1 | #ifndef INLINE_MATHS |
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2 | #define INLINE_MATHS |
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3 | |
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4 | // This file is distributed with FastJet under the terms of the GNU |
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5 | // General Public License (v2). Permission to do so has been granted |
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6 | // by Lars Sonnenschein and the D0 collaboration (see COPYING for |
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7 | // details) |
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8 | // |
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9 | // History of changes in FastJet compared tothe original version of |
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10 | // inline_math.h |
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11 | // |
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12 | // 2011-12-13 Gregory Soyez <soyez@fastjet.fr> |
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13 | // |
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14 | // * added license information |
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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::d0 namespace |
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19 | |
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20 | #include <cerrno> |
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21 | |
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22 | #include <fastjet/internal/base.hh> |
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23 | |
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24 | FASTJET_BEGIN_NAMESPACE |
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25 | |
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26 | namespace d0{ |
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27 | |
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28 | namespace inline_maths { |
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29 | |
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30 | const double PI = fabs(acos(-1.)); |
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31 | |
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32 | const double TWOPI = 2*PI; |
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33 | |
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34 | |
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35 | inline double sqr(double a) { |
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36 | return a*a; |
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37 | } |
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38 | |
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39 | |
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40 | |
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41 | inline double min(double a, double b) { |
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42 | return (a < b) ? a : b; |
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43 | } |
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44 | |
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45 | |
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46 | |
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47 | inline double delta_phi(double phi1, double phi2) { |
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48 | return min( double(fabs(phi1-phi2)), double(2.*PI-fabs(phi1-phi2)) ); |
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49 | } |
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50 | |
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51 | |
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52 | |
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53 | inline double phi(double px, double py) { |
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54 | return atan2(py, px); |
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55 | } |
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56 | |
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57 | |
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58 | |
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59 | inline double y(double E, double pz) { |
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60 | errno=0; |
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61 | double y; |
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62 | //cout << "inline_maths: "; |
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63 | if (fabs(E-pz) == 0.) { |
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64 | // cout << "Error in header mathe.h: division by 0 in function eta!" << " p=" << p << " pz=" << pz << endl; |
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65 | // exit(721); |
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66 | errno=721; |
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67 | y = 99999.; |
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68 | } |
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69 | else { |
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70 | y = 0.5*log((E+pz)/(E-pz)); |
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71 | } |
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72 | //cout << "y: E=" << E << " pz=" << pz << " y=" << y << endl; |
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73 | return y; |
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74 | } |
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75 | |
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76 | |
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77 | } //end usename inline_maths |
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78 | |
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79 | |
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80 | } // namespace d0 |
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81 | |
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82 | FASTJET_END_NAMESPACE |
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83 | |
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84 | #endif |
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