GSI Forum
GSI Helmholtzzentrum für Schwerionenforschung

Home » PANDA » PandaRoot » Analysis » Covariance Matrices in RhoCandidates
Covariance Matrices in RhoCandidates [message #16042] Tue, 25 March 2014 14:51 Go to previous message
SHenssler is currently offline  SHenssler
Messages: 13
Registered: March 2014
Location: FZ Jülich
occasional visitor
From: *ext.kfa-juelich.de
Hello together,

I am currently evaulating alternative procedures for kinematic fitting and while doing some debugging i noticed, that the Covariance-Matrices i get are not positive-semi-definite.
I used the Rho-Macro for the kinematic fits and simply called my own routine after the vertex-fit was done (instead of calling the PndKinFitter).
My program also implements RhoFitterBase and after calling:

fDaughters.clear();
FindAndAddFinalStateDaughters(fHeadOfTree);

i take the P4-vectors and their covariances for each final state particle.
When i calcualte the eigenvectors for the covariances there are always some who are negative, which means the covariance matrices are not positive-semi-definite (i calculated the eigenvectors by hand for one example to make sure it is not a numeric problem and i get the same results).

Does anybody know something about this?

Thanks in andvance

Simon Henssler
 
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Previous Topic: option of polarization for Lambda-Lambdabar model
Next Topic: pi0 in fast simulation
Goto Forum:
  


Current Time: Wed Feb 20 06:05:44 CET 2019

Total time taken to generate the page: 0.02979 seconds