# SetDefaultSumw2

Hi,

I’m using ROOT 5.18/00 and I’d like to use TH1::SetDefaultSumw2 to ensure that all histograms are created with the sum of weights. I try like this but it doesn’t seem to do anything:

TH1::SetDefaultSumw2()
TH1F *h = new TH1F(“h”,"",11,0,10);
h->Sumw2() //just to test if I’ve set the weights
I don’t get the warning about having set Sumw2 already. Also, when I test it out, I don’t have the errors for weighted histograms computed correctly.

Am I calling it wrong somehow?

Thanks a lot!
Heather

We do not print the Warning message in case TH1::SetDefaultSumw2 has been called.

Rene

Ok, I think I confused myself earlier. Now it is working fine - thanks!