FitUtils Namespace Reference

Classes
class	CrystalBallFunctionObject

Enumerations
enum	ResolutionType { CBFunctionMomenta , CBGaussianPart }

Functions
TF1 *	getCrystalBallFunction (TH1 *hist, Bool_t reversed)
	Obtain a CrystalBall fitting function based on a given histogram. More...
TF1 *	getCrystalBallFunction (TH1 *hist)
	Obtain best CrystalBall function (original or reversed) that fits the histogram. More...
TVector2	getCrystalBallMean (TF1 *cball)
	Calculate Crystal Ball function mean value. More...
TVector2	getCrystalBallDispersion (TF1 *cball)
	Calculate Crystal Ball dispersion (standard deviation) value. More...
TF1 *	getCrystalBallGaussComponent (TF1 *cball)
	Get gaussian part of the crystal ball function. More...
TVector2	getCrystalBallResolution (TF1 *cball, ResolutionType rt=CBFunctionMomenta)
	Calculate Crystal Ball resolution value (standard deviation / mean). More...
TVector2	evalResolution (Double_t mean, Double_t meanErr, Double_t std, Double_t stdErr)
	Calculate resolution of a distribution with given standard deviation and mean. More...

Detailed Description

Implementation of a Crystal Ball function in ROOT. Supports regular and reversed crystal ball functions.

Enumeration Type Documentation

ResolutionType

enum FitUtils::ResolutionType

Enum defines how to calculate Crystall Ball function mean, dispersion and resolution.

Enumerator
CBFunctionMomenta	Based on the Crystal Ball function momenta
CBGaussianPart	Based on Gaussian part of the Crystal Ball function sigma/mean

Function Documentation

evalResolution()

TVector2 FitUtils::evalResolution	(	Double_t	mean,
		Double_t	meanErr,
		Double_t	std,
		Double_t	stdErr
	)

Calculate resolution of a distribution with given standard deviation and mean.

Parameters

mean	distribution mean.
meanErr	distribution mean error.
std	distribution standard deviation.
stdErr	distribution standard deviation error.

Returns

TVector2 resolution value and error.

getCrystalBallDispersion()

TVector2 FitUtils::getCrystalBallDispersion

(

TF1 *

cball

)

Calculate Crystal Ball dispersion (standard deviation) value.

Parameters

cball	Crystal ball function.
reversed	type of the crystal ball function.

Returns

TVector2 dispersion value and error.

getCrystalBallFunction() [1/2]

TF1 * FitUtils::getCrystalBallFunction

(

TH1 *

hist

)

Obtain best CrystalBall function (original or reversed) that fits the histogram.

Function fits the histogram with both crystal ball functions and determines which one provides the best fit.

Parameters

hist	histogram to be fitted.

Returns

original or reversed crystal ball function.

getCrystalBallFunction() [2/2]

TF1 * FitUtils::getCrystalBallFunction	(	TH1 *	hist,
		Bool_t	reversed
	)

Obtain a CrystalBall fitting function based on a given histogram.

Function sets corresponding Crystal GBall function parameters based on the shape of the histogram. User can immediately do the fit.

Parameters

hist	histogram to be fitted.
reversed	set if Crystal Ball function is reversed or not. Default is kFALSE.

Returns

ROOT function ready for fitting.

getCrystalBallGaussComponent()

TF1 * FitUtils::getCrystalBallGaussComponent

(

TF1 *

cball

)

Get gaussian part of the crystal ball function.

Parameters

cball

Crystal ball function.

Returns

TF1* gaussian function.

getCrystalBallMean()

TVector2 FitUtils::getCrystalBallMean

(

TF1 *

cball

)

Calculate Crystal Ball function mean value.

Parameters

cball	Crystal ball function.
reversed	type of the crystal ball function.

Returns

TVector2 mean value and error.

getCrystalBallResolution()

TVector2 FitUtils::getCrystalBallResolution	(	TF1 *	cball,
		ResolutionType	rt = CBFunctionMomenta
	)

Calculate Crystal Ball resolution value (standard deviation / mean).

Parameters

cball

Crystal ball function.

Returns

TVector2 resolution value and error.