BaseSoftConstraint Class Reference

Abstract base class for soft constraints of kinematic fits. More...

#include <BaseSoftConstraint.h>

Inheritance diagram for BaseSoftConstraint:

Collaboration diagram for BaseSoftConstraint:

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.
virtual void	addToGlobalChi2DerVector (double *y, int idim) const =0
	Add derivatives of chi squared to global derivative matrix.
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.
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!
virtual std::ostream &	print (std::ostream &os) const
	print object to ostream

Protected Attributes
char *	name

Related Functions
(Note that these are not member functions.)
std::ostream &	operator<< (std::ostream &os, const BaseConstraint &bc)
	Prints out a BaseConstraint, using its print method.

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

Definition at line 71 of file BaseSoftConstraint.h.

Member Function Documentation

add2ndDerivativesToMatrix()

virtual void add2ndDerivativesToMatrix ( double *  M, int  idim  ) const

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.

addToGlobalChi2DerVector()

virtual void addToGlobalChi2DerVector ( double *  y, int  idim  ) const

pure virtual

Add derivatives of chi squared to global derivative matrix.

Parameters

y	Vector of chi2 derivatives
idim	Vector size

Implemented in SoftGaussParticleConstraint.

getChi2()

virtual double getChi2 ( ) const

pure virtual

Returns the chi2.

Implemented in SoftGaussParticleConstraint.

getDerivatives()

virtual void getDerivatives ( int  idim, double  der[]  ) const

pure virtualinherited

Get first order derivatives of the constraint function Call this with a predefined array "der" with the necessary number of entries!

Parameters

idim	First dimension of array der
der	Array of derivatives, dimension at least idim x idim

Implemented in TrackConstraint, MassConstraint, MomentumConstraint, RecoilMassConstraint, SoftGaussMassConstraint, SoftGaussMomentumConstraint, BaseHardConstraint, and SoftGaussParticleConstraint.

getError()

double getError ( ) const

virtualinherited

Returns the error on the value of the constraint.

Reimplemented in BaseHardConstraint, and SoftGaussParticleConstraint.

Definition at line 70 of file BaseConstraint.cc.

    {
      assert(false);
      return 0;
    }

getName()

const char * getName ( ) const

virtualinherited

Returns the name of the constraint.

Definition at line 56 of file BaseConstraint.cc.

    {
      return name;
    }

getValue()

virtual double getValue ( ) const

pure virtualinherited

Returns the value of the constraint function.

Implemented in TrackConstraint, MassConstraint, MomentumConstraint, RecoilMassConstraint, SoftGaussMassConstraint, SoftGaussMomentumConstraint, BaseHardConstraint, and SoftGaussParticleConstraint.

print()

std::ostream & print ( std::ostream &  os ) const

virtualinherited

print object to ostream

Parameters

os	The output stream

Definition at line 76 of file BaseConstraint.cc.

    {
      os << getName() << "=" << getValue();
      return os;
    }

setName()

void setName ( const char *  name_ )

inherited

Set object's name.

Definition at line 61 of file BaseConstraint.cc.

    {
      if (name_ == nullptr) return;
      size_t l = strlen(name_);
      if (name) delete[] name;
      name = new char[l + 1];
      strcpy(name, name_);
    }

Friends And Related Function Documentation

operator<<()

std::ostream & operator<< ( std::ostream &  os, const BaseConstraint &  bc  )

related

Prints out a BaseConstraint, using its print method.

Parameters

os	The output stream
bc	The object to print

Definition at line 114 of file BaseConstraint.h.

    {
      return bc.print(os);
    }

Member Data Documentation

name

char* name

protectedinherited

Definition at line 108 of file BaseConstraint.h.

---

The documentation for this class was generated from the following files:

• analysis/OrcaKinFit/include/BaseSoftConstraint.h
• analysis/OrcaKinFit/src/BaseSoftConstraint.cc