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[u/mrichter/AliRoot.git] / RALICE / AliMath.h
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d88f97cc 1#ifndef ALIMATH_H
2#define ALIMATH_H
3///////////////////////////////////////////////////////////////////////////
4// Class AliMath
5// Various mathematical tools which may be very convenient while
6// performing physics analysis.
7//
8// Example : Probability of a Chi-squared value
9// =========
10//
11// AliMath M;
12// Float_t chi2=20 ; // The chi-squared value
13// Int_t ndf=12; // The number of degrees of freedom
14// Float_t p=M.Prob(chi2,ndf); // The probability that at least a Chi-squared
15// // value of chi2 will be observed, even for a
16// // correct model
17//
18//--- NvE 14-nov-1998 UU-SAP Utrecht
19///////////////////////////////////////////////////////////////////////////
20
21#include <iostream.h>
22#include <math.h>
23
24#include "TObject.h"
25
26class AliMath : public TObject
27{
28 public:
29 AliMath(); // Default constructor
30 ~AliMath(); // Destructor
31 Float_t Gamma(Float_t z); // Standard gamma function Gamma(z)
32 Float_t Gamma(Float_t a,Float_t x); // Incomplete gamma function P(a,x)
33 Float_t LnGamma(Float_t z); // Compute ln[Gamma(z)]
34 Float_t Erf(Float_t x); // Error function erf(x)
35 Float_t Erfc(Float_t x); // Complementary error function erfc(x)
36 Float_t Prob(Float_t chi2,Int_t ndf); // Compute Chi-squared probability
37
38 protected:
39 Float_t GamSer(Float_t a,Float_t x); // Compute P(a,x) via serial representation
40 Float_t GamCf(Float_t a,Float_t x); // Compute P(a,x) via continued fractions
41
42 ClassDef(AliMath,1) // Class definition to enable ROOT I/O
43
44};
45#endif