Bug #1988

CTA event simulation for energy range with zero effective area throws an exception

Added by Knödlseder Jürgen almost 7 years ago. Updated almost 7 years ago.

Status:ClosedStart date:04/05/2017
Priority:HighDue date:
Assigned To:Eschbach Stefan% Done:

100%

Category:-
Target version:1.3.0
Duration:

Description

If CTA events are simulated for an energy range where the effective area is zero the GModelSpectralNodes::append() method throws an exception.

The reason is that the code in GCTAModelAeffBackground::mc

        GModelSpectralNodes spectral;
        for (int i = 0; i < spectral_ebounds.size(); ++i) {
            GEnergy energy   = spectral_ebounds.elogmean(i);
            double intensity = aeff_integral(obs, energy.log10TeV());
            double  norm     = m_spectral->eval(energy, events->tstart());
            spectral.append(energy, norm * intensity);
        }
does not check whether the product norm * intensity is positive, which leads to the exception. A test should be added that appends only positive nodes.

The side effect is that the GModelSpectralNodes object may be empty, which later poses a problem in GModelSpectralNodes::flux that returns an exception if there are no nodes. Instead, the method should simply return zero.


Recurrence

No recurrence.

History

#1 Updated by Eschbach Stefan almost 7 years ago

  • Status changed from New to Pull request
  • % Done changed from 0 to 50

I implemented a statement to check if “norm*intensity>0” and only appends if this is true.
The missing aeff-entry leads to getting stuck in a do-loop later in the code, because the variable “value” will be zero then.
I fixed this by adding another statement that breaks the loop if there were 100 trys and value still stays zero.

I’m not a 100% sure if this leads to further problems in specific cases, in my case it seems to work now.

Changes are implemented in seschbach/gammalib 1988-Change-Effective-Area

#2 Updated by Knödlseder Jürgen almost 7 years ago

  • Status changed from Pull request to Closed
  • Assigned To set to Eschbach Stefan
  • % Done changed from 50 to 100

Code merged into devel.

Also available in: Atom PDF