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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