Subtracting histograms does not yield difference in entries

[Wile_E_Coyote]

Subtracting multiple histogram with same TH2F

I guess you could be interested in the TH1:Integral / TH2::Integral / TH3::Integral and / or the TH1::IntegralAndError / TH2::IntegralAndError / TH3::IntegralAndError methods. When you “subtract” histograms, the “number of entries” is recalculated in a different way than when you “add” them so, you may get “unexpected” / “weird” values. { TH1F *h1 = new TH1F("h1", "h1", 100, -5., 5.); h1->Sumw2(kTRUE); #if 0 /* 0 or 1 */ h1->FillRandom("gaus"); #else /* 0 or 1 */ for (Int_t i = 0; i < …