MathTools/src/MathUtils.cc

// $Id: MathUtils.cc,v 1.7 2009/05/11 08:23:06 loizides Exp $

#include "MitCommon/MathTools/interface/MathUtils.h"
#include <TError.h>
#include <TH1D.h>
#include <TGraphAsymmErrors.h>

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)
{
  // 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;
  }

  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);
}       

//--------------------------------------------------------------------------------------------------
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:	1.8
Committed:	Wed Jun 24 14:51:05 2009 UTC (15 years, 10 months ago) by loizides
Content type:	text/plain
Branch:	MAIN
Changes since 1.7:	+30 -1 lines
Log Message:	Added CalcRatio using BayesDivide
#	User	Rev	Content
1	loizides	1.8	// $Id: MathUtils.cc,v 1.7 2009/05/11 08:23:06 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	1.1
8	loizides	1.3	using namespace mithep;
9	sixie	1.1
10	loizides	1.2	//--------------------------------------------------------------------------------------------------
11	loizides	1.4	Double_t MathUtils::AddInQuadrature(Double_t a, Double_t b)
12	loizides	1.2	{
13	loizides	1.5	// Add quantities in quadrature.
14
15	loizides	1.2	return(TMath::Sqrt(aa + bb));
16			}
17	sixie	1.1
18	loizides	1.2	//--------------------------------------------------------------------------------------------------
19	loizides	1.8	void MathUtils::CalcRatio(Double_t n1, Double_t n2, Double_t &r, Double_t &rlow, Double_t &rup)
20			{
21			// Calculate ratio and lower/upper errors from given values using Bayes.
22
23			if (n1>n2) {
24			Error("CalcRatio", "First value should be smaller than second: %f > %f", n1, n2);
25			r = n1/n2;
26			rlow = 0;
27			rup = 0;
28			return;
29			}
30
31			TH1D h1("dummy1","",1,1,2);
32			h1.SetBinContent(1,n1);
33
34			TH1D h2("dummy2","",1,1,2);
35			h2.SetBinContent(1,n2);
36
37			TGraphAsymmErrors g;
38			g.BayesDivide(&h1,&h2);
39			r = g.GetY()[0];
40			rup = g.GetErrorYhigh(0);
41			rlow = g.GetErrorYlow(0);
42			}
43
44			//--------------------------------------------------------------------------------------------------
45	loizides	1.4	Double_t MathUtils::DeltaPhi(Double_t phi1, Double_t phi2)
46	sixie	1.1	{
47	loizides	1.5	// Compute DeltaPhi between two given angles. Results is in [-pi/2,pi/2].
48
49	loizides	1.4	Double_t dphi = TMath::Abs(phi1-phi2);
50			while (dphi>TMath::Pi())
51			dphi = TMath::Abs(dphi - TMath::TwoPi());
52			return(dphi);
53	sixie	1.1	}
54
55	loizides	1.2	//--------------------------------------------------------------------------------------------------
56	loizides	1.4	Double_t MathUtils::DeltaR(Double_t phi1, Double_t eta1, Double_t phi2, Double_t eta2)
57			{
58	loizides	1.5	// Compute DeltaR between two given points in the eta/phi plane.
59
60	loizides	1.7	Double_t dR = TMath::Sqrt(DeltaR2(phi1,eta1,phi2,eta2));
61			return(dR);
62			}
63
64			//--------------------------------------------------------------------------------------------------
65			Double_t MathUtils::DeltaR2(Double_t phi1, Double_t eta1, Double_t phi2, Double_t eta2)
66			{
67			// Compute DeltaR between two given points in the eta/phi plane.
68
69	loizides	1.4	Double_t dphi = DeltaPhi(phi1, phi2);
70			Double_t deta = eta1-eta2;
71	loizides	1.7	Double_t dR = dphidphi + detadeta;
72	sixie	1.1	return(dR);
73			}
74
75	loizides	1.2	//--------------------------------------------------------------------------------------------------
76	loizides	1.4	Double_t MathUtils::Eta2Theta(Double_t eta)
77	loizides	1.2	{
78	loizides	1.5	// Compute theta from given eta value.
79
80	loizides	1.2	return 2.*TMath::ATan(exp(-eta));
81	sixie	1.1	}
82
83	loizides	1.2	//--------------------------------------------------------------------------------------------------
84	loizides	1.4	Double_t MathUtils::Theta2Eta(Double_t theta)
85	loizides	1.2	{
86	loizides	1.5	// Compute eta from given theta value.
87
88	loizides	1.2	return -TMath::Log(TMath::Tan(theta/2.));
89	sixie	1.1	}