<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">\section{Particle\-Constraint Class Reference}
\label{classParticleConstraint}\index{Particle\-Constraint@{Particle\-Constraint}}


Abstract base class for constraints of kinematic fits.  




{\ttfamily \#include $&lt;$Particle\-Constraint.\-h$&gt;$}

Inheritance diagram for Particle\-Constraint\-:\begin{figure}[H]
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\leavevmode
\includegraphics[height=4.000000cm]{classParticleConstraint}
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\subsection*{Public Member Functions}
\begin{DoxyCompactItemize}
\item 
{\bf Particle\-Constraint} ()\label{classParticleConstraint_a49398205c7a7cd8503691bcf8a3b3eda}

\begin{DoxyCompactList}\small\item\em Creates an empty \doxyref{Particle\-Constraint}{p.}{classParticleConstraint} object. \end{DoxyCompactList}\item 
virtual {\bf $\sim$\-Particle\-Constraint} ()\label{classParticleConstraint_ac97e6c3f8b73003626017dd020307ff7}

\begin{DoxyCompactList}\small\item\em Virtual destructor. \end{DoxyCompactList}\item 
virtual void {\bf set\-F\-O\-List} (std\-::vector$&lt;$ {\bf Particle\-Fit\-Object} $\ast$ $&gt;$ $\ast$fitobjects\-\_\-)
\begin{DoxyCompactList}\small\item\em Adds several \doxyref{Particle\-Fit\-Object}{p.}{classParticleFitObject} objects to the list. \end{DoxyCompactList}\item 
virtual void {\bf add\-To\-F\-O\-List} ({\bf Particle\-Fit\-Object} \&amp;fitobject, int flag=1)\label{classParticleConstraint_a7856341e22f81722f540e765b5224be4}

\begin{DoxyCompactList}\small\item\em Adds one \doxyref{Particle\-Fit\-Object}{p.}{classParticleFitObject} objects to the list. \end{DoxyCompactList}\item 
virtual void {\bf reset\-F\-O\-List} ()\label{classParticleConstraint_a81fef45e48701f14da17fd78d5da9d83}

\begin{DoxyCompactList}\small\item\em Resests \doxyref{Particle\-Fit\-Object}{p.}{classParticleFitObject} list. \end{DoxyCompactList}\item 
virtual void {\bf invalidate\-Cache} () const \label{classParticleConstraint_a4cd0812b322b120a21c7d270cf59b637}

\begin{DoxyCompactList}\small\item\em Invalidates any cached values for the next event. \end{DoxyCompactList}\end{DoxyCompactItemize}
\subsection*{Additional Inherited Members}


\subsection{Detailed Description}
Abstract base class for 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 Fit\-Object) 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 \doxyref{Particle\-Fit\-Object}{p.}{classParticleFitObject} and can be either set a whole (set\-F\-O\-List) or enlarged by adding a single \doxyref{Particle\-Fit\-Object}{p.}{classParticleFitObject} (add\-To\-F\-O\-List).

From the four--momenta of all concerned fit objects the constraint has to be able to calculate its current value (get\-Value). 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 Fit\-Object 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 Fit\-Object. Thus it is easily possible to use Fit\-Objects with different kinds of parametrisations under the same constraint. Some fit algorithms also need the second derivatives of the constraint, i.\-e. the Newton\-Fitter.

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 (add1st\-Derivatives\-To\-Matrix, add2nd\-Derivatives\-To\-Matrix). This requires the constraint to know its position in the overall list of constraints (global\-Num).

Author\-: Jenny List, Benno List \begin{DoxyParagraph}{Date\-:}
2008/02/12 16\-:43\-:26 
\end{DoxyParagraph}
\begin{DoxyParagraph}{Author\-:}
blist 
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\subsection{Member Function Documentation}
\index{Particle\-Constraint@{Particle\-Constraint}!set\-F\-O\-List@{set\-F\-O\-List}}
\index{set\-F\-O\-List@{set\-F\-O\-List}!ParticleConstraint@{Particle\-Constraint}}
\subsubsection[{set\-F\-O\-List}]{\setlength{\rightskip}{0pt plus 5cm}virtual void Particle\-Constraint\-::set\-F\-O\-List (
\begin{DoxyParamCaption}
\item[{std\-::vector$&lt;$ {\bf Particle\-Fit\-Object} $\ast$ $&gt;$ $\ast$}]{fitobjects\-\_\-}
\end{DoxyParamCaption}
)\hspace{0.3cm}{\ttfamily [inline]}, {\ttfamily [virtual]}}\label{classParticleConstraint_abe40bc66548455f1798507cdf3890027}


Adds several \doxyref{Particle\-Fit\-Object}{p.}{classParticleFitObject} objects to the list. 


\begin{DoxyParams}{Parameters}
{\em fitobjects\-\_\-} &amp; A list of \doxyref{Base\-Fit\-Object}{p.}{classBaseFitObject} objects \\
\hline
\end{DoxyParams}


References Base\-Hard\-Constraint\-::fitobjects, and Base\-Hard\-Constraint\-::flags.



The documentation for this class was generated from the following file\-:\begin{DoxyCompactItemize}
\item 
{\bf Particle\-Constraint.\-h}\end{DoxyCompactItemize}
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