MathTools/src/MathUtils.cc

// $Id: MathUtils.cc,v 1.9 2009/07/20 04:55:44 loizides Exp $

#include "MitCommon/MathTools/interface/MathUtils.h"
#include <TError.h>
#include <TH1D.h>
#include <TGraphAsymmErrors.h>
#include "PhysicsTools/RooStatsCms/interface/ClopperPearsonBinomialInterval.h"
#include "PhysicsTools/RooStatsCms/interface/FeldmanCousinsBinomialInterval.h"


ClassImp(mithep::MathUtils)

using namespace mithep;

//--------------------------------------------------------------------------------------------------
Double_t MathUtils::AddInQuadrature(Double_t a, Double_t b)
{
  // Add quantities in quadrature.

  return(TMath::Sqrt(a*a + b*b));
}

//--------------------------------------------------------------------------------------------------
void MathUtils::CalcRatio(Double_t n1, Double_t n2, Double_t &r, Double_t &rlow, Double_t &rup, Int_t type = 0)
{
  // Calculate ratio and lower/upper errors from given values using Bayes.
  
  if (n1>n2) {
    Error("CalcRatio", "First value should be smaller than second: %f > %f", n1, n2);
    r = n1/n2;
    rlow = 0;
    rup  = 0;
    return;
  }

 
  if (n2 >= 1) {
    if (type == 1) {
      r = double(n1) / double(n2);
      
      //compute errors using Feldman-Cousins
      FeldmanCousinsBinomialInterval fc;
      const double alpha = (1-0.682);
      fc.init(alpha);
      fc.calculate(n1, n2);
      rlow = r - fc.lower();
      rup = fc.upper() - r;    
      
    } else if (type == 2) {
      r = double(n1) / double(n2);
      
      ClopperPearsonBinomialInterval cp;
      const double alpha = (1-0.682);
      cp.init(alpha);
      cp.calculate(n1, n2);
      rlow = r - cp.lower();
      rup = cp.upper() - r;
      
    } else {
      TH1D h1("dummy1","",1,1,2);
      h1.SetBinContent(1,n1);
      
      TH1D h2("dummy2","",1,1,2);
      h2.SetBinContent(1,n2);
      
      TGraphAsymmErrors g;
      g.BayesDivide(&h1,&h2);
      r = g.GetY()[0];
      rup = g.GetErrorYhigh(0);
      rlow = g.GetErrorYlow(0);
    } 
  } else {
    r = 0;
    rlow = 0;
    rup  = 0;
  }
}       


//--------------------------------------------------------------------------------------------------
Double_t MathUtils::DeltaPhi(Double_t phi1, Double_t phi2)
{
  // Compute DeltaPhi between two given angles. Results is in [-pi/2,pi/2].

  Double_t dphi = TMath::Abs(phi1-phi2);
  while (dphi>TMath::Pi())
    dphi = TMath::Abs(dphi - TMath::TwoPi());
  return(dphi);
}

//--------------------------------------------------------------------------------------------------
Double_t MathUtils::DeltaR(Double_t phi1, Double_t eta1, Double_t phi2, Double_t eta2)
{
  // Compute DeltaR between two given points in the eta/phi plane.

  Double_t dR = TMath::Sqrt(DeltaR2(phi1,eta1,phi2,eta2));
  return(dR);
}

//--------------------------------------------------------------------------------------------------
Double_t MathUtils::DeltaR2(Double_t phi1, Double_t eta1, Double_t phi2, Double_t eta2)
{
  // Compute DeltaR between two given points in the eta/phi plane.

  Double_t dphi = DeltaPhi(phi1, phi2);
  Double_t deta = eta1-eta2;
  Double_t dR = dphi*dphi + deta*deta;
  return(dR);
}

//--------------------------------------------------------------------------------------------------
Double_t MathUtils::Eta2Theta(Double_t eta) 
{ 
  // Compute theta from given eta value.

  return 2.*TMath::ATan(exp(-eta)); 
}

//--------------------------------------------------------------------------------------------------
Double_t MathUtils::Theta2Eta(Double_t theta) 
{ 
  // Compute eta from given theta value.

