AliPhysics  a3be53f (a3be53f)
LinearVarianceCombiner Struct Reference
Inheritance diagram for LinearVarianceCombiner:

## Public Member Functions

double W (const Result &r) const

double StepW (double guess, const Result &r) const

double StepOffset (double guess, const Result &r) const

double TermVar (double guess, const Result &r) const

Public Member Functions inherited from Combiner
virtual ~Combiner ()

double Term (double guess, const Result &r) const

double F (double guess, double chi2, const_iterator &begin, const_iterator &end) const

double FindError (unsigned short nIter, const_iterator &begin, const_iterator &end, int sign, double best, double chi2, double s)

double FindX (unsigned short nIter, const_iterator &begin, const_iterator &end, double lowest, double highest)

Final Calculate (const_iterator &begin, const_iterator &end, unsigned short nIter=50)

## Static Public Member Functions

static double L (double guess, double x, double el, double eh)

static double WrapL (double *xp, double *pp)

Public Types inherited from Combiner
typedef List::iterator iterator

typedef List::const_iterator const_iterator

## Detailed Description

A combiner that uses a linear variance approximation

Definition at line 572 of file Combiner.C.

## Member Function Documentation

 static double LinearVarianceCombiner::L ( double guess, double x, double el, double eh )
inlinestatic

Return the likely-hood function value at $$x'$$:

$L(x') = (x'-x)^2 / (V + V'(x'-x))$

where

$v = \sigma^\sigma^-$

$v' = \sigma^+-\sigma^-$

Parameters
 guess $$x'$$ x $$x$$ el $$\sigma^-$$ eh $$\sigma^+$$
Returns

Definition at line 664 of file Combiner.C.

 double LinearVarianceCombiner::StepOffset ( double guess, const Result & r ) const
inlinevirtual

Calculate the bias.

$\delta(x') = 1/2 V' [(x'-x) / (V + V'(x' - x))]^2$

Parameters
 guess Current guess $$x'$$ r Observation
Returns
$$\delta(x')$$

Implements Combiner.

Definition at line 620 of file Combiner.C.

 double LinearVarianceCombiner::StepW ( double guess, const Result & r ) const
inlinevirtual

Calculate the weight based on a guess of best $$x'$$

$W(x') = v / [V + V' (x' - x)]^2$

Parameters
 guess Current guess $$x'$$ r Observation
Returns
$$W(x')$$

Implements Combiner.

Definition at line 603 of file Combiner.C.

 double LinearVarianceCombiner::TermVar ( double guess, const Result & r ) const
inlinevirtual

Calculate the contribution variance to the $$\chi^2$$ with the guess $$x'$$.

$V(x') = V + V' (x' - x)$

Parameters
 guess Current guess $$x'$$ r Observation
Returns
$$v(x')$$

Implements Combiner.

Definition at line 638 of file Combiner.C.

 double LinearVarianceCombiner::W ( const Result & r ) const
inlinevirtual

Calculate the weight

$w = (V + x V')^2 / (2 V + x V')$

Parameters
 r Observation
Returns
$$W$$

Implements Combiner.

Definition at line 585 of file Combiner.C.

 static double LinearVarianceCombiner::WrapL ( double * xp, double * pp )
inlinestatic

Wrap likely-hood function for ROOT

Parameters
 xp Pointer to independent variables pp Pointer to parameters
Returns
Likely-hood function evaluate at xp

Definition at line 679 of file Combiner.C.

Referenced by DrawResult::MakeF().

The documentation for this struct was generated from the following file: