Hi Andrzej,
Currently, when a branch holds a variable of type integer, the histogram
created has an integer bin size.
However, the algorithm is not clever enough to recognize that Time-10008884
is also an integer. As soon as an expression is used, the bin size is
assumed to be a float.
You should create an histogram with the correct bin limits and bin size
before calling TTree::Draw, then do:
tree->Draw("Time-10008884>>myhist");
Rene Brun
Andrzej Kupsc wrote:
>
> Hi,
> In a tree I have a branch with C-time (secs>1970):
>
> tree->Branch("Time",&Time,"Time/i");
>
> When I am plotting time vs other other variable say:
> tree->Draw("x:Time")
> The bins are much more coarse then in the case when time offset
> was subtraced:
> tree->Draw("x:(Time-1000883184)")
>
> There is not such big difference in automaticaly calculated bin
> size when one dimensional plot is requested:
> tree->Draw("Time") vs tree->Draw("Time-1000883184")
>
> I am using root 3.01/06 on RH7.0
>
> Am I doing something wrong?
>
> Best regards
> Andrzej Kupsc
> ---------------------------------------------------------------
> Address : The Svedberg Laboratory,
> Uppsala University, Box 533, S-75121 Uppsala.
> Telephone : +46-18-4713439
> Facsimile : +46-18-4713833
> e-mail : kupsc@unix.tsl.uu.se
> ---------------------------------------------------------------
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