  return -TMath::Log(TMath::Tan(theta/2.)); 
}
Revision:	1.10
Committed:	Tue Nov 3 10:28:08 2009 UTC (15 years, 6 months ago) by sixie
Content type:	text/plain
Branch:	MAIN
Changes since 1.9:	+47 -13 lines
Log Message:	Add Clopper Pearson interval, and Feldman Cousins interval calculations to the CalcRatio function
#	User	Rev	Content
1	sixie	1.10	// $Id: MathUtils.cc,v 1.9 2009/07/20 04:55:44 loizides Exp $
2	sixie	1.1
3			#include "MitCommon/MathTools/interface/MathUtils.h"
4	loizides	1.8	#include <TError.h>
5			#include <TH1D.h>
6			#include <TGraphAsymmErrors.h>
7	sixie	1.10	#include "PhysicsTools/RooStatsCms/interface/ClopperPearsonBinomialInterval.h"
8			#include "PhysicsTools/RooStatsCms/interface/FeldmanCousinsBinomialInterval.h"
9
10	sixie	1.1
11	loizides	1.9	ClassImp(mithep::MathUtils)
12
13	loizides	1.3	using namespace mithep;
14	sixie	1.1
15	loizides	1.2	//--------------------------------------------------------------------------------------------------
16	loizides	1.4	Double_t MathUtils::AddInQuadrature(Double_t a, Double_t b)
17	loizides	1.2	{
18	loizides	1.5	// Add quantities in quadrature.
19
20	loizides	1.2	return(TMath::Sqrt(aa + bb));
21			}
22	sixie	1.1
23	loizides	1.2	//--------------------------------------------------------------------------------------------------
24	sixie	1.10	void MathUtils::CalcRatio(Double_t n1, Double_t n2, Double_t &r, Double_t &rlow, Double_t &rup, Int_t type = 0)
25	loizides	1.8	{
26			// Calculate ratio and lower/upper errors from given values using Bayes.
27
28			if (n1>n2) {
29			Error("CalcRatio", "First value should be smaller than second: %f > %f", n1, n2);
30			r = n1/n2;
31			rlow = 0;
32			rup = 0;
33			return;
34			}
35
36	sixie	1.10
37			if (n2 >= 1) {
38			if (type == 1) {
39			r = double(n1) / double(n2);
40
41			//compute errors using Feldman-Cousins
42			FeldmanCousinsBinomialInterval fc;
43			const double alpha = (1-0.682);
44			fc.init(alpha);
45			fc.calculate(n1, n2);
46			rlow = r - fc.lower();
47			rup = fc.upper() - r;
48
49			} else if (type == 2) {
50			r = double(n1) / double(n2);
51
52			ClopperPearsonBinomialInterval cp;
53			const double alpha = (1-0.682);
54			cp.init(alpha);
55			cp.calculate(n1, n2);
56			rlow = r - cp.lower();
57			rup = cp.upper() - r;
58
59			} else {
60			TH1D h1("dummy1","",1,1,2);
61			h1.SetBinContent(1,n1);
62
63			TH1D h2("dummy2","",1,1,2);
64			h2.SetBinContent(1,n2);
65
66			TGraphAsymmErrors g;
67			g.BayesDivide(&h1,&h2);
68			r = g.GetY()[0];
69			rup = g.GetErrorYhigh(0);
70			rlow = g.GetErrorYlow(0);
71			}
72			} else {
73			r = 0;
74			rlow = 0;
75			rup = 0;
76			}
77			}
78	loizides	1.8
79
80			//--------------------------------------------------------------------------------------------------
81	loizides	1.4	Double_t MathUtils::DeltaPhi(Double_t phi1, Double_t phi2)
82	sixie	1.1	{
83	loizides	1.5	// Compute DeltaPhi between two given angles. Results is in [-pi/2,pi/2].
84
85	loizides	1.4	Double_t dphi = TMath::Abs(phi1-phi2);
86			while (dphi>TMath::Pi())
87			dphi = TMath::Abs(dphi - TMath::TwoPi());
88			return(dphi);
89	sixie	1.1	}
90
91	loizides	1.2	//--------------------------------------------------------------------------------------------------
92	loizides	1.4	Double_t MathUtils::DeltaR(Double_t phi1, Double_t eta1, Double_t phi2, Double_t eta2)
93			{
94	loizides	1.5	// Compute DeltaR between two given points in the eta/phi plane.
95
96	loizides	1.7	Double_t dR = TMath::Sqrt(DeltaR2(phi1,eta1,phi2,eta2));
97			return(dR);
98			}
99
100			//--------------------------------------------------------------------------------------------------
101			Double_t MathUtils::DeltaR2(Double_t phi1, Double_t eta1, Double_t phi2, Double_t eta2)
102			{
103			// Compute DeltaR between two given points in the eta/phi plane.
104
105	loizides	1.4	Double_t dphi = DeltaPhi(phi1, phi2);
106			Double_t deta = eta1-eta2;
107	loizides	1.7	Double_t dR = dphidphi + detadeta;
108	sixie	1.1	return(dR);
109			}
110
111	loizides	1.2	//--------------------------------------------------------------------------------------------------
112	loizides	1.4	Double_t MathUtils::Eta2Theta(Double_t eta)
113	loizides	1.2	{
114	loizides	1.5	// Compute theta from given eta value.
115
116	loizides	1.2	return 2.*TMath::ATan(exp(-eta));
117	sixie	1.1	}
118
119	loizides	1.2	//--------------------------------------------------------------------------------------------------
120	loizides	1.4	Double_t MathUtils::Theta2Eta(Double_t theta)
121	loizides	1.2	{
122	loizides	1.5	// Compute eta from given theta value.
123
124	loizides	1.2	return -TMath::Log(TMath::Tan(theta/2.));
125	sixie	1.1	}