fuzzy_equal_to is a predicate to test two doubles for equality with a certain tolerance. A tolerance of 0.0 denotes that an exact match is requested. Note that the value of 0.0 cannot be compared fuzzily.

fuzzy_equal_to.h


//---------------------------------------------------------------------------

/*

fuzzy_equal_to, fuzzy equal_to predicate

Copyright (C) 2010 Richel Bilderbeek



This program is free software: you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation, either version 3 of the License, or

(at your option) any later version.



This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program. If not, see <http://www.gnu.org/licenses/>.

*/

//---------------------------------------------------------------------------

//From http://www.richelbilderbeek.nl/CppAbout.htm

//---------------------------------------------------------------------------

#ifndef FUZZY_EQUAL_TO_H

#define FUZZY_EQUAL_TO_H

//---------------------------------------------------------------------------

#ifdef _WIN32

//See http://www.richelbilderbeek.nl/CppCompileErrorSwprintfHasNotBeenDeclared.htm

#undef __STRICT_ANSI__

#endif

//---------------------------------------------------------------------------

#include <cassert>

#include <functional>

#include <string>

#include <vector>

//---------------------------------------------------------------------------

///fuzzy_equal_to is a predicate to test two doubles for equality

///with a certain tolerance. A tolerance of 0.0 denotes that

///an exact match is requested. Note that the value of 0.0 cannot

///be compared fuzzily.

struct fuzzy_equal_to

  : public std::binary_function<double,double,bool>

{

  fuzzy_equal_to(const double tolerance = 0.01)

    : m_tolerance(tolerance)

  {

    assert(tolerance >= 0.0);

  }

  bool operator()(const double lhs, const double rhs) const

  {

    return rhs > (1.0 - m_tolerance) * lhs

        && rhs < (1.0 + m_tolerance) * lhs;

  }

  const double m_tolerance;



  static const std::string GetVersion()

  {

    return "1.0";

  }

  static const std::vector<std::string> GetVersionHistory()

  {

    std::vector<std::string> v;

    v.push_back("2011-02-24: version 1.0: initial version");

    return v;

  }

};

//---------------------------------------------------------------------------

#endif // FUZZY_EQUAL_TO_H

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.

This page has been created by the tool CodeToHtml

(C++) Fuzzy_equal_to

fuzzy_equal_to.h