Evaluate this function.
Definition: TF1.cxx:1454
A 2-Dim function with parameters.
Definition: TF2.h:29
virtual void GetRandom2(Double_t &xrandom, Double_t &yrandom, TRandom *rng=nullptr)
Return 2 random numbers following this function shape.
Definition: TF2.cxx:548
void Draw(Option_t *option="") override
Draw this function with its current attributes.
Definition: TF2.cxx:260
Graph 2D class with errors.
void SetPoint(Int_t i, Double_t x, Double_t y, Double_t z) override
Set x, y and z values for point number i.
virtual void SetPointError(Int_t i, Double_t ex, Double_t ey, Double_t ez)
Set ex, ey and ez values for point number i.
TObject * FindObject(const char *name) const override
search object named name in the list of functions
Definition: TGraph2D.cxx:769
virtual TFitResultPtr Fit(const char *formula, Option_t *option="", Option_t *goption="")
Fits this graph with function with name fname Predefined functions such as gaus, expo and poln are au...
Definition: TGraph2D.cxx:793
void Draw(Option_t *option="P0") override
Specific drawing options can be used to paint a TGraph2D:
Definition: TGraph2D.cxx:740
This is the base class for the ROOT Random number generators.
Definition: TRandom.h:27
void SetHistTopMargin(Double_t hmax=0.05)
Definition: TStyle.h:369
Double_t y[n]
Definition: legend1.C:17
return c1
Definition: legend1.C:41
Double_t x[n]
Definition: legend1.C:17
Double_t ey[n]
Definition: legend1.C:17
Double_t ex[n]
Definition: legend1.C:17
Short_t Abs(Short_t d)
Returns the absolute value of parameter Short_t d.
Definition: TMathBase.h:123
Author
Olivier Couet

Definition in file graph2derrorsfit.C.