example3.cpp File Reference

Example application. More...

#include <time.h>
#include "GblUtilities.h"
#include "GblTrajectory.h"

Go to the source code of this file.

Functions
void	example3 ()

Detailed Description

Example application.

Author

Claus Kleinwort, DESY, 2011 (Claus.nosp@m..Kle.nosp@m.inwor.nosp@m.t@de.nosp@m.sy.de)

Copyright

Copyright (c) 2011 - 2023 Deutsches Elektronen-Synchroton, Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details.

You should have received a copy of the GNU Library General Public License along with this program (see the file COPYING.LIB for more details); if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

Definition in file example3.cpp.

Function Documentation

example3()

void example3

(

)

Simple technical example (measure scattering).

Create points on initial trajectory, create trajectory from points, fit trajectory, get track parameter corrections and covariance matrix at points.

Equidistant measurement layers and thin scatterers, propagation with simple jacobian (quadratic in arc length differences). Curvilinear system (U,V,T) as local coordinate system.

This example simulates and refits tracks in a system of planar detectors with 2D measurements in a constant magnet field in Z direction using the curvilinear system as local system and (Q/P, slopes, offsets) as local track parameters. The true track parameters are randomly smeared with respect to a (constant and straight) reference trajectory with direction (lambda, phi) and are used (only) for the on-the-fly simulation of the measurements and scatterers. The predictions from the reference trajectory are therefore always zero and the residuals needed (by addMeasurement) are equal to the measurements.

This variant "measures" the scattering (variance) in layer 4 by adding two local parameters to describe the multiple scattering angle (without Chi2 bias).

Definition at line 37 of file example3.cpp.

References gbl::GblPoint::addLocals(), gbl::GblPoint::addMeasurement(), gbl::GblPoint::addScatterer(), gbl::GblTrajectory::fit(), gbl::gblSimpleJacobian(), gbl::GblTrajectory::getResults(), gbl::GblTrajectory::isValid(), and gbl::unrm().