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gr110_logscale.C File Reference

Detailed Description

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This tutorial demonstrates how to set a logarithmic scale for the axes of a graph using the SetLogScale() method.

The logarithmic scale can be applied to either the x-axis, the y-axis, or both axes at the same time. When using a logarithmic scale, the data must be positive since the logarithm is undefined for non-positive values and zero.

auto c = new TCanvas("c","Reversed graphs",0,0,900,400);
c->Divide(2,1);
c->cd(1);
const Int_t n = 6; //Fill the arrays x and y with the data points
Double_t x[n], y[n];
for (Int_t i=0;i<n;i++) {
x[i] = i+1;
y[i] = exp(i+1);
}
TGraph *gr1 = new TGraph(n,x,y);
gr1->SetLineColor(2);
gr1->SetLineWidth(4);
gr1->SetMarkerColor(4);
gr1->SetMarkerStyle(21);
gr1->SetTitle("Graph without log scale");
gr1->DrawClone("ACP");
//The logarithmic scale setting can also be done in a ROOT interactive session.
c->cd(2);
gPad->SetLogy();
//gPad->SetLogx(); Uncomment this line if log scale is needed on both axes
gr1->SetTitle("Graph with y log scale");
gr1->Draw("ACP");
}
#define c(i)
Definition RSha256.hxx:101
int Int_t
Definition RtypesCore.h:45
double Double_t
Definition RtypesCore.h:59
ROOT::Detail::TRangeCast< T, true > TRangeDynCast
TRangeDynCast is an adapter class that allows the typed iteration through a TCollection.
#define gPad
The Canvas class.
Definition TCanvas.h:23
A TGraph is an object made of two arrays X and Y with npoints each.
Definition TGraph.h:41
Double_t y[n]
Definition legend1.C:17
Double_t x[n]
Definition legend1.C:17
const Int_t n
Definition legend1.C:16
Date
25/11/2024
Author
Emanuele Chiamulera

Definition in file gr110_logscale.C.