lemon/tolerance.h
author Alpar Juttner <alpar@cs.elte.hu>
Sat, 29 Mar 2008 15:49:50 +0000
changeset 111 e47fb28cda5e
parent 49 9a556af88710
child 209 765619b7cbb2
permissions -rw-r--r--
Fix ignoring Emacs backup files
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/* -*- C++ -*-
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 *
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 * This file is a part of LEMON, a generic C++ optimization library
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 *
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 * Copyright (C) 2003-2008
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 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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#ifndef LEMON_TOLERANCE_H
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#define LEMON_TOLERANCE_H
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///\ingroup misc
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///\file
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///\brief A basic tool to handle the anomalies of calculation with
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///floating point numbers.
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///
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///\todo It should be in a module like "Basic tools"
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namespace lemon {
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  /// \addtogroup misc
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  /// @{
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  ///\brief A class to provide a basic way to
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  ///handle the comparison of numbers that are obtained
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  ///as a result of a probably inexact computation.
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  ///
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  ///\ref Tolerance is a class to provide a basic way to
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  ///handle the comparison of numbers that are obtained
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  ///as a result of a probably inexact computation.
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  ///
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  ///This is an abstract class, it should be specialized for all 
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  ///numerical data types. These specialized classes like 
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  ///Tolerance<double> may offer additional tuning parameters.
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  ///
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  ///\sa Tolerance<float>
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  ///\sa Tolerance<double>
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  ///\sa Tolerance<long double>
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  ///\sa Tolerance<int>
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  ///\sa Tolerance<long long int>
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  ///\sa Tolerance<unsigned int>
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  ///\sa Tolerance<unsigned long long int>
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  template<class T>
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  class Tolerance
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  {
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  public:
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    typedef T Value;
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    ///\name Comparisons
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    ///The concept is that these bool functions return \c true only if
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    ///the related comparisons hold even if some numerical error appeared
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    ///during the computations.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    static bool less(Value a,Value b) {return false;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    static bool different(Value a,Value b) {return false;}
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    ///Returns \c true if \c a is \e surely positive
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    static bool positive(Value a) {return false;}
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    ///Returns \c true if \c a is \e surely negative
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    static bool negative(Value a) {return false;}
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    ///Returns \c true if \c a is \e surely non-zero
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    static bool nonZero(Value a) {return false;}
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    ///@}
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    ///Returns the zero value.
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    static Value zero() {return T();}
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    //   static bool finite(Value a) {}
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    //   static Value big() {}
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    //   static Value negativeBig() {}
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  };
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  ///Float specialization of Tolerance.
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  ///Float specialization of Tolerance.
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  ///\sa Tolerance
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  ///\relates Tolerance
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  template<>
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  class Tolerance<float>
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  {
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    static float def_epsilon;
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    float _epsilon;
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  public:
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    ///\e
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    typedef float Value;
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    ///Constructor setting the epsilon tolerance to the default value.
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    Tolerance() : _epsilon(def_epsilon) {}
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    ///Constructor setting the epsilon tolerance to the given value.
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    Tolerance(float e) : _epsilon(e) {}
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    ///Returns the epsilon value.
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    Value epsilon() const {return _epsilon;}
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    ///Sets the epsilon value.
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    void epsilon(Value e) {_epsilon=e;}
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    ///Returns the default epsilon value.
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    static Value defaultEpsilon() {return def_epsilon;}
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    ///Sets the default epsilon value.
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    static void defaultEpsilon(Value e) {def_epsilon=e;}
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    ///\name Comparisons
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    ///See \ref lemon::Tolerance "Tolerance" for more details.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    bool less(Value a,Value b) const {return a+_epsilon<b;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    bool different(Value a,Value b) const { return less(a,b)||less(b,a); }
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    ///Returns \c true if \c a is \e surely positive
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    bool positive(Value a) const { return _epsilon<a; }
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    ///Returns \c true if \c a is \e surely negative
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    bool negative(Value a) const { return -_epsilon>a; }
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    ///Returns \c true if \c a is \e surely non-zero
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    bool nonZero(Value a) const { return positive(a)||negative(a); }
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    ///@}
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    ///Returns zero
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    static Value zero() {return 0;}
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  };
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  ///Double specialization of Tolerance.
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  ///Double specialization of Tolerance.
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  ///\sa Tolerance
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  ///\relates Tolerance
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  template<>
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  class Tolerance<double>
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  {
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    static double def_epsilon;
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    double _epsilon;
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  public:
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    ///\e
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    typedef double Value;
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    ///Constructor setting the epsilon tolerance to the default value.
