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gr005_apply.C File Reference

Detailed Description

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A macro to demonstrate the functionality of TGraph::Apply() method.

TGraph::Apply applies a function f to all the data TGraph points, f may be a 1-D function TF1 or 2-d function TF2. The Y values of the graph are replaced by the new values computed using the function.

The Apply() method can be used as well for TGraphErrors and TGraphAsymmErrors.

void gr005_apply() {
const Int_t npoints=3;
Double_t xaxis[npoints] = {1.,2.,3.};
Double_t yaxis[npoints] = {10.,20.,30.};
TF2 *ff = new TF2("ff","-1./y"); //Defining the function `f`
TCanvas *c1 = new TCanvas("c1","c1", 0,0,700,500);
c1->Divide(2,1);
c1->cd(1);
gr1->DrawClone("A*"); //Using DrawClone to create a copy of the graph in the canvas.
c1->cd(2);
gr1->Apply(ff); //Applies the function `f` to all the data TGraph points
gr1->Draw("A*");
/* Without DrawClone, the modifications to gr1 via Apply(ff) are reflected in the original graph
displayed in c1 (the two drawn graphs are not independent). */
}
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.
The Canvas class.
Definition TCanvas.h:23
A 2-Dim function with parameters.
Definition TF2.h:29
A TGraph is an object made of two arrays X and Y with npoints each.
Definition TGraph.h:41
return c1
Definition legend1.C:41
Author
Miro Helbich

Definition in file gr005_apply.C.