Filling histograms from a loop

ROOT
1

HI ,
I have noticed that if I try to fill more than ~20 histograms from a for loop then it becomes very slow. For example:

for(int i=0;i<nentries;i++){
nu_reco->GetEntry(i);
hist1->Fill(var1);
hist2->Fill(var2);

…
}

Could this be b/c I am using an older root verion - 4.04.2b

                                              -thanks Debdatta.
2

Hi,

Are you running this code in the interpreter or in compiled code? Currently the interpreter has some subtle limit on the code size it can optimized (aka once a loop or function becomes too big, it is no longer optimized).

Cheers,
Philippe.