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gr002_errors.C
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1/// \file
2/// \ingroup tutorial_graphs
3/// \notebook -js
4/// \preview Create and draw a graph with error bars. If more graphs are needed, see the
5/// [gr03_err2gr.C](https://root.cern/doc/master/gerrors2_8C.html) tutorial
6///
7/// See the [TGraphErrors documentation](https://root.cern/doc/master/classTGraphErrors.html)
8///
9/// \macro_image
10/// \macro_code
11/// \author Rene Brun
12
13void gr002_errors() {
14 TCanvas *c1 = new TCanvas("c1","A Simple Graph with error bars",200,10,700,500);
15
16 c1->SetGrid();
17 c1->GetFrame()->SetBorderSize(12);
18
19 // We will use the constructor requiring: the number of points, arrays containing the x-and y-axis values, and arrays with the x- andy-axis errors
20 const Int_t n = 10;
21 Float_t x[n] = {-0.22, 0.05, 0.25, 0.35, 0.5, 0.61,0.7,0.85,0.89,0.95};
22 Float_t y[n] = {1,2.9,5.6,7.4,9,9.6,8.7,6.3,4.5,1};
23 Float_t ex[n] = {.05,.1,.07,.07,.04,.05,.06,.07,.08,.05};
24 Float_t ey[n] = {.8,.7,.6,.5,.4,.4,.5,.6,.7,.8};
25
26 // If all x-axis errors should zero, just provide a single 0 in place of ex
28
29 gr->SetTitle("TGraphErrors Example");
31 gr->SetMarkerStyle(21);
32
33 // To draw in a new/empty canvas or pad, include the option "A" so that the axes are drawn (leave it out if the graph is to be drawn on top of an existing plot
34 gr->Draw("ALP");
35
36 c1->Update();
37}
int Int_t
Definition RtypesCore.h:45
float Float_t
Definition RtypesCore.h:57
ROOT::Detail::TRangeCast< T, true > TRangeDynCast
TRangeDynCast is an adapter class that allows the typed iteration through a TCollection.
virtual void SetMarkerColor(Color_t mcolor=1)
Set the marker color.
Definition TAttMarker.h:39
virtual void SetMarkerStyle(Style_t mstyle=1)
Set the marker style.
Definition TAttMarker.h:41
The Canvas class.
Definition TCanvas.h:23
A TGraphErrors is a TGraph with error bars.
void Draw(Option_t *chopt="") override
Draw this graph with its current attributes.
Definition TGraph.cxx:833
void SetTitle(const char *title="") override
Change (i.e.
Definition TGraph.cxx:2402
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
const Int_t n
Definition legend1.C:16
TGraphErrors * gr
Definition legend1.C:25
Double_t ex[n]
Definition legend1.C:17