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    Tolerance() : _epsilon(def_epsilon) {}
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    ///Constructor setting the epsilon tolerance to the given value.
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    Tolerance(double e) : _epsilon(e) {}
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    ///Returns the epsilon value.
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    Value epsilon() const {return _epsilon;}
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    ///Sets the epsilon value.
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    void epsilon(Value e) {_epsilon=e;}
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    ///Returns the default epsilon value.
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    static Value defaultEpsilon() {return def_epsilon;}
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    ///Sets the default epsilon value.
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    static void defaultEpsilon(Value e) {def_epsilon=e;}
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    ///\name Comparisons
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    ///See \ref lemon::Tolerance "Tolerance" for more details.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    bool less(Value a,Value b) const {return a+_epsilon<b;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    bool different(Value a,Value b) const { return less(a,b)||less(b,a); }
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    ///Returns \c true if \c a is \e surely positive
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    bool positive(Value a) const { return _epsilon<a; }
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    ///Returns \c true if \c a is \e surely negative
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    bool negative(Value a) const { return -_epsilon>a; }
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    ///Returns \c true if \c a is \e surely non-zero
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    bool nonZero(Value a) const { return positive(a)||negative(a); }
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    ///@}
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    ///Returns zero
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    static Value zero() {return 0;}
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  };
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  ///Long double specialization of Tolerance.
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  ///Long double specialization of Tolerance.
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  ///\sa Tolerance
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  ///\relates Tolerance
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  template<>
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  class Tolerance<long double>
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  {
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    static long double def_epsilon;
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    long double _epsilon;
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  public:
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    ///\e
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    typedef long double Value;
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    ///Constructor setting the epsilon tolerance to the default value.
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    Tolerance() : _epsilon(def_epsilon) {}
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    ///Constructor setting the epsilon tolerance to the given value.
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    Tolerance(long double e) : _epsilon(e) {}
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    ///Returns the epsilon value.
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    Value epsilon() const {return _epsilon;}
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    ///Sets the epsilon value.
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    void epsilon(Value e) {_epsilon=e;}
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    ///Returns the default epsilon value.
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    static Value defaultEpsilon() {return def_epsilon;}
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    ///Sets the default epsilon value.
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    static void defaultEpsilon(Value e) {def_epsilon=e;}
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    ///\name Comparisons
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    ///See \ref lemon::Tolerance "Tolerance" for more details.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    bool less(Value a,Value b) const {return a+_epsilon<b;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    bool different(Value a,Value b) const { return less(a,b)||less(b,a); }
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    ///Returns \c true if \c a is \e surely positive
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    bool positive(Value a) const { return _epsilon<a; }
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    ///Returns \c true if \c a is \e surely negative
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    bool negative(Value a) const { return -_epsilon>a; }
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    ///Returns \c true if \c a is \e surely non-zero
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    bool nonZero(Value a) const { return positive(a)||negative(a); }
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    ///@}
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    ///Returns zero
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    static Value zero() {return 0;}
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  };
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  ///Integer specialization of Tolerance.
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  ///Integer specialization of Tolerance.
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  ///\sa Tolerance
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  template<>
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  class Tolerance<int>
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  {
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  public:
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    ///\e
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    typedef int Value;
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    ///\name Comparisons
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    ///See \ref lemon::Tolerance "Tolerance" for more details.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    static bool less(Value a,Value b) { return a<b;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    static bool different(Value a,Value b) { return a!=b; }
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    ///Returns \c true if \c a is \e surely positive
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    static bool positive(Value a) { return 0<a; }
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    ///Returns \c true if \c a is \e surely negative
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    static bool negative(Value a) { return 0>a; }
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    ///Returns \c true if \c a is \e surely non-zero
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    static bool nonZero(Value a) { return a!=0; }
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    ///@}
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    ///Returns zero
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    static Value zero() {return 0;}
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  };
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  ///Unsigned integer specialization of Tolerance.
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  ///Unsigned integer specialization of Tolerance.
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  ///\sa Tolerance
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  template<>
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  class Tolerance<unsigned int>
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  {
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  public:
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    ///\e
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    typedef unsigned int Value;
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    ///\name Comparisons
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    ///See \ref lemon::Tolerance "Tolerance" for more details.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    static bool less(Value a,Value b) { return a<b;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    static bool different(Value a,Value b) { return a!=b; }
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    ///Returns \c true if \c a is \e surely positive
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    static bool positive(Value a) { return 0<a; }
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    ///Returns \c true if \c a is \e surely negative
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    static bool negative(Value) { return false; }
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    ///Returns \c true if \c a is \e surely non-zero
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    static bool nonZero(Value a) { return a!=0; }
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    ///@}
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    ///Returns zero
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    static Value zero() {return 0;}
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  };
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  ///Long integer specialization of Tolerance.
