[1835] | 1 | /* -*- C++ -*- |
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| 2 | * lemon/tolerance.h - Part of LEMON, a generic C++ optimization library |
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| 3 | * |
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[1875] | 4 | * Copyright (C) 2006 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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[1835] | 5 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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| 6 | * |
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| 7 | * Permission to use, modify and distribute this software is granted |
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| 8 | * provided that this copyright notice appears in all copies. For |
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| 9 | * precise terms see the accompanying LICENSE file. |
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| 10 | * |
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| 11 | * This software is provided "AS IS" with no warranty of any kind, |
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| 12 | * express or implied, and with no claim as to its suitability for any |
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| 13 | * purpose. |
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| 14 | * |
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| 15 | */ |
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| 16 | |
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| 17 | #ifndef LEMON_TOLERANCE_H |
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| 18 | #define LEMON_TOLERANCE_H |
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| 19 | |
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| 20 | ///\ingroup misc |
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| 21 | ///\file |
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| 22 | ///\brief A basic tool to handle the anomalies of calculation with |
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| 23 | ///floating point numbers. |
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| 24 | /// |
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| 25 | ///\todo It should be in a module like "Basic tools" |
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| 26 | |
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| 27 | |
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| 28 | namespace lemon { |
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| 29 | |
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| 30 | /// \addtogroup misc |
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| 31 | /// @{ |
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| 32 | |
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| 33 | ///\brief A class to provide a basic way to |
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| 34 | ///handle the comparison of numbers that are obtained |
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| 35 | ///as a result of a probably inexact computation. |
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| 36 | /// |
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| 37 | ///Tolerance is a class to provide a basic way to |
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| 38 | ///handle the comparison of numbers that are obtained |
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| 39 | ///as a result of a probably inexact computation. |
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| 40 | /// |
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| 41 | ///This is an abstract class, it should be specialized for all numerical |
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| 42 | ///data types. These specialized classes like \ref Tolerance<double> |
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| 43 | ///may offer additional tuning parameters. |
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| 44 | /// |
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| 45 | ///\sa Tolerance<float> |
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| 46 | ///\sa Tolerance<double> |
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| 47 | ///\sa Tolerance<int> |
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| 48 | ///\sa Tolerance<long long int> |
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| 49 | |
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| 50 | template<class T> |
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| 51 | class Tolerance |
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| 52 | { |
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| 53 | public: |
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| 54 | typedef T Value; |
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| 55 | |
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| 56 | ///\name Comparisons |
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| 57 | ///The concept is that these bool functions return with \c true only if |
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| 58 | ///the related comparisons hold even if some numerical error appeared |
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| 59 | ///during the computations. |
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| 60 | |
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| 61 | ///@{ |
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| 62 | |
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| 63 | ///Returns \c true if \c a is \e surely strictly less than \c b |
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| 64 | static bool less(Value a,Value b) {return false;} |
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| 65 | ///Returns \c true if \c a is \e surely different from \c b |
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| 66 | static bool different(Value a,Value b) {return false;} |
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| 67 | ///Returns \c true if \c a is \e surely positive |
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| 68 | static bool positive(Value a) {return false;} |
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| 69 | ///Returns \c true if \c a is \e surely negative |
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| 70 | static bool negative(Value a) {return false;} |
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| 71 | ///Returns \c true if \c a is \e surely non-zero |
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| 72 | static bool nonZero(Value a) {return false;} |
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| 73 | |
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| 74 | ///@} |
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| 75 | |
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| 76 | ///Returns the zero value. |
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| 77 | static Value zero() {return T();} |
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| 78 | |
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| 79 | // static bool finite(Value a) {} |
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| 80 | // static Value big() {} |
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| 81 | // static Value negativeBig() {} |
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| 82 | }; |
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| 83 | |
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| 84 | |
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| 85 | ///Double specialization of \ref Tolerance. |
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| 86 | |
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| 87 | ///Double specialization of \ref Tolerance. |
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| 88 | ///\sa Tolerance |
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| 89 | ///\relates Tolerance |
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| 90 | template<> |
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| 91 | class Tolerance<double> |
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| 92 | { |
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| 93 | static double def_epsilon; |
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| 94 | double _epsilon; |
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| 95 | public: |
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| 96 | ///\e |
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| 97 | typedef double Value; |
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| 98 | |
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| 99 | ///Constructor setting the epsilon tolerance to the default value. |
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| 100 | Tolerance() : _epsilon(def_epsilon) {} |
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| 101 | ///Constructor setting the epsilon tolerance. |
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| 102 | Tolerance(double e) : _epsilon(e) {} |
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| 103 | |
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| 104 | ///Return the epsilon value. |
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| 105 | Value epsilon() {return _epsilon;} |
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| 106 | ///Set the epsilon value. |
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| 107 | void epsilon(Value e) {_epsilon=e;} |
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| 108 | |
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| 109 | ///Return the default epsilon value. |
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| 110 | static Value defaultEpsilon() {return def_epsilon;} |
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| 111 | ///Set the default epsilon value. |
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| 112 | static void defaultEpsilon(Value e) {def_epsilon=e;} |
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| 113 | |
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| 114 | ///\name Comparisons |
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| 115 | ///See class Tolerance for more details. |
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| 116 | |
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| 117 | ///@{ |
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| 118 | |
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| 119 | ///Returns \c true if \c a is \e surely strictly less than \c b |
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| 120 | bool less(Value a,Value b) {return a+_epsilon<b;} |
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| 121 | ///Returns \c true if \c a is \e surely different from \c b |
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| 122 | bool different(Value a,Value b) { return less(a,b)||less(b,a); } |
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| 123 | ///Returns \c true if \c a is \e surely positive |
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| 124 | bool positive(Value a) { return _epsilon<a; } |
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| 125 | ///Returns \c true if \c a is \e surely negative |
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| 126 | bool negative(Value a) { return -_epsilon>a; } |
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| 127 | ///Returns \c true if \c a is \e surely non-zero |
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| 128 | Value nonZero(Value a) { return positive(a)||negative(a); }; |
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| 129 | |
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| 130 | ///@} |
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| 131 | |
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| 132 | ///Returns zero |
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| 133 | static Value zero() {return 0;} |
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| 134 | }; |
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| 135 | |
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| 136 | ///Float specialization of \ref Tolerance. |
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| 137 | |
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| 138 | ///Float specialization of \ref Tolerance. |
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| 139 | ///\sa Tolerance |
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| 140 | ///\relates Tolerance |
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| 141 | template<> |
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| 142 | class Tolerance<float> |
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| 143 | { |
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| 144 | static float def_epsilon; |
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| 145 | float _epsilon; |
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| 146 | public: |
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| 147 | ///\e |
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| 148 | typedef float Value; |
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| 149 | |
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| 150 | ///Constructor setting the epsilon tolerance to the default value. |
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| 151 | Tolerance() : _epsilon(def_epsilon) {} |
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| 152 | ///Constructor setting the epsilon tolerance. |
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| 153 | Tolerance(float e) : _epsilon(e) {} |
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| 154 | |
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| 155 | ///Return the epsilon value. |
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| 156 | Value epsilon() {return _epsilon;} |
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| 157 | ///Set the epsilon value. |
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| 158 | void epsilon(Value e) {_epsilon=e;} |
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| 159 | |
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| 160 | ///Return the default epsilon value. |
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| 161 | static Value defaultEpsilon() {return def_epsilon;} |
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| 162 | ///Set the default epsilon value. |
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| 163 | static void defaultEpsilon(Value e) {def_epsilon=e;} |
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| 164 | |
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| 165 | ///\name Comparisons |
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| 166 | ///See class Tolerance for more details. |
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| 167 | |
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| 168 | ///@{ |
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| 169 | |
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| 170 | ///Returns \c true if \c a is \e surely strictly less than \c b |
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| 171 | bool less(Value a,Value b) {return a+_epsilon<b;} |
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| 172 | ///Returns \c true if \c a is \e surely different from \c b |
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| 173 | bool different(Value a,Value b) { return less(a,b)||less(b,a); } |
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| 174 | ///Returns \c true if \c a is \e surely positive |
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| 175 | bool positive(Value a) { return _epsilon<a; } |
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| 176 | ///Returns \c true if \c a is \e surely negative |
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| 177 | bool negative(Value a) { return -_epsilon>a; } |
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| 178 | ///Returns \c true if \c a is \e surely non-zero |
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| 179 | Value nonZero(Value a) { return positive(a)||negative(a); }; |
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| 180 | |
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| 181 | ///@} |
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| 182 | |
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| 183 | ///Returns zero |
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| 184 | static Value zero() {return 0;} |
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| 185 | }; |
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| 186 | |
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| 187 | ///Integer specialization of \ref Tolerance. |
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| 188 | |
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| 189 | ///Integer specialization of \ref Tolerance. |
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| 190 | ///\sa Tolerance |
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| 191 | template<> |
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| 192 | class Tolerance<int> |
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| 193 | { |
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| 194 | public: |
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| 195 | ///\e |
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| 196 | typedef int Value; |
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| 197 | |
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| 198 | ///\name Comparisons |
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| 199 | ///See \ref Tolerance for more details. |
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| 200 | |
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| 201 | ///@{ |
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| 202 | |
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| 203 | ///Returns \c true if \c a is \e surely strictly less than \c b |
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| 204 | static bool less(Value a,Value b) { return a<b;} |
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| 205 | ///Returns \c true if \c a is \e surely different from \c b |
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| 206 | static bool different(Value a,Value b) { return a!=b; } |
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| 207 | ///Returns \c true if \c a is \e surely positive |
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| 208 | static bool positive(Value a) { return 0<a; } |
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| 209 | ///Returns \c true if \c a is \e surely negative |
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| 210 | static bool negative(Value a) { return 0>a; } |
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| 211 | ///Returns \c true if \c a is \e surely non-zero |
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| 212 | static Value nonZero(Value a) { return a!=0;}; |
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| 213 | |
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| 214 | ///@} |
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| 215 | |
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| 216 | ///Returns zero |
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| 217 | static Value zero() {return 0;} |
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| 218 | }; |
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| 219 | |
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| 220 | ///Long long integer specialization of \ref Tolerance. |
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| 221 | |
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| 222 | ///Long long integer specialization of \ref Tolerance. |
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| 223 | ///\sa Tolerance |
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| 224 | template<> |
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| 225 | class Tolerance<long long int> |
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| 226 | { |
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| 227 | public: |
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| 228 | ///\e |
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| 229 | typedef long long int Value; |
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| 230 | |
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| 231 | ///\name Comparisons |
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| 232 | ///See \ref Tolerance for more details. |
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| 233 | |
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| 234 | ///@{ |
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| 235 | |
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| 236 | ///Returns \c true if \c a is \e surely strictly less than \c b |
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| 237 | static bool less(Value a,Value b) { return a<b;} |
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| 238 | ///Returns \c true if \c a is \e surely different from \c b |
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| 239 | static bool different(Value a,Value b) { return a!=b; } |
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| 240 | ///Returns \c true if \c a is \e surely positive |
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| 241 | static bool positive(Value a) { return 0<a; } |
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| 242 | ///Returns \c true if \c a is \e surely negative |
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| 243 | static bool negative(Value a) { return 0>a; } |
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| 244 | ///Returns \c true if \c a is \e surely non-zero |
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| 245 | static Value nonZero(Value a) { return a!=0;}; |
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| 246 | |
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| 247 | ///@} |
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| 248 | |
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| 249 | ///Returns zero |
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| 250 | static Value zero() {return 0;} |
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| 251 | }; |
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| 252 | |
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| 253 | /// @} |
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| 254 | |
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| 255 | } //namespace lemon |
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| 256 | |
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| 257 | #endif //LEMON_TOLERANCE_H |
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