Can't plot all points of TGraphErrors

ROOT
1

Hello,

I have a TGraphErrors object which contains 6 points. However, when I draw it and set double logarithmic scale:

gr->Draw("ap");
gPad->SetLogx();
gPad->SetLogy();

Only 2 points instead of 6 are visible. Why I don’t see others?
The graph and the picture I get are attached.
My ROOT version is 5.17/03.

gr.png840×399 1.43 KB


graph.root (4.02 KB)

2

It seems your graph has points at x=0 and y=0 that is why they disapear in log scale. (log(0) is not valid).

3

That is not the case:

root [2] gr->Print() x[0]=200, y[0]=2.0271, ex[0]=0, ey[0]=1.04109 x[1]=400, y[1]=1.00335, ex[1]=0, ey[1]=0.505034 x[2]=1000, y[2]=0.500417, ex[2]=0, ey[2]=0.250626 x[3]=10000, y[3]=0.0600007, ex[3]=0, ey[3]=0.0300011 x[4]=30000, y[4]=0.0250001, ex[4]=0, ey[4]=0.0125001 x[5]=3e+06, y[5]=0.0005, ex[5]=0, ey[5]=0.00025

4

ok, I’ll have a closer look.

5

Of course, one can adjust the limits of both axes manually, but I’d like them to be in the proper values automatically.

6

If I execute the following macro it works. I get the attached plot:

void grapherrorslog()
{
   TFile f("grapherrors.root");
   gr->Draw("ap"); 
   gPad->SetLogx();
   gPad->SetLogy();
}

only when I run the same commands interactively I get the problem you described…
I am investigating.

c1.gif696×472 3.41 KB

7

adding gPad->Update(); after gr->Draw(“ap”); in the macro, produces also the problem.

8

Exactly! That was the cause of the problem in my case. I removed gPad->Update() and it helped. Of course, that would be great to get rid of this bug.

9

This is now fixed in the SVN trunk.