How to integrate TH2 correctly?

ROOT
1

Hi,

I want to integrate bins in a subrange of a TH2D histogram but I fail with the syntax of Integral()

For example, how would I integrate a a rectangular subrange in (x_min,y_min) & (x_max,y_max)?
Following the Integral() definitions

I thought that it would work with

But ROOT computes the integral value for my test histogram as 0 although the histogram is definitely not empty…

Maybe somebody could help me with the correct syntax?

Cheers & Thanks,
Thomas

2

using

Double_t Integral(Int_t binx1, Int_t binx2, Int_t biny1, Int_t biny2, Option_t* option = "") with

binx1 = myhist->GetXaxis()->FindBin(xmin); binx2 = myhist->GetXaxis()->FindBin(xmax); biny1 = myhist->GetYaxis()->FindBin(ymin); biny2 = myhist->GetYaxis()->FindBin(ymax);
The TH1::FindBin function returns a global bin number (see doc)

Rene

3

Hi Rene,

many thanks – I have not considered that I have to ask the particular axis. But now it seems quite obvious :wink:

Thanks,
Thomas