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  ///Long integer specialization of Tolerance.
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  ///\sa Tolerance
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  template<>
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  class Tolerance<long int>
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  {
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  public:
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    ///\e
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    typedef long int Value;
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    ///\name Comparisons
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    ///See \ref lemon::Tolerance "Tolerance" for more details.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    static bool less(Value a,Value b) { return a<b;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    static bool different(Value a,Value b) { return a!=b; }
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    ///Returns \c true if \c a is \e surely positive
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    static bool positive(Value a) { return 0<a; }
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    ///Returns \c true if \c a is \e surely negative
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    static bool negative(Value a) { return 0>a; }
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    ///Returns \c true if \c a is \e surely non-zero
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    static bool nonZero(Value a) { return a!=0;}
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    ///@}
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    ///Returns zero
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    static Value zero() {return 0;}
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  };
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  ///Unsigned long integer specialization of Tolerance.
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  ///Unsigned long integer specialization of Tolerance.
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  ///\sa Tolerance
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  template<>
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  class Tolerance<unsigned long int>
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  {
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  public:
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    ///\e
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    typedef unsigned long int Value;
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    ///\name Comparisons
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    ///See \ref lemon::Tolerance "Tolerance" for more details.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    static bool less(Value a,Value b) { return a<b;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    static bool different(Value a,Value b) { return a!=b; }
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    ///Returns \c true if \c a is \e surely positive
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    static bool positive(Value a) { return 0<a; }
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    ///Returns \c true if \c a is \e surely negative
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    static bool negative(Value) { return false; }
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    ///Returns \c true if \c a is \e surely non-zero
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    static bool nonZero(Value a) { return a!=0;}
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    ///@}
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    ///Returns zero
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    static Value zero() {return 0;}
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  };
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#if defined __GNUC__ && !defined __STRICT_ANSI__
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  ///Long long integer specialization of Tolerance.
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  ///Long long integer specialization of Tolerance.
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  ///\warning This class (more exactly, type <tt>long long</tt>)
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  ///is not ansi compatible.
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  ///\sa Tolerance
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  template<>
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  class Tolerance<long long int>
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  {
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  public:
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    ///\e
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    typedef long long int Value;
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    ///\name Comparisons
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    ///See \ref lemon::Tolerance "Tolerance" for more details.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    static bool less(Value a,Value b) { return a<b;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    static bool different(Value a,Value b) { return a!=b; }
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    ///Returns \c true if \c a is \e surely positive
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    static bool positive(Value a) { return 0<a; }
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    ///Returns \c true if \c a is \e surely negative
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    static bool negative(Value a) { return 0>a; }
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    ///Returns \c true if \c a is \e surely non-zero
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    static bool nonZero(Value a) { return a!=0;}
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    ///@}
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    ///Returns zero
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    static Value zero() {return 0;}
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  };
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  ///Unsigned long long integer specialization of Tolerance.
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  ///Unsigned long long integer specialization of Tolerance.
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  ///\warning This class (more exactly, type <tt>unsigned long long</tt>)
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  ///is not ansi compatible.
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  ///\sa Tolerance
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  template<>
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  class Tolerance<unsigned long long int>
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  {
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  public:
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    ///\e
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    typedef unsigned long long int Value;
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    ///\name Comparisons
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    ///See \ref lemon::Tolerance "Tolerance" for more details.
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    ///@{
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    ///Returns \c true if \c a is \e surely strictly less than \c b
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    static bool less(Value a,Value b) { return a<b;}
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    ///Returns \c true if \c a is \e surely different from \c b
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    static bool different(Value a,Value b) { return a!=b; }
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    ///Returns \c true if \c a is \e surely positive
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    static bool positive(Value a) { return 0<a; }
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    ///Returns \c true if \c a is \e surely negative
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    static bool negative(Value) { return false; }
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    ///Returns \c true if \c a is \e surely non-zero
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    static bool nonZero(Value a) { return a!=0;}
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    ///@}
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    ///Returns zero
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    static Value zero() {return 0;}
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  };
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#endif
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  /// @}
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} //namespace lemon
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#endif //LEMON_TOLERANCE_H