[ROOT] Problem with TH1F vertical scale (fwd)

From: Irene FIORI (irene.fiori@pi.infn.it)
Date: Tue Oct 01 2002 - 17:20:36 MEST


>>>>>>>>> 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->Draw();
   c1->Update();  
}



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