MathTools/src/MathUtils.cc

// $Id: MathUtils.cc,v 1.10 2009/11/03 10:28:08 sixie 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 various methods, dependent on type:
  //  0: Bayes
  //  1: Feldman-Cousins
  //  2: Clopper-Pearson
  
  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) {
      //compute errors using Feldman-Cousins
      r = double(n1) / double(n2);
      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) {
      //compute errors using Clopper-Pearson
      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 {
      //compute using Bayes
      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:	1.11
Committed:	Wed Nov 4 12:44:33 2009 UTC (15 years, 6 months ago) by loizides
Content type:	text/plain
Branch:	MAIN
CVS Tags:	Mit_025c_branch2, Mit_025c_branch1, Mit_025c_branch0, Mit_025c, Mit_025b, Mit_025a, Mit_025, Mit_025pre2, Mit_024b, Mit_025pre1, Mit_024a, Mit_024, Mit_023, Mit_022a, Mit_022, Mit_020d, TMit_020d, Mit_020c, Mit_021, Mit_021pre2, Mit_021pre1, Mit_020b, Mit_020a, Mit_020, Mit_020pre1, Mit_018, Mit_017, Mit_017pre3, Mit_017pre2, Mit_017pre1, V07-05-00, Mit_016, Mit_015b, Mit_015a, Mit_015, Mit_014e, Mit_014d, Mit_014c, Mit_014b, ConvRejection-10-06-09, Mit_014a, Mit_014, Mit_014pre3, Mit_014pre2, Mit_014pre1, Mit_013d, Mit_013c, Mit_013b, Mit_013a, Mit_013, Mit_013pre1, Mit_012i, Mit_012g, Mit_012f, Mit_012e, Mit_012d, Mit_012c, Mit_012b, Mit_012a, Mit_012
Branch point for:	Mit_025c_branch
Changes since 1.10:	+8 -6 lines
Log Message:	Improved docu
#	User	Rev	Content
1	loizides	1.11	// $Id: MathUtils.cc,v 1.10 2009/11/03 10:28:08 sixie 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	loizides	1.11	// Calculate ratio and lower/upper errors from given values using various methods, dependent on type:
27			// 0: Bayes
28			// 1: Feldman-Cousins
29			// 2: Clopper-Pearson
30	loizides	1.8
31			if (n1>n2) {
32			Error("CalcRatio", "First value should be smaller than second: %f > %f", n1, n2);
33			r = n1/n2;
34			rlow = 0;
35			rup = 0;
36			return;
37			}
38	sixie	1.10
39			if (n2 >= 1) {
40			if (type == 1) {
41	loizides	1.11	//compute errors using Feldman-Cousins
42	sixie	1.10	r = double(n1) / double(n2);
43			FeldmanCousinsBinomialInterval fc;
44			const double alpha = (1-0.682);
45			fc.init(alpha);
46			fc.calculate(n1, n2);
47			rlow = r - fc.lower();
48			rup = fc.upper() - r;
49
50			} else if (type == 2) {
51	loizides	1.11	//compute errors using Clopper-Pearson
52	sixie	1.10	r = double(n1) / double(n2);
53			ClopperPearsonBinomialInterval cp;
54			const double alpha = (1-0.682);
55			cp.init(alpha);
56			cp.calculate(n1, n2);
57			rlow = r - cp.lower();
58			rup = cp.upper() - r;
59
60			} else {
61	loizides	1.11	//compute using Bayes
62	sixie	1.10	TH1D h1("dummy1","",1,1,2);
63			h1.SetBinContent(1,n1);
64
65			TH1D h2("dummy2","",1,1,2);
66			h2.SetBinContent(1,n2);
67
68			TGraphAsymmErrors g;
69			g.BayesDivide(&h1,&h2);
70			r = g.GetY()[0];
71			rup = g.GetErrorYhigh(0);
72			rlow = g.GetErrorYlow(0);
73			}
74			} else {
75			r = 0;
76			rlow = 0;
77			rup = 0;
78			}
79			}
80	loizides	1.8
81
82			//--------------------------------------------------------------------------------------------------
83	loizides	1.4	Double_t MathUtils::DeltaPhi(Double_t phi1, Double_t phi2)
84	sixie	1.1	{
85	loizides	1.5	// Compute DeltaPhi between two given angles. Results is in [-pi/2,pi/2].
86
87	loizides	1.4	Double_t dphi = TMath::Abs(phi1-phi2);
88			while (dphi>TMath::Pi())
89			dphi = TMath::Abs(dphi - TMath::TwoPi());
90			return(dphi);
91	sixie	1.1	}
92
93	loizides	1.2	//--------------------------------------------------------------------------------------------------
94	loizides	1.4	Double_t MathUtils::DeltaR(Double_t phi1, Double_t eta1, Double_t phi2, Double_t eta2)
95			{
96	loizides	1.5	// Compute DeltaR between two given points in the eta/phi plane.
97
98	loizides	1.7	Double_t dR = TMath::Sqrt(DeltaR2(phi1,eta1,phi2,eta2));
99			return(dR);
100			}
101
102			//--------------------------------------------------------------------------------------------------
103			Double_t MathUtils::DeltaR2(Double_t phi1, Double_t eta1, Double_t phi2, Double_t eta2)
104			{
105			// Compute DeltaR between two given points in the eta/phi plane.
106
107	loizides	1.4	Double_t dphi = DeltaPhi(phi1, phi2);
108			Double_t deta = eta1-eta2;
109	loizides	1.7	Double_t dR = dphidphi + detadeta;
110	sixie	1.1	return(dR);
111			}
112
113	loizides	1.2	//--------------------------------------------------------------------------------------------------
114	loizides	1.4	Double_t MathUtils::Eta2Theta(Double_t eta)
115	loizides	1.2	{
116	loizides	1.5	// Compute theta from given eta value.
117
118	loizides	1.2	return 2.*TMath::ATan(exp(-eta));
119	sixie	1.1	}
120
121	loizides	1.2	//--------------------------------------------------------------------------------------------------
122	loizides	1.4	Double_t MathUtils::Theta2Eta(Double_t theta)
123	loizides	1.2	{
124	loizides	1.5	// Compute eta from given theta value.
125
126	loizides	1.2	return -TMath::Log(TMath::Tan(theta/2.));
127	sixie	1.1	}