PaintArrow shifted the bin center by an arbitrary value (0.03)

[couet]

The following example produced a weird plot:

{
   TH2D *blah = new TH2D("","",11,0.079,0.101,8,-0.0075,0.0005);
   for (int i=1; i<=blah->GetNbinsX();i++) {
      for (int j=1; j<=blah->GetNbinsY();j++) blah->SetBinContent(i, j, i*j);
   }
   blah->Draw("ARR");
}

This was because the bin center was shifted by an arbitrary value of 0.03. When the axis dynamic was large compared to 0.03 this was not visible. In the above example, it is not the case and therefore the plot was wrong. Removing that arbitrary shift gives the right plot.

This arbitrary shift comes from the 22 years old FORTRAN version of the code.

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[lmoneta]

LGTM !
Very strange ! Do you know what was the original reason for the 0.03 ?

[couet]

No, I do not know. That's the bin center clearly. Why was it shifted? I do not know.
But it fixes the problem and other examples work too.

[couet]

I went back to the Fortran and it was already like that. So there is no explanation.