Hi Robert,
In a macro, you must call TCanvas::Update(). See the explanations in:
http://root.cern.ch/root/HowtoDraw.html
Here is a small example:
{
TCanvas *c1 = new TCanvas("c1","c1",10,10,500,800);
TH1F h("h","test",100,-4,4);
h.FillRandom("gaus",10000);
c1->Divide(1,3);
c1->cd(3);
h->Draw();
c1->Update();
printf("PadLow=%g,
PadHigh=%g\n",gPad->GetFrame()->GetY1(),gPad->GetFrame()->GetY2());
printf("PadLow=%g, PadHigh=%g\n",gPad->GetUymin(),gPad->GetUymax());
}
Rene Brun
}Robert Zitoun wrote:
>
> I want know the y-limits of a histogram made automatically.
>
> I get the values I want when I type interactively
>
> c1->cd(3);
> h->Draw();
> gPad->GetFrame()->GetY1();
> gPad->GetFrame()->GetY2();
>
> However, when I do it within a macro, I get Y1=0 and Y2=1;
> I suspect this is due to "gPad" which does not work as I think.
> So how do I get the y-limits.
>
> Robert
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