Abstract base class for soft constraints of kinematic fits. More...
#include <BaseSoftConstraint.h>
Public Member Functions | |
| virtual | ~BaseSoftConstraint () |
| Virtual destructor. | |
| virtual double | getChi2 () const =0 |
| Returns the chi2. | |
| virtual void | add2ndDerivativesToMatrix (double *M, int idim) const =0 |
| Adds second order derivatives to global covariance matrix M. More... | |
| virtual void | addToGlobalChi2DerVector (double *y, int idim) const =0 |
| Add derivatives of chi squared to global derivative matrix. More... | |
 Public Member Functions inherited from BaseConstraint | |
| BaseConstraint () | |
| Creates an empty BaseConstraint object. | |
| BaseConstraint (const BaseConstraint &rhs) | |
| Copy constructor. More... | |
| BaseConstraint & | operator= (const BaseConstraint &rhs) |
| Assignment. More... | |
| virtual | ~BaseConstraint () |
| Virtual destructor. | |
| virtual double | getValue () const =0 |
| Returns the value of the constraint function. | |
| virtual double | getError () const |
| Returns the error on the value of the constraint. | |
| virtual const char * | getName () const |
| Returns the name of the constraint. | |
| virtual void | setName (const char *name_) |
| Set object's name. | |
| virtual void | getDerivatives (int idim, double der[]) const =0 |
| Get first order derivatives of the constraint function Call this with a predefined array "der" with the necessary number of entries! More... | |
| virtual std::ostream & | print (std::ostream &os) const |
| print object to ostream More... | |
Protected Attributes | |
| char * | name |
| Protected Attributes inherited from BaseConstraint | |
| char * | name |
Additional Inherited Members | |
| Related Functions inherited from BaseConstraint | |
| std::ostream & | operator<< (std::ostream &os, const BaseConstraint &bc) |
| Prints out a BaseConstraint, using its print method. More... | |
Detailed Description
Abstract base class for soft constraints of kinematic fits.
This class defines the minimal functionality any constraint class must provide. First of all a constraint should know on with particles (or FitObject) it is applied. Where as for example a constraint on the total transvese momentum takes into account all particles in the event, an invariant mass constraint usually applies only to a subset of particles.
The particle list is implemented as a vector containing pointers to objects derived from BaseFitObject and can be either set a whole (setFOList) or enlarged by adding a single BaseFitObject (addToFOList).
From the four–momenta of all concerned fit objects the constraint has to be able to calculate its current value (getValue). Constraints should be formulated such that a value of zero corresponds to a perfectly fulfilled constraint.
In order to find a solution to the constrained minimisation problem, fit algorithms usually need the first order derivatives of the constraint with respect to the fit parameters. Since many constraints can be most easily expressed in terms of E, px, py, pz, the constraints supply their derivatives w.r.t. these parameters. If a FitObject uses a different parametrisation, it is its own task to provide the additional derivatives of E, px, py, pz w.r.t. the parameters of the FitObject. Thus it is easily possible to use FitObjects with different kinds of parametrisations under the same constraint. Some fit algorithms also need the second derivatives of the constraint, i.e. the NewtonFitter.
First and second order derivatives of each constraint can be added directly to the global covariance matrix containing the derivatives of all constraints w.r.t. to all parameters (add1stDerivativesToMatrix, add2ndDerivativesToMatrix). This requires the constraint to know its position in the overall list of constraints (globalNum).
Author: Jenny List, Benno List Last update:
- Date:
- 2011/03/03 15:03:02
by:
- Author:
- blist
Member Function Documentation
|
pure virtual |
Adds second order derivatives to global covariance matrix M.
- Parameters
-
M Global covariance matrix, dimension at least idim x idim idim First dimension of array der
Implemented in SoftGaussParticleConstraint.
|
pure virtual |
Add derivatives of chi squared to global derivative matrix.
- Parameters
-
y Vector of chi2 derivatives idim Vector size
Implemented in SoftGaussParticleConstraint.
The documentation for this class was generated from the following files:
