| 1 | // -*- C++ -*-
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| 2 | //
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| 3 | // This file is part of HepMC
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| 4 | // Copyright (C) 2014-2020 The HepMC collaboration (see AUTHORS for details)
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| 5 | //
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| 6 | #ifndef HEPMC3_UNITS_H
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| 7 | #define HEPMC3_UNITS_H
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| 8 | /**
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| 9 | * @file Units.h
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| 10 | * @brief Definition of \b class Units
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| 11 | *
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| 12 | * @class HepMC3::Units
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| 13 | * @brief Stores units-related enums and conversion functions
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| 14 | *
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| 15 | * Manages units used by HepMC::GenEvent
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| 16 | *
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| 17 | */
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| 18 | #include <string>
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| 19 | #include "HepMC3/Errors.h"
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| 20 | #include "HepMC3/Setup.h"
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| 21 | #include "HepMC3/FourVector.h"
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| 22 |
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| 23 | namespace HepMC3 {
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| 24 |
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| 25 |
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| 26 | class Units {
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| 27 | public:
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| 28 | /** @brief Momentum units */
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| 29 | enum MomentumUnit { MEV, GEV };
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| 30 |
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| 31 | /** @brief Position units */
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| 32 | enum LengthUnit { MM, CM };
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| 33 |
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| 34 | public:
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| 35 | /** @brief Get momentum unit based on its name*/
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| 36 | static MomentumUnit momentum_unit( const std::string& name ) {
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| 37 | if( name.compare(0,3,"GEV") == 0 ) return GEV;
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| 38 | if( name.compare(0,3,"MEV") == 0 ) return MEV;
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| 39 |
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| 40 | HEPMC3_ERROR("Units::momentum_unit: unrecognised unit name: '" << name <<"', setting to GEV" )
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| 41 |
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| 42 | return GEV;
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| 43 | }
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| 44 |
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| 45 | /** @brief Get length unit based on its name*/
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| 46 | static LengthUnit length_unit( const std::string& name ) {
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| 47 | if( name.compare(0,2,"CM") == 0 ) return CM;
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| 48 | if( name.compare(0,2,"MM") == 0 ) return MM;
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| 49 |
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| 50 | HEPMC3_ERROR("Units::length_unit: unrecognised unit name: '" << name <<"', setting to CM" )
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| 51 |
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| 52 | return CM;
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| 53 | }
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| 54 |
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| 55 | /** @brief Get name of momentum unit */
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| 56 | static std::string name( MomentumUnit u ) {
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| 57 | switch(u) {
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| 58 | case MEV:
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| 59 | return "MEV";
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| 60 | case GEV:
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| 61 | return "GEV";
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| 62 | }
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| 63 |
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| 64 | return "<UNDEFINED>";
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| 65 | }
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| 66 |
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| 67 | /** @brief Get name of length unit */
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| 68 | static std::string name( LengthUnit u ) {
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| 69 | switch(u) {
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| 70 | case MM:
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| 71 | return "MM";
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| 72 | case CM:
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| 73 | return "CM";
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| 74 | }
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| 75 |
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| 76 | return "<UNDEFINED>";
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| 77 | }
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| 78 |
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| 79 | /** @brief Convert FourVector to different momentum unit */
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| 80 | template <typename T>
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| 81 | static void convert( T &m, MomentumUnit from, MomentumUnit to ) {
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| 82 | if( from == to ) return;
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| 83 |
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| 84 | if( from == GEV ) {
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| 85 | // GEV -> MEV
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| 86 | m *= 1000.;
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| 87 | }
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| 88 | else if( from == MEV ) {
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| 89 | // MEV -> GEV
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| 90 | m *= 0.001;
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| 91 | }
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| 92 | }
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| 93 |
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| 94 | /** @brief Convert FourVector to different length unit */
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| 95 | template <typename T>
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| 96 | static void convert( T &m, LengthUnit from, LengthUnit to ) {
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| 97 | if( from == to ) return;
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| 98 |
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| 99 | if( from == CM ) {
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| 100 | // CM -> MM
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| 101 | m *= 10.0;
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| 102 | }
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| 103 | else if( from == MM ) {
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| 104 | // MM -> CM
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| 105 | m *= 0.1;
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| 106 | }
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| 107 | }
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| 108 |
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| 109 | };
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| 110 |
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| 111 | } // namespace HepMC3
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| 112 |
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| 113 | #endif
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