Hi Rooters,
A few remarks:
(1) TH1::GetMaximum() returns the maximum bincontent as long as
TH1::SetMaximum() has not been used to set an upper limit on the
drawing range. It would be handy to have the drawing range and
the actual min/max of the histogram content to be decoupled. The
present behaviour is especially annoying if one tries to set the
drawing range by hand more than once. The function
TH1::GetMaximumStored() seems to be intended to do just this, but
only returns -1111 in my version of root.
(2) TH1::SetMaximum() takes a Float_t as an argument, even for a TH1D.
Likewise, TH1::GetMaximum() returns a Float_t. That leads to
trouble for large values in a TH1D.
(3) related to (2). Actually having Double_t values in a TH1D (say
1e200), results in an undrawable histogram. The same holds for TF1.
(4) if TH1::SetMaximum() has been used to set a maximum, drawing a 2D
histogram with the surf option ignores that maximum. The "lego"
option works fine.
(5) after filling a histogram with TH1::Eval(TF1* f1), switching on
the weighted error calculation using TH1::Sumw2() does not work.
Also, setting TH1::Sumw2() before using TH1::Eval() has no effect.
This is inconsistent with the normal behaviour.
(6) it would be very handy if TH1::Eval(TF1* f1, Option_t *option)
would also facilitate subtraction, multiplication and division and
not just addition. An possible application is fitting a function
and then calculating the residuals, or dividing out phasespace.
(7) having the "I" option (for integration) in TH1::Eval(TF1* f1) to
store the integrated function would be nice.
(8) TH1::GetXaxis()->Set(Int_t nbins, Axis_t xmin, Axis_t xmax) allows
one to change the number of bins on the axis, without actually
changing the number of histogram bins. Filling non-exisitent bins
will soon lead to a seg-fault. This should either be implemented
properly, or somehow be prevented. Although I have to admit that
I wouldn't know a legitimate reason to change the number of bins,
changing the upper and lower limit has many usefull applications.
I'm using version 2.23/12.
That's it for now,
-- Gerco
Dr. C.J.G. Onderwater
Nuclear Physics Laboratory
312 Loomis Laboratory of Physics
University of Illinois at Urbana-Champaign
1110 West Green Street
Urbana, IL 61801-3080
Phone : (217) 244-7363
Fax : (217) 333-1215
E-mail: onderwat@uiuc.edu
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