*ROOT Version:* 6.10.04-x86_64-slc6-gcc62-opt

*Platform:* lxplus

*Compiler:* Not Provided

Hi!

I have a TH2F histogram, that I am scaling per “line” in y along the x axis. I already know this sounds confusing, so I will just add here the function that does that for me:

```
void ScaleLineX(TH2F* hist,int bin_x_max, int bin_y_max){
double integral_line=0;
for(int x=0; x<=bin_x_max; x++){
integral_line = hist->Integral(x, x, 0, bin_y_max);
if(integral_line>0){
for(int y=1; y<=bin_y_max; y++){
hist->SetBinContent(x, y, hist->GetBinContent(x,y)/integral_line);
}
}
}
}
```

that I call with

`ScaleLineX(hist, hist->GetNbinsX()+1, hist->GetNbinsY()+1);`

if I have scaled the histogram like this, the errors on a ProfileX (called without options) on that histogram seem to be now the RMS instead of the RMS/sqrt(n).

I am not sure I understand the behaviour, would be happy if somebody has an explanation!

Thanks a lot,

Alex

PS: I have put for testing the rootfile I use on lxplus (/afs/cern.ch/user/a/aleopold/public/rootforum/output.root, the th2f called “hist_nhits_over_eta”)