Re: Can not use TGraph::Draw() and TGraphErrors::Draw()

Rene Brun (Rene.Brun@cern.ch)
Tue, 07 Oct 1997 10:59:59 +0200

Masayuki Eto wrote:
>
> Hi,
>
> I modified root/tutorials/gerrors.C as following:
>
> * Original
> Int_t n = 10;
> Float_t x[n] = {-0.22, 0.05, 0.25, 0.35, 0.5, 0.61,0.7,0.85,0.89,0.95};
> Float_t y[n] = {1,2.9,5.6,7.4,9,9.6,8.7,6.3,4.5,1};
> Float_t ex[n] = {.05,.1,.07,.07,.04,.05,.06,.07,.08,.05};
> Float_t ey[n] = {.8,.7,.6,.5,.4,.4,.5,.6,.7,.8};
>
> * Modified
> Int_t n = 5;
> Float_t x[n] = {-0.800000, -0.400000, 0.000000, 0.400000, 0.800000};
> Float_t y[n] = {204.263977, 201.577225, 199.746033, 198.477097, 197.912704};
> Float_t ex[n] = {0.200000, 0.200000, 0.200000, 0.200000, 0.200000};
> Float_t ey[n] = {0.467499, 0.350273, 0.337041, 0.345279, 0.449189};
>
> I did not change other lines in this file. But this program did not
> work because of "*** Break *** floating point exception".
>
> I also tried TGraph::Draw() with same data, but it did not work too.
>
> I tried root-1.03/04-cxx and root-1.03/04-g++ on DEC OSF1-Ver4.0.
>
> Why these did not work?
>
> Thanks.
> ---
> Masayuki Eto (etoh@mail.kek.jp)
> Dep.Phys., Tohoku Univ.

Thanks for reporting this problem.
The problem was easily traced to be a protection problem
in TH1::PaintHist. The bug appears only on alpha/unix.
I have fixed the problem and generated the tar files for alpha
machines (both cxx and g++) on our Web site.

Rene Brun