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covariances in global coordinates [message #5985] Thu, 28 February 2008 12:23
Sebastian Neubert is currently offline  Sebastian Neubert
Messages: 282
Registered: March 2006
Location: Munich
first-grade participant

From: *e18.physik.tu-muenchen.de
Hi!

LSLTrackRep now can produce the required 6x6 covariances.

The respective methods are:

virtual TVectorT<double> getGlobal(); // (x,y,z,px,py,pz)
virtual TMatrixT<double> getGlobalCov(); // covariances


When the Kalman Filter has been run, this should produce a valid covariance. See also GenfitTester::test_LSLtoGLOB();

However there is one issue:
Since there is always one free parameter in a track (z in the case of LSLTrackRep) the 6x6 covariance matrix is a bit strange. For example at the moment the z-row/column has only the variance and no COvariances! I do not know how to solve this.
Originally this was the reason why I suggested that we should NOT have a 6-coordinate system.
But maybe there is a solution to this which I do not see at the moment.

At least you can start palying around now. Please give me some feedback on what you get! So far I have not investigated the covs too much!

Cheers! Sebastian.


Sebastian Neubert
Technische Universität München
Department Physik E18
sneubert@e18.physik.tu-muenchen.de
tel: +49-8928912592
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