Hi Ben,
I do not see anything wrong with the cut mechanism.
I tested a similar example with no problems.
My guess is that you forgot to divide the histogram by the bin width !!
You forgot to attach the files, so I cannot be more precise, but I am
pretty
convince that you forgot to take into account the bin width.
Rene Brun
On Wed, 3 Jan 2001, Benjamin E. Norman wrote:
> Hi Rooters,
> I have a problem with some code, and I was wondering if anyone has any
> suggestions. I'm trying to calculate dN/dpt^2 (1/pt dN/dpt) for some
> simulated data, and I get what seems to me like a strange
> inconsistency. The first time I tried it, I did the following:
>
> TCut isFinalState = "1<=ks && ks<=10";
> TCut isHminus = "kf==-211 || kf==-321 || kf==-2212";
> TCut isMidRapidity = "abs(eta) < 0.5";
> tree->Draw("pt>>histoDnDpt2",
> "1./pt" * (isFinalState && isHminus && isMidRapidity));
>
> This gives me the red curve on the enclosed graph. This didn't seem
> right, so I tried the following:
>
> tree->Draw("pt>>histoDnDpt2b",
> (isFinalState && isHminus && isMidRapidity));
> TF1* fIdentity = new TF1("fIdentity", "x");
> histoDnDpt2b->Divide(fIdentity);
>
> This gives me blue curve. I can understand that there will be some
> slight differences due to using the pt at the bin center in the second
> case, but this does not explain my problem. The difference in the
> curves at pt=0.2 GeV is a factor of 10, while the maximum difference in
> pt between the bin center and the bin edge is (0.2/0.005)=2.5%.
> So....am I missing something fundamental about histograms?
>
> Thanks,
> Ben
>
> ,,,,:,,,,:,,,,:,,,,:,,,,:,,,,:,,,,:,,,,:,,,,:,,,,:,,,,:,,,,
> Benjamin Norman http://kent.edu/~bnorman
> Department of Physics bnorman@kent.edu
> Kent State University, OH, USA 330-672-0378
> ````:````:````:````:````:````:````:````:````:````:````:````
>
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