Here is a case in Guide:
TF1 efunc("efunc","exp([0]+[1]*x)",0.,5.);
efunc.SetParameter(0,1);
efunc.SetParameter(1,-1);
TH1F h("h","example histogram",100,0.,5.);
for (int i=0;i<1000;i++) {h.Fill(efunc.GetRandom());}
h.Draw();
and the result is:
Info in <TCanvas::MakeDefCanvas>: created default TCanvas with name c1
without any Histogram was shown.
ROOT Version: 6.24.02
Platform: Ubuntu
Compiler: Not Provided
Hi,
Can you modify your macro and create objects dynamically:
TF1 efunc("efunc","exp([0]+[1]*x)",0.,5.);
efunc.SetParameter(0,1);
efunc.SetParameter(1,-1);
auto h = new TH1F("h","example histogram",100,0.,5.);
for (int i=0;i<1000;i++) {h->Fill(efunc.GetRandom());}
h->Draw();
Otherwise object is destroyed before it can be painted.
Well, I don’t understand “object is destroyed”. The code is from here:A ROOT Guide For Beginners. Even I tried
auto h = new TH1F("h","example histogram",100,0.,5.);
The result is still
Info in <TCanvas::MakeDefCanvas>: created default TCanvas with name c1
without any graph
When you creates histogram with:
TH1F h("h","example histogram",100,0.,5.);
it automatically destroyed when leaving function scope.
Canvas rendering performed afterwards - therefore canvas does not “see” such object.
When object created dynamically with new operator, it will remain “alive” and can be rendered.
Does modified code works for you?
