RE: [ROOT] Seg. Viol. after fitting

From: Philippe Canal (pcanal@fnal.gov)
Date: Tue Mar 05 2002 - 17:03:00 MET 

Hi Hermine,

I was unable to reproduce for problem with ROOT from the CVS repository
on linux.

However, I noted that you have:

  hLandauPart->DrawCopy();
  hLandauPart->Fit("myfunc","R");

You should note that this attaches the fitted function to the original
histogram and NOT to the copy created by DrawCopy.  An alternative would be:

  TH1F* copy = (TH1F*) hLandauPart->DrawClone();  // DrawClone is more general than DrawCopy.
  copy->Fit("myfunc","R");

To understand better your original problem, could send a stack trace of
the problem (i.e. gdb root.exe ... run ... .x tryFit.C)

Cheers,
Philippe.


-----Original Message-----
From: owner-roottalk@pcroot.cern.ch
[mailto:owner-roottalk@pcroot.cern.ch]On Behalf Of Hermine Woehri
Sent: Tuesday, March 05, 2002 8:09 AM
To: roottalk@cern.ch
Cc: rene.brun@cern.ch
Subject: [ROOT] Seg. Viol. after fitting


Hello,

I try to read a histogram from a ROOT-File, which I plot and further would
like to fit with a self-defined function. I attached this small macro,
since after successfully fitting (the fitting parameters are printed
onto the console) it crashes due to a Segmentation Violation.

However, I have observed, if I do the following steps, I do not have any
problems:

If I comment the last line, where the fit is performed:
//	hLandauPart->Fit("myfunc","R");
and run the
program, which simply plots the histogram and then RERUN the macro, this
time with the last line uncommented, then I succeed to also fit the
histogram.
So, what can I do in order to run the macro only once?

Thank you in advance,

Hermine

This archive was generated by hypermail 2b29 : Sat Jan 04 2003 - 23:50:44 MET