| 1 | #ifndef _CENTROID_HH_
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| 2 | #define _CENTROID_HH_
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| 3 |
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| 4 | //----------------------------------------------------------------------
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| 5 | // This file distributed with FastJet has been obtained from
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| 6 | // http://www.pa.msu.edu/~huston/Les_Houches_2005/JetClu+Midpoint-StandAlone.tgz
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| 7 | //
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| 8 | // Permission to distribute it with FastJet has been granted by Joey
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| 9 | // Huston (see the COPYING file in the main FastJet directory for
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| 10 | // details).
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| 11 | // Changes from the original file are listed below.
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| 12 | //----------------------------------------------------------------------
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| 13 |
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| 14 | // History of changes compared to the original Centroid.hh file
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| 15 | //
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| 16 | // 2009-01-17 Gregory Soyez <soyez@fastjet.fr>
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| 17 | //
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| 18 | // * put the code in the fastjet::cdf namespace
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| 19 | //
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| 20 | // 2008-01-15 Gregory Soyez <soyez@fastjet.fr>
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| 21 | //
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| 22 | // * fixed issues with compilation under VC (definition of M_PI)
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| 23 | //
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| 24 | // 2006-09-24 Gavin Salam <salam@lpthe.jussieu.fr>
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| 25 | //
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| 26 | // * added JetClu+MidPoint to FastJet
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| 27 |
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| 28 | #include <cmath>
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| 29 |
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| 30 | #ifndef M_PI
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| 31 | #define M_PI 3.141592653589793238462643383279502884197
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| 32 | #endif
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| 33 |
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| 34 | #include <fastjet/internal/base.hh>
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| 35 |
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| 36 | FASTJET_BEGIN_NAMESPACE
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| 37 |
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| 38 | namespace cdf{
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| 39 |
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| 40 | class Centroid
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| 41 | {
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| 42 | public:
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| 43 |
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| 44 | double Et,eta,phi;
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| 45 |
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| 46 | Centroid(): Et(0), eta(0), phi(0) {}
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| 47 | Centroid(double centroidEt, double centroidEta, double centroidPhi): Et(centroidEt), eta(centroidEta), phi(centroidPhi) {}
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| 48 | Centroid(const Centroid& c): Et(c.Et), eta(c.eta), phi(c.phi) {}
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| 49 | void add(Centroid c)
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| 50 | {
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| 51 | double newEt = Et + c.Et;
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| 52 | eta = (Et*eta + c.Et*c.eta)/newEt;
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| 53 | double dPhi = c.phi - phi;
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| 54 | if(dPhi > M_PI)
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| 55 | dPhi -= 2*M_PI;
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| 56 | else if(dPhi < -M_PI)
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| 57 | dPhi += 2*M_PI;
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| 58 | phi += dPhi*c.Et/newEt;
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| 59 | while(phi < 0)
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| 60 | phi += 2*M_PI;
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| 61 | while(phi >= 2*M_PI)
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| 62 | phi -= 2*M_PI;
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| 63 | Et = newEt;
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| 64 | }
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| 65 | void subtract(Centroid c)
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| 66 | {
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| 67 | double newEt = Et - c.Et;
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| 68 | eta = (Et*eta - c.Et*c.eta)/newEt;
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| 69 | double dPhi = c.phi - phi;
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| 70 | if(dPhi > M_PI)
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| 71 | dPhi -= 2*M_PI;
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| 72 | else if(dPhi < -M_PI)
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| 73 | dPhi += 2*M_PI;
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| 74 | phi -= dPhi*c.Et/newEt;
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| 75 | while(phi < 0)
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| 76 | phi += 2*M_PI;
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| 77 | while(phi >= 2*M_PI)
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| 78 | phi -= 2*M_PI;
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| 79 | Et = newEt;
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| 80 | }
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| 81 | bool isEqual(Centroid c)
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| 82 | {
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| 83 | return Et == c.Et && eta == c.eta && phi == c.phi;
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| 84 | }
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| 85 | };
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| 86 |
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| 87 | } // namespace cdf
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| 88 |
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| 89 | FASTJET_END_NAMESPACE
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| 90 |
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| 91 | #endif
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