Hi Irene,
Yes, this is the way it is supposed to work.
If you want to set a minimum, you can add a statement
like the one shown below in your code.
Rene Brun
On Tue, 1 Oct 2002, Irene FIORI wrote:
>
> >>>>>>>>> now I included the test program (sorry!)
>
> Dear rooters,
> I have encountered the following "unexpected" beaviour
> of a TH1F histogram:
> I create a TH1F object and fill it with a set of (x,y) data points,
> the y coordinate being used "as a weight".
> I find that, as long as the minimum among the y values is negative,
> the vertical axis range is automatically set centered on the y values
>
> Instead, if the minimum among the y values is positive
> (no matter how big it is),
> the vertical axis first value is always set to 0. !!
>
> Below I pasted my test program,
> just try to switch OffSet between +10. and -10.
>
> Is this the way it is supposed to work?
> ...or am I missing something ??
> How I can have the vertical range centered on y values also in the
> second case??
>
> Thank you,
> Irene
>
> >>>>>>>>>>>>>>>>> test program
>
> void test_range()
> {
> TCanvas *c1 = new TCanvas("c1","This is a TEST",600,400);
> TH1F *h1 = new TH1F("h1","my histogram",100,0.,100.);
> Int_t i;
> Float_t OffSet = +10.; // -10.
> for (i=0;i<100;i++) h1->Fill(float(i), OffSet + gRandom->Gaus(0,1));
h1.SetMinimum(0.95*h1->GetMinimum()); //<===========NEW
> h1->Draw();
> c1->Update();
> }
>
>
>
>
>
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